diff --git a/thys/Word_Lib/Aligned.thy b/thys/Word_Lib/Aligned.thy
--- a/thys/Word_Lib/Aligned.thy
+++ b/thys/Word_Lib/Aligned.thy
@@ -1,895 +1,912 @@
 (*
  * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
  *
  * SPDX-License-Identifier: BSD-2-Clause
  *)
 
 section "Word Alignment"
 
 theory Aligned
 imports
   Word_Lib
   HOL_Lemmas
   More_Divides
 begin
 
 lift_definition is_aligned :: \<open>'a::len word \<Rightarrow> nat \<Rightarrow> bool\<close>
-  is \<open>\<lambda>k n. take_bit (min LENGTH('a) n) k = 0\<close>
-  by (simp only: ac_simps flip: take_bit_take_bit)
+  is \<open>\<lambda>k n. 2 ^ n dvd take_bit LENGTH('a) k\<close>
+  by simp
+
+lemma is_aligned_iff_udvd:
+  \<open>is_aligned w n \<longleftrightarrow> 2 ^ n udvd w\<close>
+  by transfer (simp flip: take_bit_eq_0_iff)
+
+lemma is_aligned_iff_take_bit_eq_0:
+  \<open>is_aligned w n \<longleftrightarrow> take_bit n w = 0\<close>
+  by (simp add: is_aligned_iff_udvd take_bit_eq_0_iff exp_dvd_iff_exp_udvd)
 
 lemma is_aligned_iff_dvd_int:
   \<open>is_aligned ptr n \<longleftrightarrow> 2 ^ n dvd uint ptr\<close>
-  by transfer (simp add: take_bit_eq_mod dvd_eq_mod_eq_0 mod_exp_eq)
+  by transfer simp
 
 lemma is_aligned_iff_dvd_nat:
-  \<open>is_aligned ptr n \<longleftrightarrow> 2 ^ n dvd unat ptr\<close> (is \<open>?P \<longleftrightarrow> ?Q\<close>)
+  \<open>is_aligned ptr n \<longleftrightarrow> 2 ^ n dvd unat ptr\<close>
 proof -
   have \<open>unat ptr = nat \<bar>uint ptr\<bar>\<close>
     by transfer simp
   then have \<open>2 ^ n dvd unat ptr \<longleftrightarrow> 2 ^ n dvd uint ptr\<close>
     by (simp only: dvd_nat_abs_iff) simp
   then show ?thesis
     by (simp add: is_aligned_iff_dvd_int)
 qed
 
-lemma is_aligned_mask:
-  \<open>is_aligned w n \<longleftrightarrow> w && mask n = 0\<close>
-  by transfer (simp flip: take_bit_eq_mask)
+lemma is_aligned_0 [simp]:
+  \<open>is_aligned 0 n\<close>
+  by transfer simp
 
-lemma is_aligned_to_bl:
-  "is_aligned (w :: 'a :: len word) n = (True \<notin> set (drop (size w - n) (to_bl w)))"
-  apply (simp add: is_aligned_mask eq_zero_set_bl)
-  apply (clarsimp simp: in_set_conv_nth word_size)
-  apply (simp add: to_bl_nth word_size cong: conj_cong)
-  apply (simp add: diff_diff_less)
-  apply safe
-   apply (case_tac "n \<le> LENGTH('a)")
-    prefer 2
-    apply (rule_tac x=i in exI)
-    apply clarsimp
-   apply (subgoal_tac "\<exists>j < LENGTH('a). j < n \<and> LENGTH('a) - n + j = i")
-    apply (erule exE)
-    apply (rule_tac x=j in exI)
-    apply clarsimp
-   apply (thin_tac "w !! t" for t)
-   apply (rule_tac x="i + n - LENGTH('a)" in exI)
-   apply clarsimp
-   apply arith
-  apply (rule_tac x="LENGTH('a) - n + i" in exI)
-  apply clarsimp
-  apply arith
+lemma is_aligned_at_0 [simp]:
+  \<open>is_aligned w 0\<close>
+  by transfer simp
+
+lemma is_aligned_beyond_length:
+  \<open>is_aligned w n \<longleftrightarrow> w = 0\<close> if \<open>LENGTH('a) \<le> n\<close> for w :: \<open>'a::len word\<close>
+  using that
+  apply (simp add: is_aligned_iff_udvd)
+  apply transfer
+  apply auto
   done
 
-lemma unat_power_lower [simp]:
-  assumes nv: "n < LENGTH('a::len)"
-  shows "unat ((2::'a::len word) ^ n) = 2 ^ n"
-  using assms by transfer simp
-
-lemma power_overflow:
-  "n \<ge> LENGTH('a) \<Longrightarrow> 2 ^ n = (0 :: 'a::len word)"
-  by simp
-
 lemma is_alignedI [intro?]:
-  fixes x::"'a::len word"
-  assumes xv: "x = 2 ^ n * k"
-  shows   "is_aligned x n"
-proof cases
-  assume nv: "n < LENGTH('a)"
-  show ?thesis
-    unfolding is_aligned_iff_dvd_nat
-  proof (rule dvdI [where k = "unat k mod 2 ^ (LENGTH('a) - n)"])
-    from xv
-    have "unat x = (unat (2::word32) ^ n * unat k) mod 2 ^ LENGTH('a)"
-      using nv
-      by (subst (asm) word_unat.Rep_inject [symmetric], simp,
-          subst unat_word_ariths, simp)
+  \<open>is_aligned x n\<close> if \<open>x = 2 ^ n * k\<close> for x :: \<open>'a::len word\<close>
+proof (unfold is_aligned_iff_udvd)
+  from that show \<open>2 ^ n udvd x\<close>
+    using dvd_triv_left exp_dvd_iff_exp_udvd by blast
+qed
 
-    also have "\<dots> =  2 ^ n * (unat k mod 2 ^ (LENGTH('a) - n))" using nv
-      by (simp add: mult_mod_right power_add [symmetric] add_diff_inverse)
-
-    finally show "unat x = 2 ^ n * (unat k mod 2 ^ (LENGTH('a) - n))" .
+lemma is_alignedE [elim?]:
+  fixes w :: \<open>'a::len word\<close>
+  assumes \<open>is_aligned w n\<close>
+  obtains q where \<open>w = 2 ^ n * word_of_nat q\<close> \<open>q < 2 ^ (LENGTH('a) - n)\<close>
+proof (cases \<open>n < LENGTH('a)\<close>)
+  case False
+  with assms have \<open>w = 0\<close>
+    by (simp add: is_aligned_beyond_length)
+  with that [of 0] show thesis
+    by simp
+next
+  case True
+  moreover define m where \<open>m = LENGTH('a) - n\<close>
+  ultimately have l: \<open>LENGTH('a) = n + m\<close> and \<open>m \<noteq> 0\<close>
+    by simp_all
+  from \<open>n < LENGTH('a)\<close> have *: \<open>unat (2 ^ n :: 'a word) = 2 ^ n\<close>
+    by transfer simp
+  from assms have \<open>2 ^ n udvd w\<close>
+    by (simp add: is_aligned_iff_udvd)
+  then obtain v :: \<open>'a word\<close>
+    where \<open>unat w = unat (2 ^ n :: 'a word) * unat v\<close> ..
+  moreover define q where \<open>q = unat v\<close>
+  ultimately have unat_w: \<open>unat w = 2 ^ n * q\<close>
+    by (simp add: *)
+  then have \<open>word_of_nat (unat w) = (word_of_nat (2 ^ n * q) :: 'a word)\<close>
+    by simp
+  then have w: \<open>w = 2 ^ n * word_of_nat q\<close>
+    by simp
+  moreover have \<open>q < 2 ^ (LENGTH('a) - n)\<close>
+  proof (rule ccontr)
+    assume \<open>\<not> q < 2 ^ (LENGTH('a) - n)\<close>
+    then have \<open>2 ^ (LENGTH('a) - n) \<le> q\<close>
+      by simp
+    then have \<open>2 ^ LENGTH('a) \<le> 2 ^ n * q\<close>
+      by (simp add: l power_add)
+    with unat_w [symmetric] show False
+      by (simp add: le_def)
   qed
-next
-  assume "\<not> n < LENGTH('a)"
-  with xv
-  show ?thesis
-    by (simp add: not_less power_overflow is_aligned_iff_dvd_nat)
+  ultimately show thesis
+    using that by blast
 qed
 
+lemma is_aligned_mask:
+  \<open>is_aligned w n \<longleftrightarrow> w && mask n = 0\<close>
+  by (simp add: is_aligned_iff_take_bit_eq_0 take_bit_eq_mask)
+
 lemma is_aligned_weaken:
   "\<lbrakk> is_aligned w x; x \<ge> y \<rbrakk> \<Longrightarrow> is_aligned w y"
   unfolding is_aligned_iff_dvd_nat
   by (erule dvd_trans [rotated]) (simp add: le_imp_power_dvd)
 
 lemma nat_power_less_diff:
   assumes lt: "(2::nat) ^ n * q < 2 ^ m"
   shows "q < 2 ^ (m - n)"
   using lt
 proof (induct n arbitrary: m)
   case 0
   then show ?case by simp
 next
   case (Suc n)
 
   have ih: "\<And>m. 2 ^ n * q < 2 ^ m \<Longrightarrow> q < 2 ^ (m - n)"
     and prem: "2 ^ Suc n * q < 2 ^ m" by fact+
 
   show ?case
   proof (cases m)
     case 0
     then show ?thesis using Suc by simp
   next
     case (Suc m')
     then show ?thesis using prem
       by (simp add: ac_simps ih)
   qed
 qed
 
 lemma is_alignedE_pre:
   fixes w::"'a::len word"
   assumes aligned: "is_aligned w n"
   shows        rl: "\<exists>q. w = 2 ^ n * (of_nat q) \<and> q < 2 ^ (LENGTH('a) - n)"
-proof -
-  from aligned obtain q where wv: "unat w = 2 ^ n * q"
-    unfolding is_aligned_iff_dvd_nat ..
-
-  show ?thesis
-  proof (rule exI, intro conjI)
-    show "q < 2 ^ (LENGTH('a) - n)"
-    proof (rule nat_power_less_diff)
-      have "unat w < 2 ^ size w" unfolding word_size ..
-      then have "unat w < 2 ^ LENGTH('a)" by simp
-      with wv show "2 ^ n * q < 2 ^ LENGTH('a)" by simp
-    qed
+  using aligned is_alignedE by blast
 
-    have r: "of_nat (2 ^ n) = (2::word32) ^ n"
-      by (induct n) simp+
+lemma is_aligned_to_bl:
+  "is_aligned (w :: 'a :: len word) n = (True \<notin> set (drop (size w - n) (to_bl w)))"
+  apply (simp add: is_aligned_mask eq_zero_set_bl)
+  apply (clarsimp simp: in_set_conv_nth word_size)
+  apply (simp add: to_bl_nth word_size cong: conj_cong)
+  apply (simp add: diff_diff_less)
+  apply safe
+   apply (case_tac "n \<le> LENGTH('a)")
+    prefer 2
+    apply (rule_tac x=i in exI)
+    apply clarsimp
+   apply (subgoal_tac "\<exists>j < LENGTH('a). j < n \<and> LENGTH('a) - n + j = i")
+    apply (erule exE)
+    apply (rule_tac x=j in exI)
+    apply clarsimp
+   apply (thin_tac "w !! t" for t)
+   apply (rule_tac x="i + n - LENGTH('a)" in exI)
+   apply clarsimp
+   apply arith
+  apply (rule_tac x="LENGTH('a) - n + i" in exI)
+  apply clarsimp
+  apply arith
+  done
 
-    from wv have "of_nat (unat w) = of_nat (2 ^ n * q)" by simp
-    then have "w = of_nat (2 ^ n * q)" by (subst word_unat.Rep_inverse [symmetric])
-    then show "w = 2 ^ n * (of_nat q)" by (simp add: r)
-  qed
-qed
+lemma unat_power_lower [simp]:
+  assumes nv: "n < LENGTH('a::len)"
+  shows "unat ((2::'a::len word) ^ n) = 2 ^ n"
+  using assms by transfer simp
 
-lemma is_alignedE:
-  "\<lbrakk>is_aligned (w::'a::len word) n;
-    \<And>q. \<lbrakk>w = 2 ^ n * (of_nat q); q < 2 ^ (LENGTH('a) - n)\<rbrakk> \<Longrightarrow> R\<rbrakk> \<Longrightarrow> R"
-  by (auto dest: is_alignedE_pre)
+lemma power_overflow:
+  "n \<ge> LENGTH('a) \<Longrightarrow> 2 ^ n = (0 :: 'a::len word)"
+  by simp
 
 lemma is_aligned_replicate:
   fixes w::"'a::len word"
   assumes aligned: "is_aligned w n"
   and          nv: "n \<le> LENGTH('a)"
   shows   "to_bl w = (take (LENGTH('a) - n) (to_bl w)) @ replicate n False"
 proof -
   from nv have rl: "\<And>q. q < 2 ^ (LENGTH('a) - n) \<Longrightarrow>
       to_bl (2 ^ n * (of_nat q :: 'a word)) =
       drop n (to_bl (of_nat q :: 'a word)) @ replicate n False"
     by (metis bl_shiftl le_antisym min_def shiftl_t2n wsst_TYs(3))
   show ?thesis using aligned
     by (auto simp: rl elim: is_alignedE)
 qed
 
 lemma is_aligned_drop:
   fixes w::"'a::len word"
   assumes "is_aligned w n" "n \<le> LENGTH('a)"
   shows "drop (LENGTH('a) - n) (to_bl w) = replicate n False"
 proof -
   have "to_bl w = take (LENGTH('a) - n) (to_bl w) @ replicate n False"
     by (rule is_aligned_replicate) fact+
   then have "drop (LENGTH('a) - n) (to_bl w) = drop (LENGTH('a) - n) \<dots>" by simp
   also have "\<dots> = replicate n False" by simp
   finally show ?thesis .
 qed
 
 lemma less_is_drop_replicate:
   fixes x::"'a::len word"
   assumes lt: "x < 2 ^ n"
   shows   "to_bl x = replicate (LENGTH('a) - n) False @ drop (LENGTH('a) - n) (to_bl x)"
   by (metis assms bl_and_mask' less_mask_eq)
 
 lemma is_aligned_add_conv:
   fixes off::"'a::len word"
   assumes aligned: "is_aligned w n"
   and        offv: "off < 2 ^ n"
   shows    "to_bl (w + off) =
    (take (LENGTH('a) - n) (to_bl w)) @ (drop (LENGTH('a) - n) (to_bl off))"
 proof cases
   assume nv: "n \<le> LENGTH('a)"
   show ?thesis
   proof (subst aligned_bl_add_size, simp_all only: word_size)
     show "drop (LENGTH('a) - n) (to_bl w) = replicate n False"
       by (subst is_aligned_replicate [OF aligned nv]) (simp add: word_size)
 
     from offv show "take (LENGTH('a) - n) (to_bl off) =
                     replicate (LENGTH('a) - n) False"
       by (subst less_is_drop_replicate, assumption) simp
   qed fact
 next
   assume "\<not> n \<le> LENGTH('a)"
   with offv show ?thesis by (simp add: power_overflow)
 qed
 
 lemma aligned_add_aligned:
   fixes x::"'a::len word"
   assumes aligned1: "is_aligned x n"
   and     aligned2: "is_aligned y m"
   and           lt: "m \<le> n"
   shows   "is_aligned (x + y) m"
 proof cases
   assume nlt: "n < LENGTH('a)"
   show ?thesis
     unfolding is_aligned_iff_dvd_nat dvd_def
   proof -
     from aligned2 obtain q2 where yv: "y = 2 ^ m * of_nat q2"
       and q2v: "q2 < 2 ^ (LENGTH('a) - m)"
       by (auto elim: is_alignedE)
 
     from lt obtain k where kv: "m + k = n" by (auto simp: le_iff_add)
     with aligned1 obtain q1 where xv: "x = 2 ^ (m + k) * of_nat q1"
       and q1v: "q1 < 2 ^ (LENGTH('a) - (m + k))"
       by (auto elim: is_alignedE)
 
     have l1: "2 ^ (m + k) * q1 < 2 ^ LENGTH('a)"
       by (rule nat_less_power_trans [OF q1v])
          (subst kv, rule order_less_imp_le [OF nlt])
 
     have l2: "2 ^ m * q2 < 2 ^ LENGTH('a)"
       by (rule nat_less_power_trans [OF q2v],
           rule order_less_imp_le [OF order_le_less_trans])
          fact+
 
     have "x = of_nat (2 ^ (m + k) *  q1)" using xv
       by simp
 
     moreover have "y = of_nat (2 ^ m * q2)" using yv
       by simp
 
     ultimately have upls: "unat x + unat y = 2 ^ m * (2 ^ k * q1 + q2)"
     proof -
       have f1: "unat x = 2 ^ (m + k) * q1"
         by (metis (no_types) \<open>x = of_nat (2 ^ (m + k) * q1)\<close> l1 nat_mod_lem word_unat.inverse_norm
                              zero_less_numeral zero_less_power)
       have "unat y = 2 ^ m * q2"
         by (metis (no_types) \<open>y = of_nat (2 ^ m * q2)\<close> l2 nat_mod_lem word_unat.inverse_norm
                              zero_less_numeral zero_less_power)
       then show ?thesis
         using f1 by (simp add: power_add semiring_normalization_rules(34))
     qed
 
     (* (2 ^ k * q1 + q2) *)
     show "\<exists>d. unat (x + y) = 2 ^ m * d"
     proof (cases "unat x + unat y < 2 ^ LENGTH('a)")
       case True
 
       have "unat (x + y) = unat x + unat y"
         by (subst unat_plus_if', rule if_P) fact
 
       also have "\<dots> = 2 ^ m * (2 ^ k * q1 + q2)" by (rule upls)
       finally show ?thesis ..
     next
       case False
       then have "unat (x + y) = (unat x + unat y) mod 2 ^ LENGTH('a)"
         by (subst unat_word_ariths(1)) simp
 
       also have "\<dots> = (2 ^ m * (2 ^ k * q1 + q2)) mod 2 ^ LENGTH('a)"
         by (subst upls, rule refl)
 
       also
       have "\<dots> = 2 ^ m * ((2 ^ k * q1 +  q2) mod 2 ^ (LENGTH('a) - m))"
       proof -
         have "m \<le> len_of (TYPE('a))"
           by (meson le_trans less_imp_le_nat lt nlt)
         then show ?thesis
           by (metis mult_mod_right ordered_cancel_comm_monoid_diff_class.add_diff_inverse power_add)
       qed
 
       finally show ?thesis ..
     qed
   qed
 next
   assume "\<not> n < LENGTH('a)"
   with assms
   show ?thesis
     by (simp add: is_aligned_mask not_less take_bit_eq_mod power_overflow word_arith_nat_defs(7) flip: take_bit_eq_mask)
 qed
 
 corollary aligned_sub_aligned:
   "\<lbrakk>is_aligned (x::'a::len word) n; is_aligned y m; m \<le> n\<rbrakk>
    \<Longrightarrow> is_aligned (x - y) m"
   apply (simp del: add_uminus_conv_diff add:diff_conv_add_uminus)
   apply (erule aligned_add_aligned, simp_all)
   apply (erule is_alignedE)
   apply (rule_tac k="- of_nat q" in is_alignedI)
   apply simp
   done
 
 lemma is_aligned_shift:
   fixes k::"'a::len word"
   shows "is_aligned (k << m) m"
 proof cases
   assume mv: "m < LENGTH('a)"
   from mv obtain q where mq: "m + q = LENGTH('a)" and "0 < q"
     by (auto dest: less_imp_add_positive)
 
   have "(2::nat) ^ m dvd unat (k << m)"
   proof
     have kv: "(unat k div 2 ^ q) * 2 ^ q + unat k mod 2 ^ q = unat k"
       by (rule div_mult_mod_eq)
 
     have "unat (k << m) = unat (2 ^ m * k)" by (simp add: shiftl_t2n)
     also have "\<dots> = (2 ^ m * unat k) mod (2 ^ LENGTH('a))" using mv
       by (subst unat_word_ariths(2))+ simp
     also have "\<dots> = 2 ^ m * (unat k mod 2 ^ q)"
       by (subst mq [symmetric], subst power_add, subst mod_mult2_eq) simp
     finally show "unat (k << m) = 2 ^ m * (unat k mod 2 ^ q)" .
   qed
 
   then show ?thesis by (unfold is_aligned_iff_dvd_nat)
 next
   assume "\<not> m < LENGTH('a)"
   then show ?thesis
     by (simp add: not_less power_overflow is_aligned_mask shiftl_zero_size word_size)
 qed
 
 lemma word_mod_by_0: "k mod (0::'a::len word) = k"
   by (simp add: word_arith_nat_mod)
 
 lemma aligned_mod_eq_0:
   fixes p::"'a::len word"
   assumes al: "is_aligned p sz"
   shows   "p mod 2 ^ sz = 0"
 proof cases
   assume szv: "sz < LENGTH('a)"
   with al
   show ?thesis
     unfolding is_aligned_iff_dvd_nat
     by (simp add: and_mask_dvd_nat p2_gt_0 word_mod_2p_is_mask)
 next
   assume "\<not> sz < LENGTH('a)"
   with al show ?thesis
     by (simp add: is_aligned_mask flip: take_bit_eq_mask take_bit_eq_mod)
 qed
 
 lemma is_aligned_triv: "is_aligned (2 ^ n ::'a::len word) n"
   by (rule is_alignedI [where k = 1], simp)
 
 lemma is_aligned_mult_triv1: "is_aligned (2 ^ n * x  ::'a::len word) n"
   by (rule is_alignedI [OF refl])
 
 lemma is_aligned_mult_triv2: "is_aligned (x * 2 ^ n ::'a::len word) n"
   by (subst mult.commute, simp add: is_aligned_mult_triv1)
 
 lemma word_power_less_0_is_0:
   fixes x :: "'a::len word"
   shows "x < a ^ 0 \<Longrightarrow> x = 0" by simp
 
 lemma nat_add_offset_less:
   fixes x :: nat
   assumes yv: "y < 2 ^ n"
   and     xv: "x < 2 ^ m"
   and     mn: "sz = m + n"
   shows   "x * 2 ^ n + y < 2 ^ sz"
 proof (subst mn)
   from yv obtain qy where "y + qy = 2 ^ n" and "0 < qy"
     by (auto dest: less_imp_add_positive)
 
   have "x * 2 ^ n + y < x * 2 ^ n + 2 ^ n" by simp fact+
   also have "\<dots> = (x + 1) * 2 ^ n" by simp
   also have "\<dots> \<le> 2 ^ (m + n)" using xv
     by (subst power_add) (rule mult_le_mono1, simp)
   finally show "x * 2 ^ n + y < 2 ^ (m + n)" .
 qed
 
 lemma is_aligned_no_wrap:
   fixes off :: "'a::len word"
   fixes ptr :: "'a::len word"
   assumes al: "is_aligned ptr sz"
   and    off: "off < 2 ^ sz"
   shows  "unat ptr + unat off < 2 ^ LENGTH('a)"
 proof -
   have szv: "sz < LENGTH('a)"
   using off p2_gt_0 word_neq_0_conv by fastforce
 
   from al obtain q where ptrq: "ptr = 2 ^ sz * of_nat q" and
     qv: "q < 2 ^ (LENGTH('a) - sz)" by (auto elim: is_alignedE)
 
   show ?thesis
   proof (cases "sz = 0")
     case True
     then show ?thesis using off ptrq qv
       by (simp add: take_bit_nat_less_exp)
   next
     case False
     then have sne: "0 < sz" ..
 
     show ?thesis
     proof -
       have uq: "unat (of_nat q ::'a::len word) = q"
         apply (subst unat_of_nat)
         apply (rule mod_less)
         apply (rule order_less_trans [OF qv])
         apply (rule power_strict_increasing [OF diff_less [OF sne]])
          apply (simp_all)
         done
 
       have uptr: "unat ptr = 2 ^ sz * q"
         apply (subst ptrq)
         apply (subst iffD1 [OF unat_mult_lem])
          apply (subst unat_power_lower [OF szv])
          apply (subst uq)
          apply (rule nat_less_power_trans [OF qv order_less_imp_le [OF szv]])
         apply (subst uq)
         apply (subst unat_power_lower [OF szv])
         apply simp
         done
 
       show "unat ptr + unat off < 2 ^ LENGTH('a)" using szv
         apply (subst uptr)
         apply (subst mult.commute, rule nat_add_offset_less [OF _ qv])
         apply (rule order_less_le_trans [OF unat_mono [OF off] order_eq_refl])
          apply simp_all
         done
     qed
   qed
 qed
 
 lemma is_aligned_no_wrap':
   fixes ptr :: "'a::len word"
   assumes al: "is_aligned ptr sz"
   and    off: "off < 2 ^ sz"
   shows  "ptr \<le> ptr + off"
   by (subst no_plus_overflow_unat_size, subst word_size, rule is_aligned_no_wrap) fact+
 
 lemma is_aligned_no_overflow':
   fixes p :: "'a::len word"
   assumes al: "is_aligned p n"
   shows "p \<le> p + (2 ^ n - 1)"
 proof cases
   assume "n<LENGTH('a)"
   with al
   have "2^n - (1::'a::len word) < 2^n"
     by (simp add: word_less_nat_alt unat_sub_if_size)
   with al
   show ?thesis by (rule is_aligned_no_wrap')
 next
   assume "\<not> n<LENGTH('a)"
   with al
   show ?thesis
   by (simp add: not_less power_overflow is_aligned_mask mask_2pm1)
 qed
 
 lemma is_aligned_no_overflow:
   "is_aligned ptr sz \<Longrightarrow> ptr \<le> ptr + 2^sz - 1"
   by (drule is_aligned_no_overflow') (simp add: field_simps)
 
 lemma replicate_not_True:
   "\<And>n. xs = replicate n False \<Longrightarrow> True \<notin> set xs"
   by (induct xs) auto
 
 lemma is_aligned_replicateI:
   "to_bl p = addr @ replicate n False \<Longrightarrow> is_aligned (p::'a::len word) n"
   apply (simp add: is_aligned_to_bl word_size)
   apply (subgoal_tac "length addr = LENGTH('a) - n")
    apply (simp add: replicate_not_True)
   apply (drule arg_cong [where f=length])
   apply simp
   done
 
 lemma to_bl_2p:
   "n < LENGTH('a) \<Longrightarrow>
    to_bl ((2::'a::len word) ^ n) =
    replicate (LENGTH('a) - Suc n) False @ True # replicate n False"
   apply (subst shiftl_1 [symmetric])
   apply (subst bl_shiftl)
   apply (simp add: to_bl_1 min_def word_size)
   done
 
 lemma map_zip_replicate_False_xor:
   "n = length xs \<Longrightarrow> map (\<lambda>(x, y). x = (\<not> y)) (zip xs (replicate n False)) = xs"
   by (induct xs arbitrary: n, auto)
 
 lemma drop_minus_lem:
   "\<lbrakk> n \<le> length xs; 0 < n; n' = length xs \<rbrakk> \<Longrightarrow> drop (n' - n) xs = rev xs ! (n - 1)  # drop (Suc (n' - n)) xs"
 proof (induct xs arbitrary: n n')
   case Nil then show ?case by simp
 next
   case (Cons y ys)
   from Cons.prems
   show ?case
     apply simp
     apply (cases "n = Suc (length ys)")
      apply (simp add: nth_append)
     apply (simp add: Suc_diff_le Cons.hyps nth_append)
     apply clarsimp
     apply arith
     done
 qed
 
 lemma drop_minus:
   "\<lbrakk> n < length xs; n' = length xs \<rbrakk> \<Longrightarrow> drop (n' - Suc n) xs = rev xs ! n  # drop (n' - n) xs"
   apply (subst drop_minus_lem)
      apply simp
     apply simp
    apply simp
   apply simp
   apply (cases "length xs", simp)
   apply (simp add: Suc_diff_le)
   done
 
 lemma xor_2p_to_bl:
   fixes x::"'a::len word"
   shows "to_bl (x xor 2^n) =
   (if n < LENGTH('a)
    then take (LENGTH('a)-Suc n) (to_bl x) @ (\<not>rev (to_bl x)!n) # drop (LENGTH('a)-n) (to_bl x)
    else to_bl x)"
 proof -
   have x: "to_bl x = take (LENGTH('a)-Suc n) (to_bl x) @ drop (LENGTH('a)-Suc n) (to_bl x)"
     by simp
 
   show ?thesis
   apply simp
   apply (rule conjI)
    apply (clarsimp simp: word_size)
    apply (simp add: bl_word_xor to_bl_2p)
    apply (subst x)
    apply (subst zip_append)
     apply simp
    apply (simp add: map_zip_replicate_False_xor drop_minus)
   apply (auto simp add: word_size nth_w2p intro!: word_eqI)
   done
 qed
 
 lemma aligned_add_xor:
   assumes al: "is_aligned (x::'a::len word) n'" and le: "n < n'"
   shows "(x + 2^n) xor 2^n = x"
 proof cases
   assume "n' < LENGTH('a)"
   with assms show ?thesis
   apply -
   apply (rule word_bl.Rep_eqD)
   apply (subst xor_2p_to_bl)
   apply simp
   apply (subst is_aligned_add_conv, simp, simp add: word_less_nat_alt)+
   apply (simp add: to_bl_2p nth_append)
   apply (cases "n' = Suc n")
    apply simp
    apply (subst is_aligned_replicate [where n="Suc n", simplified, symmetric]; simp)
   apply (subgoal_tac "\<not> LENGTH('a) - Suc n \<le> LENGTH('a) - n'")
    prefer 2
    apply arith
   apply (subst replicate_Suc [symmetric])
   apply (subst replicate_add [symmetric])
   apply (simp add: is_aligned_replicate [simplified, symmetric])
   done
 next
   assume "\<not> n' < LENGTH('a)"
   show ?thesis
     using al apply (rule is_alignedE)
     using \<open>\<not> n' < LENGTH('a)\<close> by auto
 qed
 
-lemma is_aligned_0 [simp]:
-  "is_aligned p 0"
-  by (simp add: is_aligned_iff_dvd_nat)
-
 lemma is_aligned_replicateD:
   "\<lbrakk> is_aligned (w::'a::len word) n; n \<le> LENGTH('a) \<rbrakk>
      \<Longrightarrow> \<exists>xs. to_bl w = xs @ replicate n False
                \<and> length xs = size w - n"
   apply (subst is_aligned_replicate, assumption+)
   apply (rule exI, rule conjI, rule refl)
   apply (simp add: word_size)
   done
 
 lemma is_aligned_add_mult_multI:
   fixes p :: "'a::len word"
   shows "\<lbrakk>is_aligned p m; n \<le> m; n' = n\<rbrakk> \<Longrightarrow> is_aligned (p + x * 2 ^ n * z) n'"
   apply (erule aligned_add_aligned)
   apply (auto intro: is_alignedI [where k="x*z"])
   done
 
 lemma is_aligned_add_multI:
   fixes p :: "'a::len word"
   shows "\<lbrakk>is_aligned p m; n \<le> m; n' = n\<rbrakk> \<Longrightarrow> is_aligned (p + x * 2 ^ n) n'"
   apply (erule aligned_add_aligned)
   apply (auto intro: is_alignedI [where k="x"])
   done
 
 lemma unat_of_nat_len:
   "x < 2 ^ LENGTH('a) \<Longrightarrow> unat (of_nat x :: 'a::len word) = x"
   by (simp add: take_bit_nat_eq_self_iff)
 
 lemma is_aligned_no_wrap''':
   fixes ptr :: "'a::len word"
   shows"\<lbrakk> is_aligned ptr sz; sz < LENGTH('a); off < 2 ^ sz \<rbrakk>
          \<Longrightarrow> unat ptr + off < 2 ^ LENGTH('a)"
   apply (drule is_aligned_no_wrap[where off="of_nat off"])
    apply (simp add: word_less_nat_alt)
    apply (erule order_le_less_trans[rotated])
   apply (simp add: take_bit_eq_mod)
   apply (subst(asm) unat_of_nat_len)
    apply (erule order_less_trans)
    apply (erule power_strict_increasing)
    apply simp
   apply assumption
   done
 
 lemma is_aligned_get_word_bits:
   fixes p :: "'a::len word"
   shows "\<lbrakk> is_aligned p n; \<lbrakk> is_aligned p n; n < LENGTH('a) \<rbrakk> \<Longrightarrow> P;
            \<lbrakk> p = 0; n \<ge> LENGTH('a) \<rbrakk> \<Longrightarrow> P \<rbrakk> \<Longrightarrow> P"
   apply (cases "n < LENGTH('a)")
    apply simp
   apply simp
   apply (erule meta_mp)
   apply (simp add: is_aligned_mask power_add power_overflow not_less
     flip: take_bit_eq_mask)
   apply (metis take_bit_length_eq take_bit_of_0 take_bit_tightened)
   done
 
 lemma aligned_small_is_0:
   "\<lbrakk> is_aligned x n; x < 2 ^ n \<rbrakk> \<Longrightarrow> x = 0"
   apply (erule is_aligned_get_word_bits)
    apply (frule is_aligned_add_conv [rotated, where w=0])
     apply (simp add: is_aligned_iff_dvd_nat)
    apply simp
    apply (drule is_aligned_replicateD)
     apply simp
    apply (clarsimp simp: word_size)
    apply (subst (asm) replicate_add [symmetric])
    apply (drule arg_cong[where f="of_bl :: bool list \<Rightarrow> 'a::len word"])
    apply simp
   apply (simp only: replicate.simps[symmetric, where x=False]
                     drop_replicate)
   done
 
 corollary is_aligned_less_sz:
   "\<lbrakk>is_aligned a sz; a \<noteq> 0\<rbrakk> \<Longrightarrow> \<not> a < 2 ^ sz"
   by (rule notI, drule(1) aligned_small_is_0, erule(1) notE)
 
 lemma aligned_at_least_t2n_diff:
   "\<lbrakk>is_aligned x n; is_aligned y n; x < y\<rbrakk> \<Longrightarrow> x \<le> y - 2 ^ n"
   apply (erule is_aligned_get_word_bits[where p=y])
    apply (rule ccontr)
    apply (clarsimp simp: linorder_not_le)
    apply (subgoal_tac "y - x = 0")
     apply clarsimp
    apply (rule aligned_small_is_0)
     apply (erule(1) aligned_sub_aligned)
     apply simp
    apply unat_arith
   apply simp
   done
 
 lemma word_sub_1_le:
   "x \<noteq> 0 \<Longrightarrow> x - 1 \<le> (x :: ('a :: len) word)"
   apply (subst no_ulen_sub)
   apply simp
   apply (cases "uint x = 0")
    apply (simp add: uint_0_iff)
   apply (insert uint_ge_0[where x=x])
   apply arith
   done
 
 lemma is_aligned_no_overflow'':
   "\<lbrakk>is_aligned x n; x + 2 ^ n \<noteq> 0\<rbrakk> \<Longrightarrow> x \<le> x + 2 ^ n"
   apply (frule is_aligned_no_overflow')
   apply (erule order_trans)
   apply (simp add: field_simps)
   apply (erule word_sub_1_le)
   done
 
 lemma is_aligned_nth:
   "is_aligned p m = (\<forall>n < m. \<not>p !! n)"
   apply (clarsimp simp: is_aligned_mask bang_eq word_size)
   apply (rule iffI)
    apply clarsimp
    apply (case_tac "n < size p")
     apply (simp add: word_size)
    apply (drule test_bit_size)
    apply simp
   apply clarsimp
   done
 
 lemma range_inter:
   "({a..b} \<inter> {c..d} = {}) = (\<forall>x. \<not>(a \<le> x \<and> x \<le> b \<and> c \<le> x \<and> x \<le> d))"
   by auto
 
 lemma aligned_inter_non_empty:
   "\<lbrakk> {p..p + (2 ^ n - 1)} \<inter> {p..p + 2 ^ m - 1} = {};
      is_aligned p n; is_aligned p m\<rbrakk> \<Longrightarrow> False"
   apply (clarsimp simp only: range_inter)
   apply (erule_tac x=p in allE)
   apply simp
   apply (erule impE)
    apply (erule is_aligned_no_overflow')
   apply (erule notE)
   apply (erule is_aligned_no_overflow)
   done
 
 lemma not_aligned_mod_nz:
   assumes al: "\<not> is_aligned a n"
   shows "a mod 2 ^ n \<noteq> 0"
   apply (rule ccontr)
   using al apply (rule notE)
   apply simp
   apply (rule is_alignedI [of _ _ \<open>a div 2 ^ n\<close>])
   apply (metis add.right_neutral mult.commute word_mod_div_equality)
   done
 
 lemma nat_add_offset_le:
   fixes x :: nat
   assumes yv: "y \<le> 2 ^ n"
   and     xv: "x < 2 ^ m"
   and     mn: "sz = m + n"
   shows   "x * 2 ^ n + y \<le> 2 ^ sz"
 proof (subst mn)
   from yv obtain qy where "y + qy = 2 ^ n"
     by (auto simp: le_iff_add)
 
   have "x * 2 ^ n + y \<le> x * 2 ^ n + 2 ^ n"
     using yv xv by simp
   also have "\<dots> = (x + 1) * 2 ^ n" by simp
   also have "\<dots> \<le> 2 ^ (m + n)" using xv
     by (subst power_add) (rule mult_le_mono1, simp)
   finally show "x * 2 ^ n + y \<le> 2 ^ (m + n)" .
 qed
 
 lemma is_aligned_no_wrap_le:
   fixes ptr::"'a::len word"
   assumes al: "is_aligned ptr sz"
   and    szv: "sz < LENGTH('a)"
   and    off: "off \<le> 2 ^ sz"
   shows  "unat ptr + off \<le> 2 ^ LENGTH('a)"
 proof -
   from al obtain q where ptrq: "ptr = 2 ^ sz * of_nat q" and
     qv: "q < 2 ^ (LENGTH('a) - sz)" by (auto elim: is_alignedE)
 
   show ?thesis
   proof (cases "sz = 0")
     case True
     then show ?thesis using off ptrq qv
       by (auto simp add: le_Suc_eq Suc_le_eq) (simp add: le_less)
   next
     case False
     then have sne: "0 < sz" ..
 
     show ?thesis
     proof -
       have uq: "unat (of_nat q :: 'a word) = q"
         apply (subst unat_of_nat)
         apply (rule mod_less)
         apply (rule order_less_trans [OF qv])
         apply (rule power_strict_increasing [OF diff_less [OF sne]])
         apply simp_all
         done
 
       have uptr: "unat ptr = 2 ^ sz * q"
         apply (subst ptrq)
         apply (subst iffD1 [OF unat_mult_lem])
         apply (subst unat_power_lower [OF szv])
         apply (subst uq)
         apply (rule nat_less_power_trans [OF qv order_less_imp_le [OF szv]])
         apply (subst uq)
         apply (subst unat_power_lower [OF szv])
         apply simp
         done
 
       show "unat ptr + off \<le> 2 ^ LENGTH('a)" using szv
         apply (subst uptr)
         apply (subst mult.commute, rule nat_add_offset_le [OF off qv])
         apply simp
         done
     qed
   qed
 qed
 
 lemma is_aligned_neg_mask:
   "m \<le> n \<Longrightarrow> is_aligned (x && ~~ (mask n)) m"
   by (metis and_not_mask is_aligned_shift is_aligned_weaken)
 
 lemma unat_minus:
   "unat (- (x :: 'a :: len word)) = (if x = 0 then 0 else 2 ^ size x - unat x)"
   using unat_sub_if_size[where x="2 ^ size x" and y=x]
   by (simp add: unat_eq_0 word_size)
 
 lemma is_aligned_minus:
-  "is_aligned p n \<Longrightarrow> is_aligned (- p) n"
-  apply (clarsimp simp: is_aligned_iff_dvd_nat unat_minus word_size word_neq_0_conv)
-  apply (rule dvd_diff_nat, simp_all)
-  apply (rule le_imp_power_dvd)
-  apply (fold is_aligned_iff_dvd_nat)
-  apply (erule_tac Q="0<p" in contrapos_pp)
+  \<open>is_aligned (- p) n\<close> if \<open>is_aligned p n\<close> for p :: \<open>'a::len word\<close>
+  using that
+  apply (cases \<open>n < LENGTH('a)\<close>)
+  apply (simp_all add: not_less is_aligned_beyond_length)
   apply transfer
+  apply (simp flip: take_bit_eq_0_iff)
+  apply (subst take_bit_minus [symmetric])
   apply simp
   done
 
 lemma add_mask_lower_bits:
   "\<lbrakk>is_aligned (x :: 'a :: len word) n;
     \<forall>n' \<ge> n. n' < LENGTH('a) \<longrightarrow> \<not> p !! n'\<rbrakk> \<Longrightarrow> x + p && ~~ (mask n) = x"
   apply (subst word_plus_and_or_coroll)
    apply (rule word_eqI)
    apply (clarsimp simp: word_size is_aligned_nth)
    apply (erule_tac x=na in allE)+
    apply simp
   apply (rule word_eqI)
   apply (clarsimp simp: word_size is_aligned_nth word_ops_nth_size le_def)
   apply blast
   done
 
 lemma is_aligned_andI1:
   "is_aligned x n \<Longrightarrow> is_aligned (x && y) n"
   by (simp add: is_aligned_nth)
 
 lemma is_aligned_andI2:
   "is_aligned y n \<Longrightarrow> is_aligned (x && y) n"
   by (simp add: is_aligned_nth)
 
 lemma is_aligned_shiftl:
   "is_aligned w (n - m) \<Longrightarrow> is_aligned (w << m) n"
   by (simp add: is_aligned_nth nth_shiftl)
 
 lemma is_aligned_shiftr:
   "is_aligned w (n + m) \<Longrightarrow> is_aligned (w >> m) n"
   by (simp add: is_aligned_nth nth_shiftr)
 
 lemma is_aligned_shiftl_self:
   "is_aligned (p << n) n"
   by (rule is_aligned_shift)
 
 lemma is_aligned_neg_mask_eq:
   "is_aligned p n \<Longrightarrow> p && ~~ (mask n) = p"
   by (metis add.left_neutral is_aligned_mask word_plus_and_or_coroll2)
 
 lemma is_aligned_shiftr_shiftl:
   "is_aligned w n \<Longrightarrow> w >> n << n = w"
   by (metis and_not_mask is_aligned_neg_mask_eq)
 
 lemma aligned_shiftr_mask_shiftl:
   "is_aligned x n \<Longrightarrow> ((x >> n) && mask v) << n = x && mask (v + n)"
   apply (rule word_eqI)
   apply (simp add: word_size nth_shiftl nth_shiftr)
   apply (subgoal_tac "\<forall>m. x !! m \<longrightarrow> m \<ge> n")
    apply auto[1]
   apply (clarsimp simp: is_aligned_mask)
   apply (drule_tac x=m in word_eqD)
   apply (frule test_bit_size)
   apply (simp add: word_size)
   done
 
 lemma mask_zero:
   "is_aligned x a \<Longrightarrow> x && mask a = 0"
   by (metis is_aligned_mask)
 
 lemma is_aligned_neg_mask_eq_concrete:
   "\<lbrakk> is_aligned p n; msk && ~~(mask n) = ~~(mask n) \<rbrakk>
    \<Longrightarrow> p && msk = p"
   by (metis word_bw_assocs(1) word_bw_comms(1) is_aligned_neg_mask_eq)
 
 lemma is_aligned_and_not_zero:
   "\<lbrakk> is_aligned n k; n \<noteq> 0 \<rbrakk> \<Longrightarrow> 2 ^ k \<le> n"
   using is_aligned_less_sz leI by blast
 
 lemma is_aligned_and_2_to_k:
   "(n && 2 ^ k - 1) = 0 \<Longrightarrow> is_aligned (n :: 'a :: len word) k"
   by (simp add: is_aligned_mask mask_eq_decr_exp)
 
 lemma is_aligned_power2:
   "b \<le> a \<Longrightarrow> is_aligned (2 ^ a) b"
   by (metis is_aligned_triv is_aligned_weaken)
 
 lemma aligned_sub_aligned':
   "\<lbrakk> is_aligned (a :: 'a :: len word) n; is_aligned b n; n < LENGTH('a) \<rbrakk>
    \<Longrightarrow> is_aligned (a - b) n"
   by (simp add: aligned_sub_aligned)
 
 lemma is_aligned_neg_mask_weaken:
   "\<lbrakk> is_aligned p n; m \<le> n \<rbrakk> \<Longrightarrow> p && ~~(mask m) = p"
    using is_aligned_neg_mask_eq is_aligned_weaken by blast
 
 lemma is_aligned_neg_mask2[simp]:
   "is_aligned (a && ~~(mask n)) n"
   by (simp add: and_not_mask is_aligned_shift)
 
 end
diff --git a/thys/Word_Lib/Guide.thy b/thys/Word_Lib/Guide.thy
new file mode 100644
--- /dev/null
+++ b/thys/Word_Lib/Guide.thy
@@ -0,0 +1,295 @@
+(*<*)
+theory Guide
+  imports Main Word_Lemmas Word_Lemmas_32 Word_Lemmas_64
+begin
+
+hide_const (open) Misc_set_bit.set_bit
+
+(*>*)
+section \<open>A short overview over bit operations and word types\<close>
+
+subsection \<open>Basic theories and key ideas\<close>
+
+text \<open>
+  When formalizing bit operations, it is tempting to represent
+  bit values as explicit lists over a binary type. This however
+  is a bad idea, mainly due to the inherent ambiguities in
+  representation concerning repeating leading bits.
+
+  Hence this approach avoids such explicit lists altogether
+  following an algebraic path:
+
+    \<^item> Bit values are represented by numeric types: idealized
+      unbounded bit values can be represented by type \<^typ>\<open>int\<close>,
+      bounded bit values by quotient types over \<^typ>\<open>int\<close>, aka \<^typ>\<open>'a word\<close>.
+
+    \<^item> (A special case are idealized unbounded bit values ending
+      in @{term [source] 0} which can be represented by type \<^typ>\<open>nat\<close> but
+      only support a restricted set of operations).
+
+  The most fundamental ideas are developed in theory \<^theory>\<open>HOL.Parity\<close>
+  (which is part of \<^theory>\<open>Main\<close>):
+
+    \<^item> Multiplication by \<^term>\<open>2 :: int\<close> is a bit shift to the left and
+
+    \<^item> Division by \<^term>\<open>2 :: int\<close> is a bit shift to the right.
+
+    \<^item> Concerning bounded bit values, iterated shifts to the left
+    may result in eliminating all bits by shifting them all
+    beyond the boundary.  The property \<^prop>\<open>(2 :: int) ^ n \<noteq> 0\<close>
+    represents that \<^term>\<open>n\<close> is \<^emph>\<open>not\<close> beyond that boundary.
+
+    \<^item> The projection on a single bit is then @{thm [mode=iff] bit_iff_odd [where ?'a = int, no_vars]}.
+
+    \<^item> This leads to the most fundamental properties of bit values:
+
+      \<^item> Equality rule: @{thm [display, mode=iff] bit_eq_iff [where ?'a = int, no_vars]}
+
+      \<^item> Induction rule: @{thm [display, mode=iff] bits_induct [where ?'a = int, no_vars]}
+
+  On top of this, the following generic operations are provided
+  after import of theory \<^theory>\<open>HOL-Library.Bit_Operations\<close>:
+
+    \<^item> Singleton \<^term>\<open>n\<close>th bit: \<^term>\<open>(2 :: int) ^ n\<close>
+
+    \<^item> Bit mask upto bit \<^term>\<open>n\<close>: @{thm mask_eq_exp_minus_1 [where ?'a = int, no_vars]}
+
+    \<^item> Left shift: @{thm push_bit_eq_mult [where ?'a = int, no_vars]}
+
+    \<^item> Right shift: @{thm drop_bit_eq_div [where ?'a = int, no_vars]}
+
+    \<^item> Truncation: @{thm take_bit_eq_mod [where ?'a = int, no_vars]}
+
+    \<^item> Negation: @{thm [mode=iff] bit_not_iff [where ?'a = int, no_vars]}
+
+    \<^item> And: @{thm [mode=iff] bit_and_iff [where ?'a = int, no_vars]}
+
+    \<^item> Or: @{thm [mode=iff] bit_or_iff [where ?'a = int, no_vars]}
+
+    \<^item> Xor: @{thm [mode=iff] bit_xor_iff [where ?'a = int, no_vars]}
+
+    \<^item> Set a single bit: @{thm set_bit_def [where ?'a = int, no_vars]}
+
+    \<^item> Unset a single bit: @{thm unset_bit_def [where ?'a = int, no_vars]}
+
+    \<^item> Flip a single bit: @{thm flip_bit_def [where ?'a = int, no_vars]}
+
+    \<^item> Signed truncation, or modulus centered around \<^term>\<open>0::int\<close>:
+        @{thm [display] signed_take_bit_def [where ?'a = int, no_vars]}
+
+    \<^item> (Bounded) conversion from and to a list of bits:
+        @{thm [display] horner_sum_bit_eq_take_bit [where ?'a = int, no_vars]}
+
+  Proper word types are introduced in theory \<^theory>\<open>HOL-Word.Word\<close>, with
+  the following specific operations:
+
+    \<^item> Standard arithmetic:
+        @{term \<open>(+) :: 'a::len word \<Rightarrow> 'a word \<Rightarrow> 'a word\<close>},
+        @{term \<open>uminus :: 'a::len word \<Rightarrow> 'a word\<close>},
+        @{term \<open>(-) :: 'a::len word \<Rightarrow> 'a word \<Rightarrow> 'a word\<close>},
+        @{term \<open>(*) :: 'a::len word \<Rightarrow> 'a word \<Rightarrow> 'a word\<close>},
+        @{term \<open>0 :: 'a::len word\<close>}, @{term \<open>1 :: 'a::len word\<close>}, numerals etc.
+
+    \<^item> Standard bit operations: see above.
+
+    \<^item> Conversion with unsigned interpretation of words:
+
+        \<^item> @{term [source] \<open>unsigned :: 'a::len word \<Rightarrow> 'b::semiring_1\<close>}
+
+        \<^item> Important special cases as abbreviations:
+
+            \<^item> @{term [source] \<open>unat :: 'a::len word \<Rightarrow> nat\<close>}
+
+            \<^item> @{term [source] \<open>uint :: 'a::len word \<Rightarrow> int\<close>}
+
+            \<^item> @{term [source] \<open>ucast :: 'a::len word \<Rightarrow> 'b::len word\<close>}
+
+    \<^item> Conversion with signed interpretation of words:
+
+        \<^item> @{term [source] \<open>signed :: 'a::len word \<Rightarrow> 'b::ring_1\<close>}
+
+        \<^item> Important special cases as abbreviations:
+
+            \<^item> @{term [source] \<open>sint :: 'a::len word \<Rightarrow> int\<close>}
+
+            \<^item> @{term [source] \<open>scast :: 'a::len word \<Rightarrow> 'b::len word\<close>}
+
+    \<^item> Operations with unsigned interpretation of words:
+
+        \<^item> @{thm [mode=iff] word_le_nat_alt [no_vars]}
+
+        \<^item> @{thm [mode=iff] word_less_nat_alt [no_vars]}
+
+        \<^item> @{thm unat_div_distrib [no_vars]}
+
+        \<^item> @{thm unat_drop_bit_eq [no_vars]}
+
+        \<^item> @{thm unat_mod_distrib [no_vars]}
+
+        \<^item> @{thm [mode=iff] udvd_iff_dvd [no_vars]}
+
+    \<^item> Operations with with signed interpretation of words:
+
+        \<^item> @{thm [mode=iff] word_sle_eq [no_vars]}
+
+        \<^item> @{thm [mode=iff] word_sless_alt [no_vars]}
+
+        \<^item> @{thm sint_signed_drop_bit_eq [no_vars]}
+
+    \<^item> Rotation and reversal:
+
+        \<^item> @{term [source] \<open>word_rotl :: nat \<Rightarrow> 'a::len word \<Rightarrow> 'a word\<close>}
+
+        \<^item> @{term [source] \<open>word_rotr :: nat \<Rightarrow> 'a::len word \<Rightarrow> 'a word\<close>}
+
+        \<^item> @{term [source] \<open>word_roti :: int \<Rightarrow> 'a::len word \<Rightarrow> 'a word\<close>}
+
+        \<^item> @{term [source] \<open>word_reverse :: 'a::len word \<Rightarrow> 'a word\<close>}
+
+    \<^item> Concatenation: @{term [source, display] \<open>word_cat :: 'a::len word \<Rightarrow> 'b::len word \<Rightarrow> 'c::len word\<close>}
+
+  For proofs about words the following default strategies are applicable:
+
+    \<^item> Using bit extensionality (facts \<^text>\<open>bit_eq_iff\<close>, \<^text>\<open>bit_eqI\<close>).
+
+    \<^item> Using the @{method transfer} method.
+\<close>
+
+subsection \<open>More theories\<close>
+
+text \<open>
+  Note: currently, the theories listed here are hardly separate
+  entites since they import each other in various ways.
+  Always inspect them to understand what you pull in if you
+  want to import one.
+
+    \<^descr>[Syntax]
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Hex_Words\<close>]
+        Printing word numerals as hexadecimal numerals.
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Type_Syntax\<close>]
+        Pretty type-sensitive syntax for cast operations.
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Syntax\<close>]
+        Specific ASCII syntax for prominent bit operations on word.
+
+    \<^descr>[Proof tools]
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Norm_Words\<close>]
+        Rewriting word numerals to normal forms.
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Bitwise\<close>]
+        Method @{method word_bitwise} decomposes word equalities and inequalities into bit propositions.
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_EqI\<close>]
+        Method @{method word_eqI_solve} decomposes word equalities and inequalities into bit propositions.
+
+    \<^descr>[Operations]
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Lib\<close>]
+        Various operations on word, particularly:
+
+          \<^item> @{term [source] \<open>(sdiv) :: 'a::len word \<Rightarrow> 'a word \<Rightarrow> 'a word\<close>}
+
+          \<^item> @{term [source] \<open>(smod) :: 'a::len word \<Rightarrow> 'a word \<Rightarrow> 'a word\<close>}
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Aligned\<close>] \
+
+          \<^item> @{thm [mode=iff] is_aligned_iff_udvd [no_vars]}
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Next\<close>] \
+
+          \<^item> @{thm word_next_unfold [no_vars]}
+
+          \<^item> @{thm word_prev_unfold [no_vars]}
+
+    \<^descr>[Types]
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Signed_Words\<close>]
+
+          Formal tagging of word types with a \<^text>\<open>signed\<close> marker;
+          currently it is not clear what practical relevance
+          this bears.
+
+    \<^descr>[Mechanisms]
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Enum\<close>]
+
+          More on explicit enumeration of word types.
+
+    \<^descr>[Lemmas]
+
+      Collections of lemmas:
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Lemmas\<close>] generic.
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Lemmas_32\<close>] for 32-bit words.
+
+      \<^descr>[\<^theory>\<open>Word_Lib.Word_Lemmas_64\<close>] for 64-bit words.
+\<close>
+
+
+subsection \<open>Legacy theories\<close>
+
+text \<open>
+  The following theories contain material which has been
+  factored out since it is not recommended to use it in
+  new applications, mostly because matters can be expressed
+  succinctly using already existing operations.
+
+  This section gives some indication how to migrate away
+  from those theories.  However theorem coverage may still
+  be terse in some cases.
+
+  \<^descr>[\<^theory>\<open>HOL-Word.Misc_lsb\<close>]
+
+    A mere alias: @{thm [mode=iff] lsb_odd [where ?'a = int, no_vars]}
+
+  \<^descr>[\<^theory>\<open>HOL-Word.Misc_msb\<close>]
+
+    An alias for the most significant bit; suggested replacements:
+
+      \<^item> @{thm [mode=iff] msb_int_def [of k]}
+
+      \<^item> @{thm [mode=iff] word_msb_sint [no_vars]}
+
+      \<^item> @{thm [mode=iff] msb_word_iff_sless_0 [no_vars]}
+
+      \<^item> @{thm [mode=iff] msb_word_iff_bit [no_vars]}
+
+  \<^descr>[\<^theory>\<open>HOL-Word.Misc_set_bit\<close>]
+
+    An alias: @{thm set_bit_eq [no_vars]}
+
+  \<^descr>[\<^theory>\<open>HOL-Word.Misc_Typedef\<close>]
+
+    An invasive low-level extension to HOL typedef to provide
+    conversions along type morphisms.
+
+  \<^descr>[\<^theory>\<open>HOL-Word.Traditional_Syntax\<close>]
+
+    Clones of existing operations decorated with
+    traditional syntax:
+
+      \<^item> @{thm test_bit_eq_bit [no_vars]}
+
+      \<^item> @{thm shiftl_eq_push_bit [no_vars]}
+
+      \<^item> @{thm shiftr_eq_drop_bit [no_vars]}
+
+  \<^descr>[\<^theory>\<open>HOL-Word.Reversed_Bit_Lists\<close>]
+
+    Representation of bit values as explicit list in
+    \<^emph>\<open>reversed\<close> order.
+
+    This should rarely be necessary: the \<^const>\<open>bit\<close> projection
+    should be sufficient in most cases.  In case explicit lists
+    are needed, existing operations can be used:
+
+    @{thm [display] horner_sum_bit_eq_take_bit [where ?'a = int, no_vars]}
+\<close>
+
+(*<*)
+end
+(*>*)
diff --git a/thys/Word_Lib/More_Divides.thy b/thys/Word_Lib/More_Divides.thy
--- a/thys/Word_Lib/More_Divides.thy
+++ b/thys/Word_Lib/More_Divides.thy
@@ -1,55 +1,55 @@
 (*
  * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
  *
  * SPDX-License-Identifier: BSD-2-Clause
  *)
 
 section "More Lemmas on Division"
 
 theory More_Divides
 imports Main
 begin
 
 lemma div_mult_le:
   \<open>a div b * b \<le> a\<close> for a b :: nat
   by (fact div_times_less_eq_dividend)
 
 lemma diff_mod_le:
   \<open>a - a mod b \<le> d - b\<close> if \<open>a < d\<close> \<open>b dvd d\<close> for a b d :: nat
   using that
   apply(subst minus_mod_eq_mult_div)
   apply(clarsimp simp: dvd_def)
-  apply(case_tac "b = 0")
+  apply(cases \<open>b = 0\<close>)
    apply simp
   apply(subgoal_tac "a div b \<le> k - 1")
    prefer 2
    apply(subgoal_tac "a div b < k")
     apply(simp add: less_Suc_eq_le [symmetric])
    apply(subgoal_tac "b * (a div b) < b * ((b * k) div b)")
     apply clarsimp
    apply(subst div_mult_self1_is_m)
     apply arith
    apply(rule le_less_trans)
     apply simp
     apply(subst mult.commute)
     apply(rule div_mult_le)
    apply assumption
   apply clarsimp
   apply(subgoal_tac "b * (a div b) \<le> b * (k - 1)")
    apply(erule le_trans)
    apply(simp add: diff_mult_distrib2)
   apply simp
   done
 
 lemma int_div_same_is_1 [simp]:
   \<open>a div b = a \<longleftrightarrow> b = 1\<close> if \<open>0 < a\<close> for a b :: int
   using that by (metis div_by_1 abs_ge_zero abs_of_pos int_div_less_self neq_iff
             nonneg1_imp_zdiv_pos_iff zabs_less_one_iff)
 
 lemma int_div_minus_is_minus1 [simp]:
   \<open>a div b = - a \<longleftrightarrow> b = - 1\<close> if \<open>0 > a\<close> for a b :: int
   using that by (metis div_minus_right equation_minus_iff int_div_same_is_1 neg_0_less_iff_less)
 
 declare div_eq_dividend_iff [simp]
 
 end
diff --git a/thys/Word_Lib/ROOT b/thys/Word_Lib/ROOT
--- a/thys/Word_Lib/ROOT
+++ b/thys/Word_Lib/ROOT
@@ -1,12 +1,13 @@
 chapter AFP
 
 session Word_Lib (AFP) = "HOL-Word" +
   options [timeout = 300]
   sessions
     "HOL-Eisbach"
   theories
     Word_Lemmas_32
     Word_Lemmas_64
     Examples
+    Guide
   document_files
     "root.tex"
diff --git a/thys/Word_Lib/Word_Lemmas.thy b/thys/Word_Lib/Word_Lemmas.thy
--- a/thys/Word_Lib/Word_Lemmas.thy
+++ b/thys/Word_Lib/Word_Lemmas.thy
@@ -1,6164 +1,6168 @@
 (*
  * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
  *
  * SPDX-License-Identifier: BSD-2-Clause
  *)
 
 section "Lemmas with Generic Word Length"
 
 theory Word_Lemmas
   imports
     "HOL-Library.Sublist"
     "HOL-Word.Misc_lsb"
     Word_EqI
     Word_Enum
     Norm_Words
     Word_Type_Syntax
     Bitwise_Signed
     Hex_Words
 begin
 
+lemmas word_next_def = word_next_unfold
+
+lemmas word_prev_def = word_prev_unfold
+
 lemmas is_aligned_def = is_aligned_iff_dvd_nat
 
 lemma word_plus_mono_left:
   fixes x :: "'a :: len word"
   shows "\<lbrakk>y \<le> z; x \<le> x + z\<rbrakk> \<Longrightarrow> y + x \<le> z + x"
   by unat_arith
 
 lemma word_shiftl_add_distrib:
   fixes x :: "'a :: len word"
   shows "(x + y) << n = (x << n) + (y << n)"
   by (simp add: shiftl_t2n ring_distribs)
 
 lemma less_Suc_unat_less_bound:
   "n < Suc (unat (x :: 'a :: len word)) \<Longrightarrow> n < 2 ^ LENGTH('a)"
   by (auto elim!: order_less_le_trans intro: Suc_leI)
 
 lemma up_ucast_inj:
   "\<lbrakk> ucast x = (ucast y::'b::len word); LENGTH('a) \<le> len_of TYPE ('b) \<rbrakk> \<Longrightarrow> x = (y::'a::len word)"
   by (subst (asm) bang_eq) (fastforce simp: nth_ucast word_size intro: word_eqI)
 
 lemmas ucast_up_inj = up_ucast_inj
 
 lemma up_ucast_inj_eq:
   "LENGTH('a) \<le> len_of TYPE ('b) \<Longrightarrow> (ucast x = (ucast y::'b::len word)) = (x = (y::'a::len word))"
   by (fastforce dest: up_ucast_inj)
 
 lemma no_plus_overflow_neg:
   "(x :: 'a :: len word) < -y \<Longrightarrow> x \<le> x + y"
   by (metis diff_minus_eq_add less_imp_le sub_wrap_lt)
 
 lemma ucast_ucast_eq:
   "\<lbrakk> ucast x = (ucast (ucast y::'a word)::'c::len word); LENGTH('a) \<le> LENGTH('b);
      LENGTH('b) \<le> LENGTH('c) \<rbrakk> \<Longrightarrow>
    x = ucast y" for x :: "'a::len word" and y :: "'b::len word"
   by (fastforce intro: word_eqI simp: bang_eq nth_ucast word_size)
 
 lemma ucast_0_I:
   "x = 0 \<Longrightarrow> ucast x = 0"
   by simp
 
 text \<open>right-padding a word to a certain length\<close>
 
 definition
   "bl_pad_to bl sz \<equiv> bl @ (replicate (sz - length bl) False)"
 
 lemma bl_pad_to_length:
   assumes lbl: "length bl \<le> sz"
   shows   "length (bl_pad_to bl sz) = sz"
   using lbl by (simp add: bl_pad_to_def)
 
 lemma bl_pad_to_prefix:
   "prefix bl (bl_pad_to bl sz)"
   by (simp add: bl_pad_to_def)
 
 lemma same_length_is_parallel:
   assumes len: "\<forall>y \<in> set as. length y = x"
   shows  "\<forall>x \<in> set as. \<forall>y \<in> set as - {x}. x \<parallel> y"
 proof (rule, rule)
   fix x y
   assume xi: "x \<in> set as" and yi: "y \<in> set as - {x}"
   from len obtain q where len': "\<forall>y \<in> set as. length y = q" ..
 
   show "x \<parallel> y"
   proof (rule not_equal_is_parallel)
     from xi yi show "x \<noteq> y" by auto
     from xi yi len' show "length x = length y" by (auto dest: bspec)
   qed
 qed
 
 text \<open>Lemmas about words\<close>
 
 lemmas and_bang = word_and_nth
 
 lemma of_drop_to_bl:
   "of_bl (drop n (to_bl x)) = (x && mask (size x - n))"
   by (simp add: of_bl_drop word_size_bl)
 
 lemma word_add_offset_less:
   fixes x :: "'a :: len word"
   assumes yv: "y < 2 ^ n"
   and     xv: "x < 2 ^ m"
   and     mnv: "sz < LENGTH('a :: len)"
   and    xv': "x < 2 ^ (LENGTH('a :: len) - n)"
   and     mn: "sz = m + n"
   shows   "x * 2 ^ n + y < 2 ^ sz"
 proof (subst mn)
   from mnv mn have nv: "n < LENGTH('a)" and mv: "m < LENGTH('a)"  by auto
 
   have uy: "unat y < 2 ^ n"
     by (rule order_less_le_trans [OF unat_mono [OF yv] order_eq_refl],
         rule unat_power_lower[OF nv])
 
   have ux: "unat x < 2 ^ m"
     by (rule order_less_le_trans [OF unat_mono [OF xv] order_eq_refl],
         rule unat_power_lower[OF mv])
 
   then show "x * 2 ^ n + y < 2 ^ (m + n)" using ux uy nv mnv xv'
     apply (subst word_less_nat_alt)
     apply (subst unat_word_ariths)+
     apply (subst mod_less)
      apply simp
      apply (subst mult.commute)
      apply (rule nat_less_power_trans [OF _ order_less_imp_le [OF nv]])
      apply (rule order_less_le_trans [OF unat_mono [OF xv']])
      apply (cases "n = 0"; simp)
     apply (subst unat_power_lower[OF nv])
     apply (subst mod_less)
      apply (erule order_less_le_trans [OF nat_add_offset_less], assumption)
       apply (rule mn)
      apply simp
     apply (simp add: mn mnv)
     apply (erule nat_add_offset_less; simp)
     done
 qed
 
 lemma word_less_power_trans:
   fixes n :: "'a :: len word"
   assumes nv: "n < 2 ^ (m - k)"
   and     kv: "k \<le> m"
   and     mv: "m < len_of TYPE ('a)"
   shows "2 ^ k * n < 2 ^ m"
   using nv kv mv
   apply -
   apply (subst word_less_nat_alt)
   apply (subst unat_word_ariths)
   apply (subst mod_less)
    apply simp
    apply (rule nat_less_power_trans)
     apply (erule order_less_trans [OF unat_mono])
     apply simp
    apply simp
   apply simp
   apply (rule nat_less_power_trans)
    apply (subst unat_power_lower[where 'a = 'a, symmetric])
     apply simp
    apply (erule unat_mono)
   apply simp
   done
 
 lemma Suc_unat_diff_1:
   fixes x :: "'a :: len word"
   assumes lt: "1 \<le> x"
   shows "Suc (unat (x - 1)) = unat x"
 proof -
   have "0 < unat x"
     by (rule order_less_le_trans [where y = 1], simp, subst unat_1 [symmetric],
         rule iffD1 [OF word_le_nat_alt lt])
 
   then show ?thesis
     by ((subst unat_sub [OF lt])+, simp only:  unat_1)
 qed
 
 lemma word_div_sub:
   fixes x :: "'a :: len word"
   assumes yx: "y \<le> x"
   and     y0: "0 < y"
   shows "(x - y) div y = x div y - 1"
   apply (rule word_unat.Rep_eqD)
   apply (subst unat_div)
   apply (subst unat_sub [OF yx])
   apply (subst unat_sub)
    apply (subst word_le_nat_alt)
    apply (subst unat_div)
    apply (subst le_div_geq)
      apply (rule order_le_less_trans [OF _ unat_mono [OF y0]])
      apply simp
     apply (subst word_le_nat_alt [symmetric], rule yx)
    apply simp
   apply (subst unat_div)
   apply (subst le_div_geq [OF _ iffD1 [OF word_le_nat_alt yx]])
    apply (rule order_le_less_trans [OF _ unat_mono [OF y0]])
    apply simp
   apply simp
   done
 
 lemma word_mult_less_mono1:
   fixes i :: "'a :: len word"
   assumes ij: "i < j"
   and    knz: "0 < k"
   and    ujk: "unat j * unat k < 2 ^ len_of TYPE ('a)"
   shows  "i * k < j * k"
 proof -
   from ij ujk knz have jk: "unat i * unat k < 2 ^ len_of TYPE ('a)"
     by (auto intro: order_less_subst2 simp: word_less_nat_alt elim: mult_less_mono1)
 
   then show ?thesis using ujk knz ij
     by (auto simp: word_less_nat_alt iffD1 [OF unat_mult_lem])
 qed
 
 lemma word_mult_less_dest:
   fixes i :: "'a :: len word"
   assumes ij: "i * k < j * k"
   and    uik: "unat i * unat k < 2 ^ len_of TYPE ('a)"
   and    ujk: "unat j * unat k < 2 ^ len_of TYPE ('a)"
   shows  "i < j"
   using uik ujk ij
   by (auto simp: word_less_nat_alt iffD1 [OF unat_mult_lem] elim: mult_less_mono1)
 
 lemma word_mult_less_cancel:
   fixes k :: "'a :: len word"
   assumes knz: "0 < k"
   and    uik: "unat i * unat k < 2 ^ len_of TYPE ('a)"
   and    ujk: "unat j * unat k < 2 ^ len_of TYPE ('a)"
   shows "(i * k < j * k) = (i < j)"
   by (rule iffI [OF word_mult_less_dest [OF _ uik ujk] word_mult_less_mono1 [OF _ knz ujk]])
 
 lemma Suc_div_unat_helper:
   assumes szv: "sz < LENGTH('a :: len)"
   and   usszv: "us \<le> sz"
   shows "2 ^ (sz - us) = Suc (unat (((2::'a :: len word) ^ sz - 1) div 2 ^ us))"
 proof -
   note usv = order_le_less_trans [OF usszv szv]
 
   from usszv obtain q where qv: "sz = us + q" by (auto simp: le_iff_add)
 
   have "Suc (unat (((2:: 'a word) ^ sz - 1) div 2 ^ us)) =
     (2 ^ us + unat ((2:: 'a word) ^ sz - 1)) div 2 ^ us"
     apply (subst unat_div unat_power_lower[OF usv])+
     apply (subst div_add_self1, simp+)
     done
 
   also have "\<dots> = ((2 ^ us - 1) + 2 ^ sz) div 2 ^ us" using szv
     by (simp add: unat_minus_one)
 
   also have "\<dots> = 2 ^ q + ((2 ^ us - 1) div 2 ^ us)"
     apply (subst qv)
     apply (subst power_add)
     apply (subst div_mult_self2; simp)
     done
 
   also have "\<dots> = 2 ^ (sz - us)" using qv by simp
 
   finally show ?thesis ..
 qed
 
 
 lemma set_enum_word8_def:
   "(set enum::word8 set) = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
                             20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
                             37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
                             54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,
                             71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87,
                             88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103,
                             104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117,
                             118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131,
                             132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145,
                             146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
                             160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173,
                             174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187,
                             188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201,
                             202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215,
                             216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229,
                             230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243,
                             244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255}"
   by eval
 
 lemma set_strip_insert: "\<lbrakk> x \<in> insert a S; x \<noteq> a \<rbrakk> \<Longrightarrow> x \<in> S"
   by simp
 
 lemma word8_exhaust:
   fixes x :: word8
   shows "\<lbrakk>x \<noteq> 0; x \<noteq> 1; x \<noteq> 2; x \<noteq> 3; x \<noteq> 4; x \<noteq> 5; x \<noteq> 6; x \<noteq> 7; x \<noteq> 8; x \<noteq> 9; x \<noteq> 10; x \<noteq> 11; x \<noteq>
           12; x \<noteq> 13; x \<noteq> 14; x \<noteq> 15; x \<noteq> 16; x \<noteq> 17; x \<noteq> 18; x \<noteq> 19; x \<noteq> 20; x \<noteq> 21; x \<noteq> 22; x \<noteq>
           23; x \<noteq> 24; x \<noteq> 25; x \<noteq> 26; x \<noteq> 27; x \<noteq> 28; x \<noteq> 29; x \<noteq> 30; x \<noteq> 31; x \<noteq> 32; x \<noteq> 33; x \<noteq>
           34; x \<noteq> 35; x \<noteq> 36; x \<noteq> 37; x \<noteq> 38; x \<noteq> 39; x \<noteq> 40; x \<noteq> 41; x \<noteq> 42; x \<noteq> 43; x \<noteq> 44; x \<noteq>
           45; x \<noteq> 46; x \<noteq> 47; x \<noteq> 48; x \<noteq> 49; x \<noteq> 50; x \<noteq> 51; x \<noteq> 52; x \<noteq> 53; x \<noteq> 54; x \<noteq> 55; x \<noteq>
           56; x \<noteq> 57; x \<noteq> 58; x \<noteq> 59; x \<noteq> 60; x \<noteq> 61; x \<noteq> 62; x \<noteq> 63; x \<noteq> 64; x \<noteq> 65; x \<noteq> 66; x \<noteq>
           67; x \<noteq> 68; x \<noteq> 69; x \<noteq> 70; x \<noteq> 71; x \<noteq> 72; x \<noteq> 73; x \<noteq> 74; x \<noteq> 75; x \<noteq> 76; x \<noteq> 77; x \<noteq>
           78; x \<noteq> 79; x \<noteq> 80; x \<noteq> 81; x \<noteq> 82; x \<noteq> 83; x \<noteq> 84; x \<noteq> 85; x \<noteq> 86; x \<noteq> 87; x \<noteq> 88; x \<noteq>
           89; x \<noteq> 90; x \<noteq> 91; x \<noteq> 92; x \<noteq> 93; x \<noteq> 94; x \<noteq> 95; x \<noteq> 96; x \<noteq> 97; x \<noteq> 98; x \<noteq> 99; x \<noteq>
           100; x \<noteq> 101; x \<noteq> 102; x \<noteq> 103; x \<noteq> 104; x \<noteq> 105; x \<noteq> 106; x \<noteq> 107; x \<noteq> 108; x \<noteq> 109; x \<noteq>
           110; x \<noteq> 111; x \<noteq> 112; x \<noteq> 113; x \<noteq> 114; x \<noteq> 115; x \<noteq> 116; x \<noteq> 117; x \<noteq> 118; x \<noteq> 119; x \<noteq>
           120; x \<noteq> 121; x \<noteq> 122; x \<noteq> 123; x \<noteq> 124; x \<noteq> 125; x \<noteq> 126; x \<noteq> 127; x \<noteq> 128; x \<noteq> 129; x \<noteq>
           130; x \<noteq> 131; x \<noteq> 132; x \<noteq> 133; x \<noteq> 134; x \<noteq> 135; x \<noteq> 136; x \<noteq> 137; x \<noteq> 138; x \<noteq> 139; x \<noteq>
           140; x \<noteq> 141; x \<noteq> 142; x \<noteq> 143; x \<noteq> 144; x \<noteq> 145; x \<noteq> 146; x \<noteq> 147; x \<noteq> 148; x \<noteq> 149; x \<noteq>
           150; x \<noteq> 151; x \<noteq> 152; x \<noteq> 153; x \<noteq> 154; x \<noteq> 155; x \<noteq> 156; x \<noteq> 157; x \<noteq> 158; x \<noteq> 159; x \<noteq>
           160; x \<noteq> 161; x \<noteq> 162; x \<noteq> 163; x \<noteq> 164; x \<noteq> 165; x \<noteq> 166; x \<noteq> 167; x \<noteq> 168; x \<noteq> 169; x \<noteq>
           170; x \<noteq> 171; x \<noteq> 172; x \<noteq> 173; x \<noteq> 174; x \<noteq> 175; x \<noteq> 176; x \<noteq> 177; x \<noteq> 178; x \<noteq> 179; x \<noteq>
           180; x \<noteq> 181; x \<noteq> 182; x \<noteq> 183; x \<noteq> 184; x \<noteq> 185; x \<noteq> 186; x \<noteq> 187; x \<noteq> 188; x \<noteq> 189; x \<noteq>
           190; x \<noteq> 191; x \<noteq> 192; x \<noteq> 193; x \<noteq> 194; x \<noteq> 195; x \<noteq> 196; x \<noteq> 197; x \<noteq> 198; x \<noteq> 199; x \<noteq>
           200; x \<noteq> 201; x \<noteq> 202; x \<noteq> 203; x \<noteq> 204; x \<noteq> 205; x \<noteq> 206; x \<noteq> 207; x \<noteq> 208; x \<noteq> 209; x \<noteq>
           210; x \<noteq> 211; x \<noteq> 212; x \<noteq> 213; x \<noteq> 214; x \<noteq> 215; x \<noteq> 216; x \<noteq> 217; x \<noteq> 218; x \<noteq> 219; x \<noteq>
           220; x \<noteq> 221; x \<noteq> 222; x \<noteq> 223; x \<noteq> 224; x \<noteq> 225; x \<noteq> 226; x \<noteq> 227; x \<noteq> 228; x \<noteq> 229; x \<noteq>
           230; x \<noteq> 231; x \<noteq> 232; x \<noteq> 233; x \<noteq> 234; x \<noteq> 235; x \<noteq> 236; x \<noteq> 237; x \<noteq> 238; x \<noteq> 239; x \<noteq>
           240; x \<noteq> 241; x \<noteq> 242; x \<noteq> 243; x \<noteq> 244; x \<noteq> 245; x \<noteq> 246; x \<noteq> 247; x \<noteq> 248; x \<noteq> 249; x \<noteq>
           250; x \<noteq> 251; x \<noteq> 252; x \<noteq> 253; x \<noteq> 254; x \<noteq> 255\<rbrakk> \<Longrightarrow> P"
   apply (subgoal_tac "x \<in> set enum", subst (asm) set_enum_word8_def)
     apply (drule set_strip_insert, assumption)+
    apply (erule emptyE)
   apply (subst enum_UNIV, rule UNIV_I)
   done
 
 lemma upto_enum_red':
   assumes lt: "1 \<le> X"
   shows "[(0::'a :: len word) .e. X - 1] =  map of_nat [0 ..< unat X]"
 proof -
   have lt': "unat X < 2 ^ LENGTH('a)"
     by (rule unat_lt2p)
 
   show ?thesis
     apply (subst upto_enum_red)
     apply (simp del: upt.simps)
     apply (subst Suc_unat_diff_1 [OF lt])
     apply (rule map_cong [OF refl])
     apply (rule toEnum_of_nat)
     apply simp
     apply (erule order_less_trans [OF _ lt'])
     done
 qed
 
 lemma upto_enum_red2:
   assumes szv: "sz < LENGTH('a :: len)"
   shows "[(0:: 'a :: len word) .e. 2 ^ sz - 1] =
   map of_nat [0 ..< 2 ^ sz]" using szv
   apply (subst unat_power_lower[OF szv, symmetric])
   apply (rule upto_enum_red')
   apply (subst word_le_nat_alt, simp)
   done
 
 lemma upto_enum_step_red:
   assumes szv: "sz < LENGTH('a)"
   and   usszv: "us \<le> sz"
   shows "[0 :: 'a :: len word , 2 ^ us .e. 2 ^ sz - 1] =
   map (\<lambda>x. of_nat x * 2 ^ us) [0 ..< 2 ^ (sz - us)]" using szv
   unfolding upto_enum_step_def
   apply (subst if_not_P)
    apply (rule leD)
    apply (subst word_le_nat_alt)
    apply (subst unat_minus_one)
     apply simp
    apply simp
   apply simp
   apply (subst upto_enum_red)
   apply (simp del: upt.simps)
   apply (subst Suc_div_unat_helper [where 'a = 'a, OF szv usszv, symmetric])
   apply clarsimp
   apply (subst toEnum_of_nat)
    apply (erule order_less_trans)
    using szv
    apply simp
   apply simp
   done
 
 lemma upto_enum_word:
   "[x .e. y] = map of_nat [unat x ..< Suc (unat y)]"
   apply (subst upto_enum_red)
   apply clarsimp
   apply (subst toEnum_of_nat)
    prefer 2
    apply (rule refl)
   apply (erule disjE, simp)
   apply clarsimp
   apply (erule order_less_trans)
   apply simp
   done
 
 lemma word_upto_Cons_eq:
   "x < y \<Longrightarrow> [x::'a::len word .e. y] = x # [x + 1 .e. y]"
   apply (subst upto_enum_red)
   apply (subst upt_conv_Cons)
   apply simp_all
    apply unat_arith
   apply (simp only: list.map list.inject upto_enum_red to_from_enum simp_thms)
   apply simp_all
   apply unat_arith
   done
 
 lemma distinct_enum_upto:
   "distinct [(0 :: 'a::len word) .e. b]"
 proof -
   have "\<And>(b::'a word). [0 .e. b] = nths enum {..< Suc (fromEnum b)}"
     apply (subst upto_enum_red)
     apply (subst nths_upt_eq_take)
     apply (subst enum_word_def)
     apply (subst take_map)
     apply (subst take_upt)
      apply (simp only: add_0 fromEnum_unat)
      apply (rule order_trans [OF _ order_eq_refl])
       apply (rule Suc_leI [OF unat_lt2p])
      apply simp
     apply clarsimp
     apply (rule toEnum_of_nat)
     apply (erule order_less_trans [OF _ unat_lt2p])
     done
 
   then show ?thesis
     by (rule ssubst) (rule distinct_nthsI, simp)
 qed
 
 lemma upto_enum_set_conv [simp]:
   fixes a :: "'a :: len word"
   shows "set [a .e. b] = {x. a \<le> x \<and> x \<le> b}"
   apply (subst upto_enum_red)
   apply (subst set_map)
   apply safe
     apply simp
     apply clarsimp
     apply (erule disjE)
      apply simp
      apply (erule iffD2 [OF word_le_nat_alt])
     apply clarsimp
     apply (erule word_unat.Rep_cases [OF unat_le [OF order_less_imp_le]])
     apply simp
     apply (erule iffD2 [OF word_le_nat_alt])
    apply simp
 
    apply clarsimp
    apply (erule disjE)
     apply simp
    apply clarsimp
    apply (rule word_unat.Rep_cases [OF unat_le  [OF order_less_imp_le]])
     apply assumption
    apply simp
    apply (erule order_less_imp_le [OF iffD2 [OF word_less_nat_alt]])
   apply clarsimp
   apply (rule_tac x="fromEnum x" in image_eqI)
    apply clarsimp
   apply clarsimp
   apply (rule conjI)
    apply (subst word_le_nat_alt [symmetric])
    apply simp
   apply safe
    apply (simp add: word_le_nat_alt [symmetric])
   apply (simp add: word_less_nat_alt [symmetric])
   done
 
 lemma upto_enum_less:
   assumes xin: "x \<in> set [(a::'a::len word).e.2 ^ n - 1]"
   and     nv:  "n < LENGTH('a::len)"
   shows   "x < 2 ^ n"
 proof (cases n)
   case 0
   then show ?thesis using xin by simp
 next
   case (Suc m)
   show ?thesis using xin nv by simp
 qed
 
 lemma upto_enum_len_less:
   "\<lbrakk> n \<le> length [a, b .e. c]; n \<noteq> 0 \<rbrakk> \<Longrightarrow> a \<le> c"
   unfolding upto_enum_step_def
   by (simp split: if_split_asm)
 
 lemma length_upto_enum_step:
   fixes x :: "'a :: len word"
   shows "x \<le> z \<Longrightarrow> length [x , y .e. z] = (unat ((z - x) div (y - x))) + 1"
   unfolding upto_enum_step_def
   by (simp add: upto_enum_red)
 
 lemma map_length_unfold_one:
   fixes x :: "'a::len word"
   assumes xv: "Suc (unat x) < 2 ^ LENGTH('a)"
   and     ax: "a < x"
   shows   "map f [a .e. x] = f a # map f [a + 1 .e. x]"
   by (subst word_upto_Cons_eq, auto, fact+)
 
 lemma upto_enum_set_conv2:
   fixes a :: "'a::len word"
   shows "set [a .e. b] = {a .. b}"
   by auto
 
 lemma of_nat_unat [simp]:
   "of_nat \<circ> unat = id"
   by (rule ext, simp)
 
 lemma Suc_unat_minus_one [simp]:
   "x \<noteq> 0 \<Longrightarrow> Suc (unat (x - 1)) = unat x"
   by (metis Suc_diff_1 unat_gt_0 unat_minus_one)
 
 lemma word_add_le_dest:
   fixes i :: "'a :: len word"
   assumes le: "i + k \<le> j + k"
   and    uik: "unat i + unat k < 2 ^ len_of TYPE ('a)"
   and    ujk: "unat j + unat k < 2 ^ len_of TYPE ('a)"
   shows  "i \<le> j"
   using uik ujk le
   by (auto simp: word_le_nat_alt iffD1 [OF unat_add_lem] elim: add_le_mono1)
 
 lemma mask_shift:
   "(x && ~~ (mask y)) >> y = x >> y"
   by word_eqI
 
 lemma word_add_le_mono1:
   fixes i :: "'a :: len word"
   assumes ij: "i \<le> j"
   and    ujk: "unat j + unat k < 2 ^ len_of TYPE ('a)"
   shows  "i + k \<le> j + k"
 proof -
   from ij ujk have jk: "unat i + unat k < 2 ^ len_of TYPE ('a)"
     by (auto elim: order_le_less_subst2 simp: word_le_nat_alt elim: add_le_mono1)
 
   then show ?thesis using ujk ij
     by (auto simp: word_le_nat_alt iffD1 [OF unat_add_lem])
 qed
 
 lemma word_add_le_mono2:
   fixes i :: "'a :: len word"
   shows "\<lbrakk>i \<le> j; unat j + unat k < 2 ^ LENGTH('a)\<rbrakk> \<Longrightarrow> k + i \<le> k + j"
   by (subst field_simps, subst field_simps, erule (1) word_add_le_mono1)
 
 lemma word_add_le_iff:
   fixes i :: "'a :: len word"
   assumes uik: "unat i + unat k < 2 ^ len_of TYPE ('a)"
   and     ujk: "unat j + unat k < 2 ^ len_of TYPE ('a)"
   shows  "(i + k \<le> j + k) = (i \<le> j)"
 proof
   assume "i \<le> j"
   show "i + k \<le> j + k" by (rule word_add_le_mono1) fact+
 next
   assume "i + k \<le> j + k"
   show "i \<le> j" by (rule word_add_le_dest) fact+
 qed
 
 lemma word_add_less_mono1:
   fixes i :: "'a :: len word"
   assumes ij: "i < j"
   and    ujk: "unat j + unat k < 2 ^ len_of TYPE ('a)"
   shows  "i + k < j + k"
 proof -
   from ij ujk have jk: "unat i + unat k < 2 ^ len_of TYPE ('a)"
     by (auto elim: order_le_less_subst2 simp: word_less_nat_alt elim: add_less_mono1)
 
   then show ?thesis using ujk ij
     by (auto simp: word_less_nat_alt iffD1 [OF unat_add_lem])
 qed
 
 lemma word_add_less_dest:
   fixes i :: "'a :: len word"
   assumes le: "i + k < j + k"
   and    uik: "unat i + unat k < 2 ^ len_of TYPE ('a)"
   and    ujk: "unat j + unat k < 2 ^ len_of TYPE ('a)"
   shows  "i < j"
   using uik ujk le
   by (auto simp: word_less_nat_alt iffD1 [OF unat_add_lem] elim: add_less_mono1)
 
 lemma word_add_less_iff:
   fixes i :: "'a :: len word"
   assumes uik: "unat i + unat k < 2 ^ len_of TYPE ('a)"
   and     ujk: "unat j + unat k < 2 ^ len_of TYPE ('a)"
   shows  "(i + k < j + k) = (i < j)"
 proof
   assume "i < j"
   show "i + k < j + k" by (rule word_add_less_mono1) fact+
 next
   assume "i + k < j + k"
   show "i < j" by (rule word_add_less_dest) fact+
 qed
 
 lemma shiftr_div_2n':
   "unat (w >> n) = unat w div 2 ^ n"
   apply (unfold unat_eq_nat_uint)
   apply (subst shiftr_div_2n)
   apply (subst nat_div_distrib)
    apply simp
   apply (simp add: nat_power_eq)
   done
 
 lemma shiftl_shiftr_id:
   assumes nv: "n < LENGTH('a)"
   and     xv: "x < 2 ^ (LENGTH('a) - n)"
   shows "x << n >> n = (x::'a::len word)"
   apply (simp add: shiftl_t2n)
   apply (rule word_unat.Rep_eqD)
   apply (subst shiftr_div_2n')
   apply (cases n)
    apply simp
   apply (subst iffD1 [OF unat_mult_lem])+
    apply (subst unat_power_lower[OF nv])
    apply (rule nat_less_power_trans [OF _ order_less_imp_le [OF nv]])
    apply (rule order_less_le_trans [OF unat_mono [OF xv] order_eq_refl])
    apply (rule unat_power_lower)
    apply simp
   apply (subst unat_power_lower[OF nv])
   apply simp
   done
 
 lemma ucast_shiftl_eq_0:
   fixes w :: "'a :: len word"
   shows "\<lbrakk> n \<ge> LENGTH('b) \<rbrakk> \<Longrightarrow> ucast (w << n) = (0 :: 'b :: len word)"
   by (case_tac "size w \<le> n", clarsimp simp: shiftl_zero_size)
      (clarsimp simp: not_le ucast_bl bl_shiftl bang_eq test_bit_of_bl rev_nth nth_append)
 
 lemma word_mult_less_iff:
   fixes i :: "'a :: len word"
   assumes knz: "0 < k"
   and     uik: "unat i * unat k < 2 ^ len_of TYPE ('a)"
   and     ujk: "unat j * unat k < 2 ^ len_of TYPE ('a)"
   shows  "(i * k < j * k) = (i < j)"
   using assms by (rule word_mult_less_cancel)
 
 lemma word_le_imp_diff_le:
   fixes n :: "'a::len word"
   shows "\<lbrakk>k \<le> n; n \<le> m\<rbrakk> \<Longrightarrow> n - k \<le> m"
   by (auto simp: unat_sub word_le_nat_alt)
 
 lemma word_less_imp_diff_less:
   fixes n :: "'a::len word"
   shows "\<lbrakk>k \<le> n; n < m\<rbrakk> \<Longrightarrow> n - k < m"
   by (clarsimp simp: unat_sub word_less_nat_alt
              intro!: less_imp_diff_less)
 
 lemma word_mult_le_mono1:
   fixes i :: "'a :: len word"
   assumes ij: "i \<le> j"
   and    knz: "0 < k"
   and    ujk: "unat j * unat k < 2 ^ len_of TYPE ('a)"
   shows  "i * k \<le> j * k"
 proof -
   from ij ujk knz have jk: "unat i * unat k < 2 ^ len_of TYPE ('a)"
     by (auto elim: order_le_less_subst2 simp: word_le_nat_alt elim: mult_le_mono1)
 
   then show ?thesis using ujk knz ij
     by (auto simp: word_le_nat_alt iffD1 [OF unat_mult_lem])
 qed
 
 lemma word_mult_le_iff:
   fixes i :: "'a :: len word"
   assumes knz: "0 < k"
   and     uik: "unat i * unat k < 2 ^ len_of TYPE ('a)"
   and     ujk: "unat j * unat k < 2 ^ len_of TYPE ('a)"
   shows  "(i * k \<le> j * k) = (i \<le> j)"
 proof
   assume "i \<le> j"
   show "i * k \<le> j * k" by (rule word_mult_le_mono1) fact+
 next
   assume p: "i * k \<le> j * k"
 
   have "0 < unat k" using knz by (simp add: word_less_nat_alt)
   then show "i \<le> j" using p
     by (clarsimp simp: word_le_nat_alt iffD1 [OF unat_mult_lem uik]
       iffD1 [OF unat_mult_lem ujk])
 qed
 
 lemma word_diff_less:
   fixes n :: "'a :: len word"
   shows "\<lbrakk>0 < n; 0 < m; n \<le> m\<rbrakk> \<Longrightarrow> m - n < m"
   apply (subst word_less_nat_alt)
   apply (subst unat_sub)
    apply assumption
   apply (rule diff_less)
    apply (simp_all add: word_less_nat_alt)
    done
 
 lemma MinI:
   assumes fa: "finite A"
   and     ne: "A \<noteq> {}"
   and     xv: "m \<in> A"
   and    min: "\<forall>y \<in> A. m \<le> y"
   shows "Min A = m" using fa ne xv min
 proof (induct A arbitrary: m rule: finite_ne_induct)
   case singleton then show ?case by simp
 next
   case (insert y F)
 
   from insert.prems have yx: "m \<le> y" and fx: "\<forall>y \<in> F. m \<le> y" by auto
   have "m \<in> insert y F" by fact
   then show ?case
   proof
     assume mv: "m = y"
 
     have mlt: "m \<le> Min F"
       by (rule iffD2 [OF Min_ge_iff [OF insert.hyps(1) insert.hyps(2)] fx])
 
     show ?case
       apply (subst Min_insert [OF insert.hyps(1) insert.hyps(2)])
       apply (subst mv [symmetric])
       apply (auto simp: min_def mlt)
       done
   next
     assume "m \<in> F"
     then have mf: "Min F = m"
       by (rule insert.hyps(4) [OF _ fx])
 
     show ?case
       apply (subst Min_insert [OF insert.hyps(1) insert.hyps(2)])
       apply (subst mf)
       apply (rule iffD2 [OF _ yx])
       apply (auto simp: min_def)
       done
   qed
 qed
 
 lemma length_upto_enum [simp]:
   fixes a :: "'a :: len word"
   shows "length [a .e. b] = Suc (unat b) - unat a"
   apply (simp add: word_le_nat_alt upto_enum_red)
   apply (clarsimp simp: Suc_diff_le)
   done
 
 lemma length_upto_enum_cases:
   fixes a :: "'a::len word"
   shows "length [a .e. b] = (if a \<le> b then Suc (unat b) - unat a else 0)"
   apply (case_tac "a \<le> b")
    apply (clarsimp)
   apply (clarsimp simp: upto_enum_def)
   apply unat_arith
   done
 
 lemma length_upto_enum_less_one:
   "\<lbrakk>a \<le> b; b \<noteq> 0\<rbrakk>
   \<Longrightarrow> length [a .e. b - 1] = unat (b - a)"
   apply clarsimp
   apply (subst unat_sub[symmetric], assumption)
   apply clarsimp
   done
 
 lemma drop_upto_enum:
   "drop (unat n) [0 .e. m] = [n .e. m]"
   apply (clarsimp simp: upto_enum_def)
   apply (induct m, simp)
   by (metis drop_map drop_upt plus_nat.add_0)
 
 lemma distinct_enum_upto' [simp]:
   "distinct [a::'a::len word .e. b]"
   apply (subst drop_upto_enum [symmetric])
   apply (rule distinct_drop)
   apply (rule distinct_enum_upto)
   done
 
 lemma length_interval:
   "\<lbrakk>set xs = {x. (a::'a::len word) \<le> x \<and> x \<le> b}; distinct xs\<rbrakk>
   \<Longrightarrow> length xs = Suc (unat b) - unat a"
   apply (frule distinct_card)
   apply (subgoal_tac "set xs = set [a .e. b]")
    apply (cut_tac distinct_card [where xs="[a .e. b]"])
     apply (subst (asm) length_upto_enum)
     apply clarsimp
    apply (rule distinct_enum_upto')
   apply simp
   done
 
 lemma not_empty_eq:
   "(S \<noteq> {}) = (\<exists>x. x \<in> S)"
   by auto
 
 lemma range_subset_lower:
   fixes c :: "'a ::linorder"
   shows "\<lbrakk> {a..b} \<subseteq> {c..d}; x \<in> {a..b} \<rbrakk> \<Longrightarrow> c \<le> a"
   apply (frule (1) subsetD)
   apply (rule classical)
   apply clarsimp
   done
 
 lemma range_subset_upper:
   fixes c :: "'a ::linorder"
   shows "\<lbrakk> {a..b} \<subseteq> {c..d}; x \<in> {a..b} \<rbrakk> \<Longrightarrow> b \<le> d"
   apply (frule (1) subsetD)
   apply (rule classical)
   apply clarsimp
   done
 
 lemma range_subset_eq:
   fixes a::"'a::linorder"
   assumes non_empty: "a \<le> b"
   shows "({a..b} \<subseteq> {c..d}) = (c \<le> a \<and> b \<le> d)"
   apply (insert non_empty)
   apply (rule iffI)
    apply (frule range_subset_lower [where x=a], simp)
    apply (drule range_subset_upper [where x=a], simp)
    apply simp
   apply auto
   done
 
 lemma range_eq:
   fixes a::"'a::linorder"
   assumes non_empty: "a \<le> b"
   shows "({a..b} = {c..d}) = (a = c \<and> b = d)"
   by (metis atLeastatMost_subset_iff eq_iff non_empty)
 
 lemma range_strict_subset_eq:
   fixes a::"'a::linorder"
   assumes non_empty: "a \<le> b"
   shows "({a..b} \<subset> {c..d}) = (c \<le> a \<and> b \<le> d \<and> (a = c \<longrightarrow> b \<noteq> d))"
   apply (insert non_empty)
   apply (subst psubset_eq)
   apply (subst range_subset_eq, assumption+)
   apply (subst range_eq, assumption+)
   apply simp
   done
 
 lemma range_subsetI:
   fixes x :: "'a :: order"
   assumes xX: "X \<le> x"
   and     yY: "y \<le> Y"
   shows   "{x .. y} \<subseteq> {X .. Y}"
   using xX yY by auto
 
 lemma set_False [simp]:
   "(set bs \<subseteq> {False}) = (True \<notin> set bs)" by auto
 
 declare of_nat_power [simp del]
 
 (* TODO: move to word *)
 lemma unat_of_bl_length:
   "unat (of_bl xs :: 'a::len word) < 2 ^ (length xs)"
 proof (cases "length xs < LENGTH('a)")
   case True
   then have "(of_bl xs::'a::len word) < 2 ^ length xs"
     by (simp add: of_bl_length_less)
   with True
   show ?thesis
     by (simp add: word_less_nat_alt word_unat_power unat_of_nat)
 next
   case False
   have "unat (of_bl xs::'a::len word) < 2 ^ LENGTH('a)"
     by (simp split: unat_split)
   also
   from False
   have "LENGTH('a) \<le> length xs" by simp
   then have "2 ^ LENGTH('a) \<le> (2::nat) ^ length xs"
     by (rule power_increasing) simp
   finally
   show ?thesis .
 qed
 
 lemma is_aligned_0'[simp]:
   "is_aligned 0 n"
   by (simp add: is_aligned_def)
 
 lemma p_assoc_help:
   fixes p :: "'a::{ring,power,numeral,one}"
   shows "p + 2^sz - 1 = p + (2^sz - 1)"
   by simp
 
 lemma word_add_increasing:
   fixes x :: "'a :: len word"
   shows "\<lbrakk> p + w \<le> x; p \<le> p + w \<rbrakk> \<Longrightarrow> p \<le> x"
   by unat_arith
 
 lemma word_random:
   fixes x :: "'a :: len word"
   shows "\<lbrakk> p \<le> p + x'; x \<le> x' \<rbrakk> \<Longrightarrow> p \<le> p + x"
   by unat_arith
 
 lemma word_sub_mono:
   "\<lbrakk> a \<le> c; d \<le> b; a - b \<le> a; c - d \<le> c \<rbrakk>
     \<Longrightarrow> (a - b) \<le> (c - d :: 'a :: len word)"
   by unat_arith
 
 lemma power_not_zero:
   "n < LENGTH('a::len) \<Longrightarrow> (2 :: 'a word) ^ n \<noteq> 0"
   by (metis p2_gt_0 word_neq_0_conv)
 
 lemma word_gt_a_gt_0:
   "a < n \<Longrightarrow> (0 :: 'a::len word) < n"
   apply (case_tac "n = 0")
    apply clarsimp
   apply (clarsimp simp: word_neq_0_conv)
   done
 
 lemma word_shift_nonzero:
   "\<lbrakk> (x::'a::len word) \<le> 2 ^ m; m + n < LENGTH('a::len); x \<noteq> 0\<rbrakk>
    \<Longrightarrow> x << n \<noteq> 0"
   apply (simp only: word_neq_0_conv word_less_nat_alt
                     shiftl_t2n mod_0 unat_word_ariths
                     unat_power_lower word_le_nat_alt)
   apply (subst mod_less)
    apply (rule order_le_less_trans)
     apply (erule mult_le_mono2)
    apply (subst power_add[symmetric])
    apply (rule power_strict_increasing)
     apply simp
    apply simp
   apply simp
   done
 
 lemma word_power_less_1 [simp]:
   "sz < LENGTH('a::len) \<Longrightarrow> (2::'a word) ^ sz - 1 < 2 ^ sz"
   apply (simp add: word_less_nat_alt)
   apply (subst unat_minus_one)
   apply (simp add: word_unat.Rep_inject [symmetric])
   apply simp
   done
 
 lemma nasty_split_lt:
   "\<lbrakk> (x :: 'a:: len word) < 2 ^ (m - n); n \<le> m; m < LENGTH('a::len) \<rbrakk>
      \<Longrightarrow> x * 2 ^ n + (2 ^ n - 1) \<le> 2 ^ m - 1"
   apply (simp only: add_diff_eq)
   apply (subst mult_1[symmetric], subst distrib_right[symmetric])
   apply (rule word_sub_mono)
      apply (rule order_trans)
       apply (rule word_mult_le_mono1)
         apply (rule inc_le)
         apply assumption
        apply (subst word_neq_0_conv[symmetric])
        apply (rule power_not_zero)
        apply simp
       apply (subst unat_power_lower, simp)+
       apply (subst power_add[symmetric])
       apply (rule power_strict_increasing)
        apply simp
       apply simp
      apply (subst power_add[symmetric])
      apply simp
     apply simp
    apply (rule word_sub_1_le)
    apply (subst mult.commute)
    apply (subst shiftl_t2n[symmetric])
    apply (rule word_shift_nonzero)
      apply (erule inc_le)
     apply simp
    apply (unat_arith)
   apply (drule word_power_less_1)
   apply simp
   done
 
 lemma nasty_split_less:
   "\<lbrakk>m \<le> n; n \<le> nm; nm < LENGTH('a::len); x < 2 ^ (nm - n)\<rbrakk>
    \<Longrightarrow> (x :: 'a word) * 2 ^ n + (2 ^ m - 1) < 2 ^ nm"
   apply (simp only: word_less_sub_le[symmetric])
   apply (rule order_trans [OF _ nasty_split_lt])
      apply (rule word_plus_mono_right)
       apply (rule word_sub_mono)
          apply (simp add: word_le_nat_alt)
         apply simp
        apply (simp add: word_sub_1_le[OF power_not_zero])
       apply (simp add: word_sub_1_le[OF power_not_zero])
      apply (rule is_aligned_no_wrap')
       apply (rule is_aligned_mult_triv2)
      apply simp
     apply (erule order_le_less_trans, simp)
    apply simp+
   done
 
 lemma int_not_emptyD:
   "A \<inter> B \<noteq> {} \<Longrightarrow> \<exists>x. x \<in> A \<and> x \<in> B"
   by (erule contrapos_np, clarsimp simp: disjoint_iff_not_equal)
 
 lemma unat_less_power:
   fixes k :: "'a::len word"
   assumes szv: "sz < LENGTH('a)"
   and     kv:  "k < 2 ^ sz"
   shows   "unat k < 2 ^ sz"
   using szv unat_mono [OF kv] by simp
 
 lemma unat_mult_power_lem:
   assumes kv: "k < 2 ^ (LENGTH('a::len) - sz)"
   shows "unat (2 ^ sz * of_nat k :: (('a::len) word)) = 2 ^ sz * k"
 proof (cases \<open>sz < LENGTH('a)\<close>)
   case True
   with assms show ?thesis
     by (simp add: unat_word_ariths take_bit_eq_mod mod_simps)
       (simp add: take_bit_nat_eq_self_iff nat_less_power_trans flip: take_bit_eq_mod)
 next
   case False
   with assms show ?thesis
     by simp
 qed
 
 lemma aligned_add_offset_no_wrap:
   fixes off :: "('a::len) word"
   and     x :: "'a word"
   assumes al: "is_aligned x sz"
   and   offv: "off < 2 ^ sz"
   shows  "unat x + unat off < 2 ^ LENGTH('a)"
 proof cases
   assume szv: "sz < LENGTH('a)"
   from al obtain k where xv: "x = 2 ^ sz * (of_nat k)"
     and kl: "k < 2 ^ (LENGTH('a) - sz)"
     by (auto elim: is_alignedE)
 
   show ?thesis using szv
     apply (subst xv)
     apply (subst unat_mult_power_lem[OF kl])
     apply (subst mult.commute, rule nat_add_offset_less)
       apply (rule less_le_trans[OF unat_mono[OF offv, simplified]])
       apply (erule eq_imp_le[OF unat_power_lower])
      apply (rule kl)
     apply simp
    done
 next
   assume "\<not> sz < LENGTH('a)"
   with offv show ?thesis by (simp add: not_less power_overflow )
 qed
 
 lemma aligned_add_offset_mod:
   fixes x :: "('a::len) word"
   assumes al: "is_aligned x sz"
   and     kv: "k < 2 ^ sz"
   shows   "(x + k) mod 2 ^ sz = k"
 proof cases
   assume szv: "sz < LENGTH('a)"
 
   have ux: "unat x + unat k < 2 ^ LENGTH('a)"
     by (rule aligned_add_offset_no_wrap) fact+
 
   show ?thesis using al szv
     apply -
     apply (erule is_alignedE)
     apply (subst word_unat.Rep_inject [symmetric])
     apply (subst unat_mod)
     apply (subst iffD1 [OF unat_add_lem], rule ux)
     apply simp
     apply (subst unat_mult_power_lem, assumption+)
     apply (simp)
     apply (rule mod_less[OF less_le_trans[OF unat_mono], OF kv])
     apply (erule eq_imp_le[OF unat_power_lower])
     done
 next
   assume "\<not> sz < LENGTH('a)"
   with al show ?thesis
     by (simp add: not_less power_overflow is_aligned_mask mask_eq_decr_exp
                   word_mod_by_0)
 qed
 
 lemma word_plus_mcs_4:
   "\<lbrakk>v + x \<le> w + x; x \<le> v + x\<rbrakk> \<Longrightarrow> v \<le> (w::'a::len word)"
   by uint_arith
 
 lemma word_plus_mcs_3:
   "\<lbrakk>v \<le> w; x \<le> w + x\<rbrakk> \<Longrightarrow> v + x \<le> w + (x::'a::len word)"
   by unat_arith
 
 lemma aligned_neq_into_no_overlap:
   fixes x :: "'a::len word"
   assumes neq: "x \<noteq> y"
   and     alx: "is_aligned x sz"
   and     aly: "is_aligned y sz"
   shows  "{x .. x + (2 ^ sz - 1)} \<inter> {y .. y + (2 ^ sz - 1)} = {}"
 proof cases
   assume szv: "sz < LENGTH('a)"
   show ?thesis
   proof (rule equals0I, clarsimp)
     fix z
     assume xb: "x \<le> z" and xt: "z \<le> x + (2 ^ sz - 1)"
       and yb: "y \<le> z" and yt: "z \<le> y + (2 ^ sz - 1)"
 
     have rl: "\<And>(p::'a word) k w. \<lbrakk>uint p + uint k < 2 ^ LENGTH('a); w = p + k; w \<le> p + (2 ^ sz - 1) \<rbrakk>
       \<Longrightarrow> k < 2 ^ sz"
       apply -
       apply simp
       apply (subst (asm) add.commute, subst (asm) add.commute, drule word_plus_mcs_4)
       apply (subst add.commute, subst no_plus_overflow_uint_size)
       apply (simp add: word_size_bl)
       apply (erule iffD1 [OF word_less_sub_le[OF szv]])
       done
 
     from xb obtain kx where
       kx: "z = x + kx" and
       kxl: "uint x + uint kx < 2 ^ LENGTH('a)"
       by (clarsimp dest!: word_le_exists')
 
     from yb obtain ky where
       ky: "z = y + ky" and
       kyl: "uint y + uint ky < 2 ^ LENGTH('a)"
       by (clarsimp dest!: word_le_exists')
 
     have "x = y"
     proof -
       have "kx = z mod 2 ^ sz"
       proof (subst kx, rule sym, rule aligned_add_offset_mod)
         show "kx < 2 ^ sz" by (rule rl) fact+
       qed fact+
 
       also have "\<dots> = ky"
       proof (subst ky, rule aligned_add_offset_mod)
         show "ky < 2 ^ sz"
           using kyl ky yt by (rule rl)
       qed fact+
 
       finally have kxky: "kx = ky" .
       moreover have "x + kx = y + ky" by (simp add: kx [symmetric] ky [symmetric])
       ultimately show ?thesis by simp
     qed
 
     then show False using neq by simp
   qed
 next
   assume "\<not> sz < LENGTH('a)"
   with neq alx aly
   have False by (simp add: is_aligned_mask mask_eq_decr_exp power_overflow)
   then show ?thesis ..
 qed
 
 lemma less_two_pow_divD:
   "\<lbrakk> (x :: nat) < 2 ^ n div 2 ^ m \<rbrakk>
     \<Longrightarrow> n \<ge> m \<and> (x < 2 ^ (n - m))"
   apply (rule context_conjI)
    apply (rule ccontr)
    apply (simp add: power_strict_increasing)
   apply (simp add: power_sub)
   done
 
 lemma less_two_pow_divI:
   "\<lbrakk> (x :: nat) < 2 ^ (n - m); m \<le> n \<rbrakk> \<Longrightarrow> x < 2 ^ n div 2 ^ m"
   by (simp add: power_sub)
 
 lemma word_less_two_pow_divI:
   "\<lbrakk> (x :: 'a::len word) < 2 ^ (n - m); m \<le> n; n < LENGTH('a) \<rbrakk> \<Longrightarrow> x < 2 ^ n div 2 ^ m"
   apply (simp add: word_less_nat_alt)
   apply (subst unat_word_ariths)
   apply (subst mod_less)
    apply (rule order_le_less_trans [OF div_le_dividend])
    apply (rule unat_lt2p)
   apply (simp add: power_sub)
   done
 
 lemma word_less_two_pow_divD:
   "\<lbrakk> (x :: 'a::len word) < 2 ^ n div 2 ^ m \<rbrakk>
      \<Longrightarrow> n \<ge> m \<and> (x < 2 ^ (n - m))"
   apply (cases "n < LENGTH('a)")
    apply (cases "m < LENGTH('a)")
     apply (simp add: word_less_nat_alt)
     apply (subst(asm) unat_word_ariths)
     apply (subst(asm) mod_less)
      apply (rule order_le_less_trans [OF div_le_dividend])
      apply (rule unat_lt2p)
     apply (clarsimp dest!: less_two_pow_divD)
    apply (simp add: power_overflow)
    apply (simp add: word_div_def)
   apply (simp add: power_overflow word_div_def)
   done
 
 lemma of_nat_less_two_pow_div_set:
   "\<lbrakk> n < LENGTH('a) \<rbrakk> \<Longrightarrow>
    {x. x < (2 ^ n div 2 ^ m :: 'a::len word)}
       = of_nat ` {k. k < 2 ^ n div 2 ^ m}"
   apply (simp add: image_def)
   apply (safe dest!: word_less_two_pow_divD less_two_pow_divD
              intro!: word_less_two_pow_divI)
    apply (rule_tac x="unat x" in exI)
    apply (simp add: power_sub[symmetric])
    apply (subst unat_power_lower[symmetric, where 'a='a])
     apply simp
    apply (erule unat_mono)
   apply (subst word_unat_power)
   apply (rule of_nat_mono_maybe)
    apply (rule power_strict_increasing)
     apply simp
    apply simp
   apply assumption
   done
 
 lemma  word_less_power_trans2:
   fixes n :: "'a::len word"
   shows "\<lbrakk>n < 2 ^ (m - k); k \<le> m; m < LENGTH('a)\<rbrakk> \<Longrightarrow> n * 2 ^ k < 2 ^ m"
   by (subst field_simps, rule word_less_power_trans)
 
 (* shadows the slightly weaker Word.nth_ucast *)
 lemma nth_ucast:
   "(ucast (w::'a::len word)::'b::len word) !! n =
    (w !! n \<and> n < min LENGTH('a) LENGTH('b))"
   by transfer (simp add: bit_take_bit_iff ac_simps)
 
 lemma ucast_less:
   "LENGTH('b) < LENGTH('a) \<Longrightarrow>
    (ucast (x :: 'b :: len word) :: ('a :: len word)) < 2 ^ LENGTH('b)"
   by (meson Word.nth_ucast test_bit_conj_lt le_def upper_bits_unset_is_l2p)
 
 lemma ucast_range_less:
   "LENGTH('a :: len) < LENGTH('b :: len) \<Longrightarrow>
    range (ucast :: 'a word \<Rightarrow> 'b word) = {x. x < 2 ^ len_of TYPE ('a)}"
   apply safe
    apply (erule ucast_less)
   apply (simp add: image_def)
   apply (rule_tac x="ucast x" in exI)
   by word_eqI_solve
 
 lemma word_power_less_diff:
   "\<lbrakk>2 ^ n * q < (2::'a::len word) ^ m; q < 2 ^ (LENGTH('a) - n)\<rbrakk> \<Longrightarrow> q < 2 ^ (m - n)"
   apply (case_tac "m \<ge> LENGTH('a)")
    apply (simp add: power_overflow)
   apply (case_tac "n \<ge> LENGTH('a)")
    apply (simp add: power_overflow)
   apply (cases "n = 0")
    apply simp
   apply (subst word_less_nat_alt)
   apply (subst unat_power_lower)
    apply simp
   apply (rule nat_power_less_diff)
   apply (simp add: word_less_nat_alt)
   apply (subst (asm) iffD1 [OF unat_mult_lem])
    apply (simp add:nat_less_power_trans)
   apply simp
   done
 
 lemmas word_diff_ls'' = word_diff_ls [where xa=x and x=x for x]
 lemmas word_diff_ls' = word_diff_ls'' [simplified]
 
 lemmas word_l_diffs' = word_l_diffs [where xa=x and x=x for x]
 lemmas word_l_diffs = word_l_diffs' [simplified]
 
 lemma is_aligned_diff:
   fixes m :: "'a::len word"
   assumes alm: "is_aligned m s1"
   and     aln: "is_aligned n s2"
   and    s2wb: "s2 < LENGTH('a)"
   and      nm: "m \<in> {n .. n + (2 ^ s2 - 1)}"
   and    s1s2: "s1 \<le> s2"
   and     s10: "0 < s1" (* Probably can be folded into the proof \<dots> *)
 shows  "\<exists>q. m - n = of_nat q * 2 ^ s1 \<and> q < 2 ^ (s2 - s1)"
 proof -
   have rl: "\<And>m s. \<lbrakk> m < 2 ^ (LENGTH('a) - s); s < LENGTH('a) \<rbrakk> \<Longrightarrow> unat ((2::'a word) ^ s * of_nat m) = 2 ^ s * m"
   proof -
     fix m :: nat and  s
     assume m: "m < 2 ^ (LENGTH('a) - s)" and s: "s < LENGTH('a)"
     then have "unat ((of_nat m) :: 'a word) = m"
       apply (subst unat_of_nat)
       apply (subst mod_less)
        apply (erule order_less_le_trans)
        apply (rule power_increasing)
         apply simp_all
       done
 
     then show "?thesis m s" using s m
       apply (subst iffD1 [OF unat_mult_lem])
       apply (simp add: nat_less_power_trans)+
       done
   qed
   have s1wb: "s1 < LENGTH('a)" using s2wb s1s2 by simp
   from alm obtain mq where mmq: "m = 2 ^ s1 * of_nat mq" and mq: "mq < 2 ^ (LENGTH('a) - s1)"
     by (auto elim: is_alignedE simp: field_simps)
   from aln obtain nq where nnq: "n = 2 ^ s2 * of_nat nq" and nq: "nq < 2 ^ (LENGTH('a) - s2)"
     by (auto elim: is_alignedE simp: field_simps)
   from s1s2 obtain sq where sq: "s2 = s1 + sq" by (auto simp: le_iff_add)
 
   note us1 = rl [OF mq s1wb]
   note us2 = rl [OF nq s2wb]
 
   from nm have "n \<le> m" by clarsimp
   then have "(2::'a word) ^ s2 * of_nat nq \<le> 2 ^ s1 * of_nat mq" using nnq mmq by simp
   then have "2 ^ s2 * nq \<le> 2 ^ s1 * mq" using s1wb s2wb
     by (simp add: word_le_nat_alt us1 us2)
   then have nqmq: "2 ^ sq * nq \<le> mq" using sq by (simp add: power_add)
 
   have "m - n = 2 ^ s1 * of_nat mq - 2 ^ s2 * of_nat nq" using mmq nnq by simp
   also have "\<dots> = 2 ^ s1 * of_nat mq - 2 ^ s1 * 2 ^ sq * of_nat nq" using sq by (simp add: power_add)
   also have "\<dots> = 2 ^ s1 * (of_nat mq - 2 ^ sq * of_nat nq)" by (simp add: field_simps)
   also have "\<dots> = 2 ^ s1 * of_nat (mq - 2 ^ sq * nq)" using s1wb s2wb us1 us2 nqmq
     by (simp add:  word_unat_power)
   finally have mn: "m - n = of_nat (mq - 2 ^ sq * nq) * 2 ^ s1" by simp
   moreover
   from nm have "m - n \<le> 2 ^ s2 - 1"
     by - (rule word_diff_ls', (simp add: field_simps)+)
   then have "(2::'a word) ^ s1 * of_nat (mq - 2 ^ sq * nq) < 2 ^ s2" using mn s2wb by (simp add: field_simps)
   then have "of_nat (mq - 2 ^ sq * nq) < (2::'a word) ^ (s2 - s1)"
   proof (rule word_power_less_diff)
     have mm: "mq - 2 ^ sq * nq < 2 ^ (LENGTH('a) - s1)" using mq by simp
     moreover from s10 have "LENGTH('a) - s1 < LENGTH('a)"
       by (rule diff_less, simp)
     ultimately show "of_nat (mq - 2 ^ sq * nq) < (2::'a word) ^ (LENGTH('a) - s1)"
       using take_bit_nat_less_self_iff [of \<open>LENGTH('a)\<close> \<open>mq - 2 ^ sq * nq\<close>]
       apply (auto simp add: word_less_nat_alt not_le not_less)
       apply (metis take_bit_nat_eq_self_iff)
       done
   qed
   then have "mq - 2 ^ sq * nq < 2 ^ (s2 - s1)" using mq s2wb
     apply (simp add: word_less_nat_alt take_bit_eq_mod)
     apply (subst (asm) mod_less)
     apply auto
      apply (rule order_le_less_trans)
       apply (rule diff_le_self)
      apply (erule order_less_le_trans)
     apply simp
     done
   ultimately show ?thesis
     by auto
 qed
 
 lemma word_less_sub_1:
   "x < (y :: 'a :: len word) \<Longrightarrow> x \<le> y - 1"
   by (fact word_le_minus_one_leq)
 
 lemma word_sub_mono2:
   "\<lbrakk> a + b \<le> c + d; c \<le> a; b \<le> a + b; d \<le> c + d \<rbrakk>
     \<Longrightarrow> b \<le> (d :: 'a :: len word)"
   apply (drule(1) word_sub_mono)
     apply simp
    apply simp
   apply simp
   done
 
 lemma word_not_le:
   "(\<not> x \<le> (y :: 'a :: len word)) = (y < x)"
   by fastforce
 
 lemma word_subset_less:
   "\<lbrakk> {x .. x + r - 1} \<subseteq> {y .. y + s - 1};
      x \<le> x + r - 1; y \<le> y + (s :: 'a :: len word) - 1;
      s \<noteq> 0 \<rbrakk>
      \<Longrightarrow> r \<le> s"
   apply (frule subsetD[where c=x])
    apply simp
   apply (drule subsetD[where c="x + r - 1"])
    apply simp
   apply (clarsimp simp: add_diff_eq[symmetric])
   apply (drule(1) word_sub_mono2)
     apply (simp_all add: olen_add_eqv[symmetric])
   apply (erule word_le_minus_cancel)
   apply (rule ccontr)
   apply (simp add: word_not_le)
   done
 
 lemma uint_power_lower:
   "n < LENGTH('a) \<Longrightarrow> uint (2 ^ n :: 'a :: len word) = (2 ^ n :: int)"
   by (rule uint_2p_alt)
 
 lemma power_le_mono:
   "\<lbrakk>2 ^ n \<le> (2::'a::len word) ^ m; n < LENGTH('a); m < LENGTH('a)\<rbrakk>
    \<Longrightarrow> n \<le> m"
   apply (clarsimp simp add: le_less)
   apply safe
   apply (simp add: word_less_nat_alt)
   apply (simp only: uint_arith_simps(3))
   apply (drule uint_power_lower)+
   apply simp
   done
 
 lemma sublist_equal_part:
   "prefix xs ys \<Longrightarrow> take (length xs) ys = xs"
   by (clarsimp simp: prefix_def)
 
 lemma two_power_eq:
   "\<lbrakk>n < LENGTH('a); m < LENGTH('a)\<rbrakk>
    \<Longrightarrow> ((2::'a::len word) ^ n = 2 ^ m) = (n = m)"
   apply safe
   apply (rule order_antisym)
    apply (simp add: power_le_mono[where 'a='a])+
   done
 
 lemma prefix_length_less:
   "strict_prefix xs ys \<Longrightarrow> length xs < length ys"
   apply (clarsimp simp: strict_prefix_def)
   apply (frule prefix_length_le)
   apply (rule ccontr, simp)
   apply (clarsimp simp: prefix_def)
   done
 
 lemmas take_less = take_strict_prefix
 
 lemma not_prefix_longer:
   "\<lbrakk> length xs > length ys \<rbrakk> \<Longrightarrow> \<not> prefix xs ys"
   by (clarsimp dest!: prefix_length_le)
 
 lemma of_bl_length:
   "length xs < LENGTH('a) \<Longrightarrow> of_bl xs < (2 :: 'a::len word) ^ length xs"
   by (simp add: of_bl_length_less)
 
 lemma unat_of_nat_eq:
   "x < 2 ^ LENGTH('a) \<Longrightarrow> unat (of_nat x ::'a::len word) = x"
   by (rule unat_of_nat_len)
 
 lemma unat_eq_of_nat:
   "n < 2 ^ LENGTH('a) \<Longrightarrow> (unat (x :: 'a::len word) = n) = (x = of_nat n)"
   by transfer
     (auto simp add: take_bit_of_nat nat_eq_iff take_bit_nat_eq_self_iff intro: sym)
 
 lemma unat_less_helper:
   "x < of_nat n \<Longrightarrow> unat x < n"
   apply (simp add: word_less_nat_alt)
   apply (erule order_less_le_trans)
   apply (simp add: take_bit_eq_mod)
   done
 
 lemma nat_uint_less_helper:
   "nat (uint y) = z \<Longrightarrow> x < y \<Longrightarrow> nat (uint x) < z"
   apply (erule subst)
   apply (subst unat_eq_nat_uint [symmetric])
   apply (subst unat_eq_nat_uint [symmetric])
   by (simp add: unat_mono)
 
 lemma of_nat_0:
   "\<lbrakk>of_nat n = (0::'a::len word); n < 2 ^ LENGTH('a)\<rbrakk> \<Longrightarrow> n = 0"
   by transfer (simp add: take_bit_eq_mod)
 
 lemma word_leq_le_minus_one:
   "\<lbrakk> x \<le> y; x \<noteq> 0 \<rbrakk> \<Longrightarrow> x - 1 < (y :: 'a :: len word)"
   apply (simp add: word_less_nat_alt word_le_nat_alt)
   apply (subst unat_minus_one)
    apply assumption
   apply (cases "unat x")
    apply (simp add: unat_eq_zero)
   apply arith
   done
 
 lemma of_nat_inj:
   "\<lbrakk>x < 2 ^ LENGTH('a); y < 2 ^ LENGTH('a)\<rbrakk> \<Longrightarrow>
    (of_nat x = (of_nat y :: 'a :: len word)) = (x = y)"
   by (simp add: word_unat.norm_eq_iff [symmetric])
 
 lemma map_prefixI:
   "prefix xs ys \<Longrightarrow> prefix (map f xs) (map f ys)"
   by (clarsimp simp: prefix_def)
 
 lemma if_Some_None_eq_None:
   "((if P then Some v else None) = None) = (\<not> P)"
   by simp
 
 lemma CollectPairFalse [iff]:
   "{(a,b). False} = {}"
   by (simp add: split_def)
 
 lemma if_conj_dist:
   "((if b then w else x) \<and> (if b then y else z) \<and> X) =
   ((if b then w \<and> y else x \<and> z) \<and> X)"
   by simp
 
 lemma if_P_True1:
   "Q \<Longrightarrow> (if P then True else Q)"
   by simp
 
 lemma if_P_True2:
   "Q \<Longrightarrow> (if P then Q else True)"
   by simp
 
 lemma list_all2_induct [consumes 1, case_names Nil Cons]:
   assumes lall: "list_all2 Q xs ys"
   and     nilr: "P [] []"
   and    consr: "\<And>x xs y ys. \<lbrakk>list_all2 Q xs ys; Q x y; P xs ys\<rbrakk> \<Longrightarrow> P (x # xs) (y # ys)"
   shows  "P xs ys"
   using lall
 proof (induct rule: list_induct2 [OF list_all2_lengthD [OF lall]])
   case 1 then show ?case by auto fact+
 next
   case (2 x xs y ys)
 
   show ?case
   proof (rule consr)
     from "2.prems" show "list_all2 Q xs ys" and "Q x y" by simp_all
     then show "P xs ys" by (intro "2.hyps")
   qed
 qed
 
 lemma list_all2_induct_suffixeq [consumes 1, case_names Nil Cons]:
   assumes lall: "list_all2 Q as bs"
   and     nilr: "P [] []"
   and    consr: "\<And>x xs y ys.
   \<lbrakk>list_all2 Q xs ys; Q x y; P xs ys; suffix (x # xs) as; suffix (y # ys) bs\<rbrakk>
   \<Longrightarrow> P (x # xs) (y # ys)"
   shows  "P as bs"
 proof -
   define as' where "as' == as"
   define bs' where "bs' == bs"
 
   have "suffix as as' \<and> suffix bs bs'" unfolding as'_def bs'_def by simp
   then show ?thesis using lall
   proof (induct rule: list_induct2 [OF list_all2_lengthD [OF lall]])
     case 1 show ?case by fact
   next
     case (2 x xs y ys)
 
     show ?case
     proof (rule consr)
       from "2.prems" show "list_all2 Q xs ys" and "Q x y" by simp_all
       then show "P xs ys" using "2.hyps" "2.prems" by (auto dest: suffix_ConsD)
       from "2.prems" show "suffix (x # xs) as" and "suffix (y # ys) bs"
       by (auto simp: as'_def bs'_def)
     qed
   qed
 qed
 
 lemma upto_enum_step_shift:
   "\<lbrakk> is_aligned p n \<rbrakk> \<Longrightarrow>
   ([p , p + 2 ^ m .e. p + 2 ^ n - 1])
       = map ((+) p) [0, 2 ^ m .e. 2 ^ n - 1]"
   apply (erule is_aligned_get_word_bits)
    prefer 2
    apply (simp add: map_idI)
   apply (clarsimp simp: upto_enum_step_def)
   apply (frule is_aligned_no_overflow)
   apply (simp add: linorder_not_le [symmetric])
   done
 
 lemma upto_enum_step_shift_red:
   "\<lbrakk> is_aligned p sz; sz < LENGTH('a); us \<le> sz \<rbrakk>
      \<Longrightarrow> [p :: 'a :: len word, p + 2 ^ us .e. p + 2 ^ sz - 1]
           = map (\<lambda>x. p + of_nat x * 2 ^ us) [0 ..< 2 ^ (sz - us)]"
   apply (subst upto_enum_step_shift, assumption)
   apply (simp add: upto_enum_step_red)
   done
 
 lemma div_to_mult_word_lt:
   "\<lbrakk> (x :: 'a :: len word) \<le> y div z \<rbrakk> \<Longrightarrow> x * z \<le> y"
   apply (cases "z = 0")
    apply simp
   apply (simp add: word_neq_0_conv)
   apply (rule order_trans)
    apply (erule(1) word_mult_le_mono1)
    apply (simp add: unat_div)
    apply (rule order_le_less_trans [OF div_mult_le])
    apply simp
   apply (rule word_div_mult_le)
   done
 
 lemma upto_enum_step_subset:
   "set [x, y .e. z] \<subseteq> {x .. z}"
   apply (clarsimp simp: upto_enum_step_def linorder_not_less)
   apply (drule div_to_mult_word_lt)
   apply (rule conjI)
    apply (erule word_random[rotated])
    apply simp
   apply (rule order_trans)
    apply (erule word_plus_mono_right)
    apply simp
   apply simp
   done
 
 lemma shiftr_less_t2n':
   "\<lbrakk> x && mask (n + m) = x; m < LENGTH('a) \<rbrakk> \<Longrightarrow> x >> n < 2 ^ m" for x :: "'a :: len word"
   apply (simp add: word_size mask_eq_iff_w2p[symmetric])
   apply word_eqI
   apply (erule_tac x="na + n" in allE)
   apply fastforce
   done
 
 lemma shiftr_less_t2n:
   "x < 2 ^ (n + m) \<Longrightarrow> x >> n < 2 ^ m" for x :: "'a :: len word"
   apply (rule shiftr_less_t2n')
    apply (erule less_mask_eq)
   apply (rule ccontr)
   apply (simp add: not_less)
   apply (subst (asm) p2_eq_0[symmetric])
   apply (simp add: power_add)
   done
 
 lemma shiftr_eq_0:
   "n \<ge> LENGTH('a) \<Longrightarrow> ((w::'a::len word) >> n) = 0"
   apply (cut_tac shiftr_less_t2n'[of w n 0], simp)
    apply (simp add: mask_eq_iff)
   apply (simp add: lt2p_lem)
   apply simp
   done
 
 lemma shiftr_not_mask_0:
   "n+m \<ge> LENGTH('a :: len) \<Longrightarrow> ((w::'a::len word) >> n) && ~~ (mask m) = 0"
   apply (simp add: and_not_mask shiftr_less_t2n shiftr_shiftr)
   apply (subgoal_tac "w >> n + m = 0", simp)
   apply (simp add: le_mask_iff[symmetric] mask_eq_decr_exp le_def)
   apply (subst (asm) p2_gt_0[symmetric])
   apply (simp add: power_add not_less)
   done
 
 lemma shiftl_less_t2n:
   fixes x :: "'a :: len word"
   shows "\<lbrakk> x < (2 ^ (m - n)); m < LENGTH('a) \<rbrakk> \<Longrightarrow> (x << n) < 2 ^ m"
   apply (simp add: word_size mask_eq_iff_w2p[symmetric])
   apply word_eqI
   apply (erule_tac x="na - n" in allE)
   apply auto
   done
 
 lemma shiftl_less_t2n':
   "(x::'a::len word) < 2 ^ m \<Longrightarrow> m+n < LENGTH('a) \<Longrightarrow> x << n < 2 ^ (m + n)"
   by (rule shiftl_less_t2n) simp_all
 
 lemma ucast_ucast_mask:
   "(ucast :: 'a :: len word \<Rightarrow> 'b :: len word) (ucast x) = x && mask (len_of TYPE ('a))"
   by word_eqI
 
 lemma ucast_ucast_len:
   "\<lbrakk> x < 2 ^ LENGTH('b) \<rbrakk> \<Longrightarrow> ucast (ucast x::'b::len word) = (x::'a::len word)"
   apply (subst ucast_ucast_mask)
   apply (erule less_mask_eq)
   done
 
 lemma ucast_ucast_id:
   "LENGTH('a) < LENGTH('b) \<Longrightarrow> ucast (ucast (x::'a::len word)::'b::len word) = x"
   by (auto intro: ucast_up_ucast_id simp: is_up_def source_size_def target_size_def word_size)
 
 lemma unat_ucast:
   "unat (ucast x :: ('a :: len) word) = unat x mod 2 ^ (LENGTH('a))"
 proof -
   have \<open>2 ^ LENGTH('a) = nat (2 ^ LENGTH('a))\<close>
     by simp
   moreover have \<open>unat (UCAST('b \<rightarrow> 'a) x) = unat x mod nat (2 ^ LENGTH('a))\<close>
     by transfer (simp flip: nat_mod_distrib take_bit_eq_mod)
   ultimately show ?thesis
     by (simp only:)
 qed
 
 lemma ucast_less_ucast:
   "LENGTH('a) \<le> LENGTH('b) \<Longrightarrow>
    (ucast x < ((ucast (y :: 'a::len word)) :: 'b::len word)) = (x < y)"
   apply (simp add: word_less_nat_alt unat_ucast)
   apply (subst mod_less)
    apply(rule less_le_trans[OF unat_lt2p], simp)
   apply (subst mod_less)
    apply(rule less_le_trans[OF unat_lt2p], simp)
   apply simp
   done
 
 \<comment> \<open>This weaker version was previously called @{text ucast_less_ucast}. We retain it to
     support existing proofs.\<close>
 lemmas ucast_less_ucast_weak = ucast_less_ucast[OF order.strict_implies_order]
 
 lemma sints_subset:
   "m \<le> n \<Longrightarrow> sints m \<subseteq> sints n"
   apply (simp add: sints_num)
   apply clarsimp
   apply (rule conjI)
    apply (erule order_trans[rotated])
    apply simp
   apply (erule order_less_le_trans)
   apply simp
   done
 
 lemma up_scast_inj:
       "\<lbrakk> scast x = (scast y :: 'b :: len word); size x \<le> LENGTH('b) \<rbrakk>
          \<Longrightarrow> x = y"
   apply (unfold scast_eq)
   apply (subst(asm) word_sint.Abs_inject)
     apply (erule subsetD [OF sints_subset])
     apply (simp add: word_size)
    apply (erule subsetD [OF sints_subset])
    apply (simp add: word_size)
   apply simp
   done
 
 lemma up_scast_inj_eq:
   "LENGTH('a) \<le> len_of TYPE ('b) \<Longrightarrow>
   (scast x = (scast y::'b::len word)) = (x = (y::'a::len word))"
   by (fastforce dest: up_scast_inj simp: word_size)
 
 lemma nth_bounded:
   "\<lbrakk>(x :: 'a :: len word) !! n; x < 2 ^ m; m \<le> len_of TYPE ('a)\<rbrakk> \<Longrightarrow> n < m"
   apply (frule test_bit_size)
   apply (clarsimp simp: test_bit_bl word_size)
   apply (simp add: rev_nth)
   apply (subst(asm) is_aligned_add_conv[OF is_aligned_0',
                                         simplified add_0_left, rotated])
    apply assumption+
   apply (simp only: to_bl_0)
   apply (simp add: nth_append split: if_split_asm)
   done
 
 lemma is_aligned_add_or:
   "\<lbrakk>is_aligned p n; d < 2 ^ n\<rbrakk> \<Longrightarrow> p + d = p || d"
   by (rule word_plus_and_or_coroll, word_eqI) blast
 
 lemma two_power_increasing:
   "\<lbrakk> n \<le> m; m < LENGTH('a) \<rbrakk> \<Longrightarrow> (2 :: 'a :: len word) ^ n \<le> 2 ^ m"
   by (simp add: word_le_nat_alt)
 
 lemma is_aligned_add_less_t2n:
   "\<lbrakk>is_aligned (p::'a::len word) n; d < 2^n; n \<le> m; p < 2^m\<rbrakk> \<Longrightarrow> p + d < 2^m"
   apply (case_tac "m < LENGTH('a)")
    apply (subst mask_eq_iff_w2p[symmetric])
     apply (simp add: word_size)
    apply (simp add: is_aligned_add_or word_ao_dist less_mask_eq)
    apply (subst less_mask_eq)
     apply (erule order_less_le_trans)
     apply (erule(1) two_power_increasing)
    apply simp
   apply (simp add: power_overflow)
   done
 
 
 lemma aligned_offset_non_zero:
   "\<lbrakk> is_aligned x n; y < 2 ^ n; x \<noteq> 0 \<rbrakk> \<Longrightarrow> x + y \<noteq> 0"
   apply (cases "y = 0")
    apply simp
   apply (subst word_neq_0_conv)
   apply (subst gt0_iff_gem1)
   apply (erule is_aligned_get_word_bits)
    apply (subst field_simps[symmetric], subst plus_le_left_cancel_nowrap)
      apply (rule is_aligned_no_wrap')
       apply simp
      apply (rule word_leq_le_minus_one)
       apply simp
      apply assumption
     apply (erule (1) is_aligned_no_wrap')
    apply (simp add: gt0_iff_gem1 [symmetric] word_neq_0_conv)
   apply simp
   done
 
 lemmas mask_inner_mask = mask_eqs(1)
 
 lemma mask_add_aligned:
   "is_aligned p n \<Longrightarrow> (p + q) && mask n = q && mask n"
   apply (simp add: is_aligned_mask)
   apply (subst mask_inner_mask [symmetric])
   apply simp
   done
 
 lemma take_prefix:
   "(take (length xs) ys = xs) = prefix xs ys"
 proof (induct xs arbitrary: ys)
   case Nil then show ?case by simp
 next
   case Cons then show ?case by (cases ys) auto
 qed
 
 lemma cart_singleton_empty:
   "(S \<times> {e} = {}) = (S = {})"
   by blast
 
 lemma word_div_1:
   "(n :: 'a :: len word) div 1 = n"
   by (simp add: word_div_def)
 
 lemma word_minus_one_le:
   "-1 \<le> (x :: 'a :: len word) = (x = -1)"
   apply (insert word_n1_ge[where y=x])
   apply safe
   apply (erule(1) order_antisym)
   done
 
 lemma mask_out_sub_mask:
   "(x && ~~ (mask n)) = x - (x && (mask n))"
   by (simp add: field_simps word_plus_and_or_coroll2)
 
 lemma is_aligned_addD1:
   assumes al1: "is_aligned (x + y) n"
   and     al2: "is_aligned (x::'a::len word) n"
   shows "is_aligned y n"
   using al2
 proof (rule is_aligned_get_word_bits)
   assume "x = 0" then show ?thesis using al1 by simp
 next
   assume nv: "n < LENGTH('a)"
   from al1 obtain q1
     where xy: "x + y = 2 ^ n * of_nat q1" and "q1 < 2 ^ (LENGTH('a) - n)"
     by (rule is_alignedE)
   moreover from al2 obtain q2
     where x: "x = 2 ^ n * of_nat q2" and "q2 < 2 ^ (LENGTH('a) - n)"
     by (rule is_alignedE)
   ultimately have "y = 2 ^ n * (of_nat q1 - of_nat q2)"
     by (simp add: field_simps)
   then show ?thesis using nv by (simp add: is_aligned_mult_triv1)
 qed
 
 lemmas is_aligned_addD2 =
        is_aligned_addD1[OF subst[OF add.commute,
                                  of "%x. is_aligned x n" for n]]
 
 lemma is_aligned_add:
   "\<lbrakk>is_aligned p n; is_aligned q n\<rbrakk> \<Longrightarrow> is_aligned (p + q) n"
   by (simp add: is_aligned_mask mask_add_aligned)
 
 lemma word_le_add:
   fixes x :: "'a :: len word"
   shows "x \<le> y \<Longrightarrow> \<exists>n. y = x + of_nat n"
   by (rule exI [where x = "unat (y - x)"]) simp
 
 lemma word_plus_mcs_4':
   fixes x :: "'a :: len word"
   shows "\<lbrakk>x + v \<le> x + w; x \<le> x + v\<rbrakk> \<Longrightarrow> v \<le> w"
   apply (rule word_plus_mcs_4)
    apply (simp add: add.commute)
   apply (simp add: add.commute)
   done
 
 lemma shiftl_mask_is_0[simp]:
   "(x << n) && mask n = 0"
   apply (rule iffD1 [OF is_aligned_mask])
   apply (rule is_aligned_shiftl_self)
   done
 
 definition
   sum_map :: "('a \<Rightarrow> 'b) \<Rightarrow> ('c \<Rightarrow> 'd) \<Rightarrow> 'a + 'c \<Rightarrow> 'b + 'd" where
  "sum_map f g x \<equiv> case x of Inl v \<Rightarrow> Inl (f v) | Inr v' \<Rightarrow> Inr (g v')"
 
 lemma sum_map_simps[simp]:
   "sum_map f g (Inl v) = Inl (f v)"
   "sum_map f g (Inr w) = Inr (g w)"
   by (simp add: sum_map_def)+
 
 lemma if_and_helper:
   "(If x v v') && v'' = If x (v && v'') (v' && v'')"
   by (rule if_distrib)
 
 lemma unat_Suc2:
   fixes n :: "'a :: len word"
   shows
   "n \<noteq> -1 \<Longrightarrow> unat (n + 1) = Suc (unat n)"
   apply (subst add.commute, rule unatSuc)
   apply (subst eq_diff_eq[symmetric], simp add: minus_equation_iff)
   done
 
 lemmas word_unat_Rep_inject1 = word_unat.Rep_inject[where y=1]
 lemmas unat_eq_1 = unat_eq_0 word_unat_Rep_inject1[simplified]
 
 
 lemma rshift_sub_mask_eq:
   "(a >> (size a - b)) && mask b = a >> (size a - b)"
   using shiftl_shiftr2[where a=a and b=0 and c="size a - b"]
   apply (cases "b < size a")
    apply simp
   apply (simp add: linorder_not_less mask_eq_decr_exp word_size
                    p2_eq_0[THEN iffD2])
   done
 
 lemma shiftl_shiftr3:
   "b \<le> c \<Longrightarrow> a << b >> c = (a >> c - b) && mask (size a - c)"
   apply (cases "b = c")
    apply (simp add: shiftl_shiftr1)
   apply (simp add: shiftl_shiftr2)
   done
 
 lemma and_mask_shiftr_comm:
-  "m\<le>size w \<Longrightarrow> (w && mask m) >> n = (w >> n) && mask (m-n)"
+  "m \<le> size w \<Longrightarrow> (w && mask m) >> n = (w >> n) && mask (m-n)"
   by (simp add: and_mask shiftr_shiftr) (simp add: word_size shiftl_shiftr3)
 
 lemma and_mask_shiftl_comm:
   "m+n \<le> size w \<Longrightarrow> (w && mask m) << n = (w << n) && mask (m+n)"
   by (simp add: and_mask word_size shiftl_shiftl) (simp add: shiftl_shiftr1)
 
 lemma le_mask_shiftl_le_mask: "s = m + n \<Longrightarrow> x \<le> mask n \<Longrightarrow> x << m \<le> mask s"
   for x :: \<open>'a::len word\<close>
   by (simp add: le_mask_iff shiftl_shiftr3)
 
 lemma and_not_mask_twice:
   "(w && ~~ (mask n)) && ~~ (mask m) = w && ~~ (mask (max m n))"
   apply (simp add: and_not_mask)
   apply (case_tac "n<m";
          simp add: shiftl_shiftr2 shiftl_shiftr1 not_less max_def shiftr_shiftr shiftl_shiftl)
    apply (cut_tac and_mask_shiftr_comm [where w=w and m="size w" and n=m, simplified,symmetric])
    apply (simp add: word_size mask_eq_decr_exp)
   apply (cut_tac and_mask_shiftr_comm [where w=w and m="size w" and n=n, simplified,symmetric])
   apply (simp add: word_size mask_eq_decr_exp)
   done
 
 lemma word_less_cases:
   "x < y \<Longrightarrow> x = y - 1 \<or> x < y - (1 ::'a::len word)"
   apply (drule word_less_sub_1)
   apply (drule order_le_imp_less_or_eq)
   apply auto
   done
 
 lemma eq_eqI:
   "a = b \<Longrightarrow> (a = x) = (b = x)"
   by simp
 
 lemma mask_and_mask:
   "mask a && mask b = mask (min a b)"
   by word_eqI
 
 lemma mask_eq_0_eq_x:
   "(x && w = 0) = (x && ~~ w = x)"
   using word_plus_and_or_coroll2[where x=x and w=w]
   by auto
 
 lemma mask_eq_x_eq_0:
   "(x && w = x) = (x && ~~ w = 0)"
   using word_plus_and_or_coroll2[where x=x and w=w]
   by auto
 
 definition
   "limited_and (x :: 'a :: len word) y = (x && y = x)"
 
 lemma limited_and_eq_0:
   "\<lbrakk> limited_and x z; y && ~~ z = y \<rbrakk> \<Longrightarrow> x && y = 0"
   unfolding limited_and_def
   apply (subst arg_cong2[where f="(&&)"])
     apply (erule sym)+
   apply (simp(no_asm) add: word_bw_assocs word_bw_comms word_bw_lcs)
   done
 
 lemma limited_and_eq_id:
   "\<lbrakk> limited_and x z; y && z = z \<rbrakk> \<Longrightarrow> x && y = x"
   unfolding limited_and_def
   by (erule subst, fastforce simp: word_bw_lcs word_bw_assocs word_bw_comms)
 
 lemma lshift_limited_and:
   "limited_and x z \<Longrightarrow> limited_and (x << n) (z << n)"
   unfolding limited_and_def
   by (simp add: shiftl_over_and_dist[symmetric])
 
 lemma rshift_limited_and:
   "limited_and x z \<Longrightarrow> limited_and (x >> n) (z >> n)"
   unfolding limited_and_def
   by (simp add: shiftr_over_and_dist[symmetric])
 
 lemmas limited_and_simps1 = limited_and_eq_0 limited_and_eq_id
 
 lemmas is_aligned_limited_and
     = is_aligned_neg_mask_eq[unfolded mask_eq_decr_exp, folded limited_and_def]
 
 lemma compl_of_1: "~~ 1 = (-2 :: 'a :: len word)"
   by (fact not_one)
 
 lemmas limited_and_simps = limited_and_simps1
        limited_and_simps1[OF is_aligned_limited_and]
        limited_and_simps1[OF lshift_limited_and]
        limited_and_simps1[OF rshift_limited_and]
        limited_and_simps1[OF rshift_limited_and, OF is_aligned_limited_and]
        compl_of_1 shiftl_shiftr1[unfolded word_size mask_eq_decr_exp]
        shiftl_shiftr2[unfolded word_size mask_eq_decr_exp]
 
 lemma split_word_eq_on_mask:
   "(x = y) = (x && m = y && m \<and> x && ~~ m = y && ~~ m)"
   by safe word_eqI_solve
 
 lemma map2_Cons_2_3:
   "(map2 f xs (y # ys) = (z # zs)) = (\<exists>x xs'. xs = x # xs' \<and> f x y = z \<and> map2 f xs' ys = zs)"
   by (case_tac xs, simp_all)
 
 lemma map2_xor_replicate_False:
   "map2 (\<lambda>x y. x \<longleftrightarrow> \<not> y) xs (replicate n False) = take n xs"
   apply (induct xs arbitrary: n, simp)
   apply (case_tac n; simp)
   done
 
 lemma word_and_1_shiftl:
   "x && (1 << n) = (if x !! n then (1 << n) else 0)" for x :: "'a :: len word"
   by word_eqI_solve
 
 lemmas word_and_1_shiftls'
     = word_and_1_shiftl[where n=0]
       word_and_1_shiftl[where n=1]
       word_and_1_shiftl[where n=2]
 
 lemmas word_and_1_shiftls = word_and_1_shiftls' [simplified]
 
 lemma word_and_mask_shiftl:
   "x && (mask n << m) = ((x >> m) && mask n) << m"
   by word_eqI_solve
 
 lemma plus_Collect_helper:
   "(+) x ` {xa. P (xa :: 'a :: len word)} = {xa. P (xa - x)}"
   by (fastforce simp add: image_def)
 
 lemma plus_Collect_helper2:
   "(+) (- x) ` {xa. P (xa :: 'a :: len word)} = {xa. P (x + xa)}"
   using plus_Collect_helper [of "- x" P] by (simp add: ac_simps)
 
 lemma word_FF_is_mask:
   "0xFF = (mask 8 :: 'a::len word)"
   by (simp add: mask_eq_decr_exp)
 
 lemma word_1FF_is_mask:
   "0x1FF = (mask 9 :: 'a::len word)"
   by (simp add: mask_eq_decr_exp)
 
 lemma ucast_of_nat_small:
   "x < 2 ^ LENGTH('a) \<Longrightarrow> ucast (of_nat x :: 'a :: len word) = (of_nat x :: 'b :: len word)"
   apply (rule sym, subst word_unat.inverse_norm)
   apply (simp add: ucast_eq of_nat_nat[symmetric] take_bit_eq_mod)
   done
 
 lemma word_le_make_less:
   fixes x :: "'a :: len word"
   shows "y \<noteq> -1 \<Longrightarrow> (x \<le> y) = (x < (y + 1))"
   apply safe
   apply (erule plus_one_helper2)
   apply (simp add: eq_diff_eq[symmetric])
   done
 
 lemmas finite_word = finite [where 'a="'a::len word"]
 
 lemma word_to_1_set:
   "{0 ..< (1 :: 'a :: len word)} = {0}"
   by fastforce
 
 lemma range_subset_eq2:
   "{a :: 'a :: len word .. b} \<noteq> {} \<Longrightarrow> ({a .. b} \<subseteq> {c .. d}) = (c \<le> a \<and> b \<le> d)"
   by simp
 
 lemma word_leq_minus_one_le:
   fixes x :: "'a::len word"
   shows "\<lbrakk>y \<noteq> 0; x \<le> y - 1 \<rbrakk> \<Longrightarrow> x < y"
   using le_m1_iff_lt word_neq_0_conv by blast
 
 lemma word_count_from_top:
   "n \<noteq> 0 \<Longrightarrow> {0 ..< n :: 'a :: len word} = {0 ..< n - 1} \<union> {n - 1}"
   apply (rule set_eqI, rule iffI)
    apply simp
    apply (drule word_le_minus_one_leq)
    apply (rule disjCI)
    apply simp
   apply simp
   apply (erule word_leq_minus_one_le)
   apply fastforce
   done
 
 lemma word_minus_one_le_leq:
   "\<lbrakk> x - 1 < y \<rbrakk> \<Longrightarrow> x \<le> (y :: 'a :: len word)"
   apply (cases "x = 0")
    apply simp
   apply (simp add: word_less_nat_alt word_le_nat_alt)
   apply (subst(asm) unat_minus_one)
    apply (simp add: word_less_nat_alt)
   apply (cases "unat x")
    apply (simp add: unat_eq_zero)
   apply arith
   done
 
 lemma mod_mod_power:
   fixes k :: nat
   shows "k mod 2 ^ m mod 2 ^ n = k mod 2 ^ (min m n)"
 proof (cases "m \<le> n")
   case True
 
   then have "k mod 2 ^ m mod 2 ^ n = k mod 2 ^ m"
     apply -
     apply (subst mod_less [where n = "2 ^ n"])
     apply (rule order_less_le_trans [OF mod_less_divisor])
     apply simp+
     done
   also have "\<dots> = k mod  2 ^ (min m n)" using True by simp
   finally show ?thesis .
 next
   case False
   then have "n < m" by simp
   then obtain d where md: "m = n + d"
     by (auto dest: less_imp_add_positive)
   then have "k mod 2 ^ m = 2 ^ n * (k div 2 ^ n mod 2 ^ d) + k mod 2 ^ n"
     by (simp add: mod_mult2_eq power_add)
   then have "k mod 2 ^ m mod 2 ^ n = k mod 2 ^ n"
     by (simp add: mod_add_left_eq)
   then show ?thesis using False
     by simp
 qed
 
 lemma word_div_less:
   "m < n \<Longrightarrow> m div n = 0" for m :: "'a :: len word"
   by (simp add: unat_mono word_arith_nat_defs(6))
 
 lemma word_must_wrap:
   "\<lbrakk> x \<le> n - 1; n \<le> x \<rbrakk> \<Longrightarrow> n = (0 :: 'a :: len word)"
   using dual_order.trans sub_wrap word_less_1 by blast
 
 lemma range_subset_card:
   "\<lbrakk> {a :: 'a :: len word .. b} \<subseteq> {c .. d}; b \<ge> a \<rbrakk> \<Longrightarrow> d \<ge> c \<and> d - c \<ge> b - a"
   using word_sub_le word_sub_mono by fastforce
 
 lemma less_1_simp:
   "n - 1 < m = (n \<le> (m :: 'a :: len word) \<and> n \<noteq> 0)"
   by unat_arith
 
 lemma alignUp_div_helper:
   fixes a :: "'a::len word"
   assumes kv: "k < 2 ^ (LENGTH('a) - n)"
   and     xk: "x = 2 ^ n * of_nat k"
   and    le: "a \<le> x"
   and    sz: "n < LENGTH('a)"
   and   anz: "a mod 2 ^ n \<noteq> 0"
   shows "a div 2 ^ n < of_nat k"
 proof -
   have kn: "unat (of_nat k :: 'a word) * unat ((2::'a word) ^ n) < 2 ^ LENGTH('a)"
     using xk kv sz
     apply (subst unat_of_nat_eq)
      apply (erule order_less_le_trans)
      apply simp
     apply (subst unat_power_lower, simp)
     apply (subst mult.commute)
     apply (rule nat_less_power_trans)
      apply simp
     apply simp
     done
 
   have "unat a div 2 ^ n * 2 ^ n \<noteq> unat a"
   proof -
     have "unat a = unat a div 2 ^ n * 2 ^ n + unat a mod 2 ^ n"
       by (simp add: div_mult_mod_eq)
     also have "\<dots> \<noteq> unat a div 2 ^ n * 2 ^ n" using sz anz
       by (simp add: unat_arith_simps)
     finally show ?thesis ..
   qed
 
   then have "a div 2 ^ n * 2 ^ n < a" using sz anz
     apply (subst word_less_nat_alt)
     apply (subst unat_word_ariths)
     apply (subst unat_div)
     apply simp
     apply (rule order_le_less_trans [OF mod_less_eq_dividend])
     apply (erule order_le_neq_trans [OF div_mult_le])
     done
 
   also from xk le have "\<dots> \<le> of_nat k * 2 ^ n" by (simp add: field_simps)
   finally show ?thesis using sz kv
     apply -
     apply (erule word_mult_less_dest [OF _ _ kn])
     apply (simp add: unat_div)
     apply (rule order_le_less_trans [OF div_mult_le])
     apply (rule unat_lt2p)
     done
 qed
 
 lemma nat_mod_power_lem:
   fixes a :: nat
   shows "1 < a \<Longrightarrow> a ^ n mod a ^ m = (if m \<le> n then 0 else a ^ n)"
   apply (clarsimp)
   apply (clarsimp simp add: le_iff_add power_add)
   done
 
 lemma power_mod_div:
   fixes x :: "nat"
   shows "x mod 2 ^ n div 2 ^ m = x div 2 ^ m mod 2 ^ (n - m)" (is "?LHS = ?RHS")
 proof (cases "n \<le> m")
   case True
   then have "?LHS = 0"
     apply -
     apply (rule div_less)
     apply (rule order_less_le_trans [OF mod_less_divisor]; simp)
     done
   also have "\<dots> = ?RHS" using True
     by simp
   finally show ?thesis .
 next
   case False
   then have lt: "m < n" by simp
   then obtain q where nv: "n = m + q" and "0 < q"
     by (auto dest: less_imp_Suc_add)
 
   then have "x mod 2 ^ n = 2 ^ m * (x div 2 ^ m mod 2 ^ q) + x mod 2 ^ m"
     by (simp add: power_add mod_mult2_eq)
 
   then have "?LHS = x div 2 ^ m mod 2 ^ q"
     by (simp add: div_add1_eq)
 
   also have "\<dots> = ?RHS" using nv
     by simp
 
   finally show ?thesis .
 qed
 
 lemma word_power_mod_div:
   fixes x :: "'a::len word"
   shows "\<lbrakk> n < LENGTH('a); m < LENGTH('a)\<rbrakk>
   \<Longrightarrow> x mod 2 ^ n div 2 ^ m = x div 2 ^ m mod 2 ^ (n - m)"
   apply (simp add: word_arith_nat_div unat_mod power_mod_div)
   apply (subst unat_arith_simps(3))
   apply (subst unat_mod)
   apply (subst unat_of_nat)+
   apply (simp add: mod_mod_power min.commute)
   done
 
 lemma word_range_minus_1':
   fixes a :: "'a :: len word"
   shows "a \<noteq> 0 \<Longrightarrow> {a - 1<..b} = {a..b}"
   by (simp add: greaterThanAtMost_def atLeastAtMost_def greaterThan_def atLeast_def less_1_simp)
 
 lemma word_range_minus_1:
   fixes a :: "'a :: len word"
   shows "b \<noteq> 0 \<Longrightarrow> {a..b - 1} = {a..<b}"
   apply (simp add: atLeastLessThan_def atLeastAtMost_def atMost_def lessThan_def)
   apply (rule arg_cong [where f = "\<lambda>x. {a..} \<inter> x"])
   apply rule
    apply clarsimp
    apply (erule contrapos_pp)
    apply (simp add: linorder_not_less linorder_not_le word_must_wrap)
   apply (clarsimp)
   apply (drule word_le_minus_one_leq)
   apply (auto simp: word_less_sub_1)
   done
 
 lemma ucast_nat_def:
   "of_nat (unat x) = (ucast :: 'a :: len word \<Rightarrow> 'b :: len word) x"
   by transfer simp
 
 lemmas if_fun_split = if_apply_def2
 
 lemma i_hate_words_helper:
   "i \<le> (j - k :: nat) \<Longrightarrow> i \<le> j"
   by simp
 
 lemma i_hate_words:
   "unat (a :: 'a word) \<le> unat (b :: 'a :: len word) - Suc 0
     \<Longrightarrow> a \<noteq> -1"
   apply (frule i_hate_words_helper)
   apply (subst(asm) word_le_nat_alt[symmetric])
   apply (clarsimp simp only: word_minus_one_le)
   apply (simp only: linorder_not_less[symmetric])
   apply (erule notE)
   apply (rule diff_Suc_less)
   apply (subst neq0_conv[symmetric])
   apply (subst unat_eq_0)
   apply (rule notI, drule arg_cong[where f="(+) 1"])
   apply simp
   done
 
 lemma overflow_plus_one_self:
   "(1 + p \<le> p) = (p = (-1 :: 'a :: len word))"
   apply rule
   apply (rule ccontr)
    apply (drule plus_one_helper2)
    apply (rule notI)
    apply (drule arg_cong[where f="\<lambda>x. x - 1"])
    apply simp
    apply (simp add: field_simps)
   apply simp
   done
 
 lemma plus_1_less:
   "(x + 1 \<le> (x :: 'a :: len word)) = (x = -1)"
   apply (rule iffI)
    apply (rule ccontr)
    apply (cut_tac plus_one_helper2[where x=x, OF order_refl])
     apply simp
    apply clarsimp
    apply (drule arg_cong[where f="\<lambda>x. x - 1"])
    apply simp
   apply simp
   done
 
 lemma pos_mult_pos_ge:
   "[|x > (0::int); n>=0 |] ==> n * x >= n*1"
   apply (simp only: mult_left_mono)
   done
 
 lemma If_eq_obvious:
   "x \<noteq> z \<Longrightarrow> ((if P then x else y) = z) = (\<not> P \<and> y = z)"
   by simp
 
 lemma Some_to_the:
   "v = Some x \<Longrightarrow> x = the v"
   by simp
 
 lemma dom_if_Some:
   "dom (\<lambda>x. if P x then Some (f x) else g x) = {x. P x} \<union> dom g"
   by fastforce
 
 lemma dom_insert_absorb:
   "x \<in> dom f \<Longrightarrow> insert x (dom f) = dom f" by auto
 
 lemma emptyE2:
   "\<lbrakk> S = {}; x \<in> S \<rbrakk> \<Longrightarrow> P"
   by simp
 
 lemma mod_div_equality_div_eq:
   "a div b * b = (a - (a mod b) :: int)"
   by (simp add: field_simps)
 
 lemma zmod_helper:
   "n mod m = k \<Longrightarrow> ((n :: int) + a) mod m = (k + a) mod m"
   by (metis add.commute mod_add_right_eq)
 
 lemma int_div_sub_1:
   "\<lbrakk> m \<ge> 1 \<rbrakk> \<Longrightarrow> (n - (1 :: int)) div m = (if m dvd n then (n div m) - 1 else n div m)"
   apply (subgoal_tac "m = 0 \<or> (n - (1 :: int)) div m = (if m dvd n then (n div m) - 1 else n div m)")
    apply fastforce
   apply (subst mult_cancel_right[symmetric])
   apply (simp only: left_diff_distrib split: if_split)
   apply (simp only: mod_div_equality_div_eq)
   apply (clarsimp simp: field_simps)
   apply (clarsimp simp: dvd_eq_mod_eq_0)
   apply (cases "m = 1")
    apply simp
   apply (subst mod_diff_eq[symmetric], simp add: zmod_minus1)
   apply clarsimp
   apply (subst diff_add_cancel[where b=1, symmetric])
   apply (subst mod_add_eq[symmetric])
   apply (simp add: field_simps)
   apply (rule mod_pos_pos_trivial)
    apply (subst add_0_right[where a=0, symmetric])
    apply (rule add_mono)
     apply simp
    apply simp
   apply (cases "(n - 1) mod m = m - 1")
    apply (drule zmod_helper[where a=1])
    apply simp
   apply (subgoal_tac "1 + (n - 1) mod m \<le> m")
    apply simp
   apply (subst field_simps, rule zless_imp_add1_zle)
   apply simp
   done
 
 lemma ptr_add_image_multI:
   "\<lbrakk> \<And>x y. (x * val = y * val') = (x * val'' = y); x * val'' \<in> S \<rbrakk> \<Longrightarrow>
      ptr_add ptr (x * val) \<in> (\<lambda>p. ptr_add ptr (p * val')) ` S"
   apply (simp add: image_def)
   apply (erule rev_bexI)
   apply (rule arg_cong[where f="ptr_add ptr"])
   apply simp
   done
 
 lemma shift_times_fold:
   "(x :: 'a :: len word) * (2 ^ n) << m = x << (m + n)"
   by (simp add: shiftl_t2n ac_simps power_add)
 
 lemma word_plus_strict_mono_right:
   fixes x :: "'a :: len word"
   shows "\<lbrakk>y < z; x \<le> x + z\<rbrakk> \<Longrightarrow> x + y < x + z"
   by unat_arith
 
 lemma replicate_minus:
   "k < n \<Longrightarrow> replicate n False = replicate (n - k) False @ replicate k False"
   by (subst replicate_add [symmetric]) simp
 
 lemmas map_prod_split_imageI'
   = map_prod_imageI[where f="case_prod f" and g="case_prod g"
                     and a="(a, b)" and b="(c, d)" for a b c d f g]
 lemmas map_prod_split_imageI = map_prod_split_imageI'[simplified]
 
 lemma word_div_mult:
   "0 < c \<Longrightarrow> a < b * c \<Longrightarrow> a div c < b" for a b c :: "'a::len word"
   by (rule classical)
      (use div_to_mult_word_lt [of b a c] in
       \<open>auto simp add: word_less_nat_alt word_le_nat_alt unat_div\<close>)
 
 lemma word_less_power_trans_ofnat:
   "\<lbrakk>n < 2 ^ (m - k); k \<le> m; m < LENGTH('a)\<rbrakk>
    \<Longrightarrow> of_nat n * 2 ^ k < (2::'a::len word) ^ m"
   apply (subst mult.commute)
   apply (rule word_less_power_trans)
     apply (simp_all add: word_less_nat_alt less_le_trans take_bit_eq_mod)
   done
 
 lemma word_1_le_power:
   "n < LENGTH('a) \<Longrightarrow> (1 :: 'a :: len word) \<le> 2 ^ n"
   by (rule inc_le[where i=0, simplified], erule iffD2[OF p2_gt_0])
 
 lemma enum_word_div:
   fixes v :: "'a :: len word" shows
   "\<exists>xs ys. enum = xs @ [v] @ ys
              \<and> (\<forall>x \<in> set xs. x < v)
              \<and> (\<forall>y \<in> set ys. v < y)"
   apply (simp only: enum_word_def)
   apply (subst upt_add_eq_append'[where j="unat v"])
     apply simp
    apply (rule order_less_imp_le, simp)
   apply (simp add: upt_conv_Cons)
   apply (intro exI conjI)
     apply fastforce
    apply clarsimp
    apply (drule of_nat_mono_maybe[rotated, where 'a='a])
     apply simp
    apply simp
   apply (clarsimp simp: Suc_le_eq)
   apply (drule of_nat_mono_maybe[rotated, where 'a='a])
    apply simp
   apply simp
   done
 
 lemma of_bool_nth:
   "of_bool (x !! v) = (x >> v) && 1"
   by (simp add: test_bit_word_eq shiftr_word_eq bit_eq_iff)
     (auto simp add: bit_1_iff bit_and_iff bit_drop_bit_eq intro: ccontr)
 
 lemma unat_1_0:
   "1 \<le> (x::'a::len word) = (0 < unat x)"
   by (auto simp add: word_le_nat_alt)
 
 lemma x_less_2_0_1':
   fixes x :: "'a::len word"
   shows "\<lbrakk>LENGTH('a) \<noteq> 1; x < 2\<rbrakk> \<Longrightarrow> x = 0 \<or> x = 1"
   apply (cases \<open>2 \<le> LENGTH('a)\<close>)
   apply simp_all
   apply transfer
   apply auto
   apply (metis add.commute add.right_neutral even_two_times_div_two mod_div_trivial mod_pos_pos_trivial mult.commute mult_zero_left not_less not_take_bit_negative odd_two_times_div_two_succ) 
   done
 
 lemmas word_add_le_iff2 = word_add_le_iff [folded no_olen_add_nat]
 
 lemma of_nat_power:
   shows "\<lbrakk> p < 2 ^ x; x < len_of TYPE ('a) \<rbrakk> \<Longrightarrow> of_nat p < (2 :: 'a :: len word) ^ x"
   apply (rule order_less_le_trans)
    apply (rule of_nat_mono_maybe)
     apply (erule power_strict_increasing)
     apply simp
    apply assumption
   apply (simp add: word_unat_power)
   done
 
 lemma of_nat_n_less_equal_power_2:
   "n < LENGTH('a::len) \<Longrightarrow> ((of_nat n)::'a word) < 2 ^ n"
   apply (induct n)
    apply clarsimp
   apply clarsimp
   apply (metis of_nat_power n_less_equal_power_2 of_nat_Suc power_Suc)
   done
 
 lemma eq_mask_less:
   fixes w :: "'a::len word"
   assumes eqm: "w = w && mask n"
   and      sz: "n < len_of TYPE ('a)"
   shows "w < (2::'a word) ^ n"
   by (subst eqm, rule and_mask_less' [OF sz])
 
 lemma of_nat_mono_maybe':
   fixes Y :: "nat"
   assumes xlt: "x < 2 ^ len_of TYPE ('a)"
   assumes ylt: "y < 2 ^ len_of TYPE ('a)"
   shows   "(y < x) = (of_nat y < (of_nat x :: 'a :: len word))"
   apply (subst word_less_nat_alt)
   apply (subst unat_of_nat)+
   apply (subst mod_less)
    apply (rule ylt)
   apply (subst mod_less)
    apply (rule xlt)
   apply simp
   done
 
 lemma shiftr_mask_eq:
   "(x >> n) && mask (size x - n) = x >> n" for x :: "'a :: len word"
   by word_eqI_solve
 
 lemma shiftr_mask_eq':
   "m = (size x - n) \<Longrightarrow> (x >> n) && mask m = x >> n" for x :: "'a :: len word"
   by (simp add: shiftr_mask_eq)
 
 lemma dom_if:
   "dom (\<lambda>a. if a \<in> addrs then Some (f a) else g a)  = addrs \<union> dom g"
   by (auto simp: dom_def split: if_split)
 
 lemma less_is_non_zero_p1:
   fixes a :: "'a :: len word"
   shows "a < k \<Longrightarrow> a + 1 \<noteq> 0"
   apply (erule contrapos_pn)
   apply (drule max_word_wrap)
   apply (simp add: not_less)
   done
 
 lemma of_nat_mono_maybe_le:
   "\<lbrakk>x < 2 ^ LENGTH('a); y < 2 ^ LENGTH('a)\<rbrakk> \<Longrightarrow>
   (y \<le> x) = ((of_nat y :: 'a :: len word) \<le> of_nat x)"
   apply (clarsimp simp: le_less)
   apply (rule disj_cong)
    apply (rule of_nat_mono_maybe', assumption+)
   apply (simp add: word_unat.norm_eq_iff [symmetric])
   done
 
 lemma mask_AND_NOT_mask:
   "(w && ~~ (mask n)) && mask n = 0"
   by word_eqI
 
 lemma AND_NOT_mask_plus_AND_mask_eq:
   "(w && ~~ (mask n)) + (w && mask n) = w"
   by (subst word_plus_and_or_coroll; word_eqI_solve)
 
 lemma mask_eqI:
   fixes x :: "'a :: len word"
   assumes m1: "x && mask n = y && mask n"
   and     m2: "x && ~~ (mask n) = y && ~~ (mask n)"
   shows "x = y"
 proof (subst bang_eq, rule allI)
   fix m
 
   show "x !! m = y !! m"
   proof (cases "m < n")
     case True
     then have "x !! m = ((x && mask n) !! m)"
       by (simp add: word_size test_bit_conj_lt)
     also have "\<dots> = ((y && mask n) !! m)" using m1 by simp
     also have "\<dots> = y !! m" using True
       by (simp add: word_size test_bit_conj_lt)
     finally show ?thesis .
   next
     case False
     then have "x !! m = ((x && ~~ (mask n)) !! m)"
       by (simp add: neg_mask_test_bit test_bit_conj_lt)
     also have "\<dots> = ((y && ~~ (mask n)) !! m)" using m2 by simp
     also have "\<dots> = y !! m" using False
       by (simp add: neg_mask_test_bit test_bit_conj_lt)
     finally show ?thesis .
   qed
 qed
 
 lemma nat_less_power_trans2:
   fixes n :: nat
   shows "\<lbrakk>n < 2 ^ (m - k); k \<le> m\<rbrakk> \<Longrightarrow> n * 2 ^ k  < 2 ^ m"
   by (subst mult.commute, erule (1) nat_less_power_trans)
 
 lemma nat_move_sub_le: "(a::nat) + b \<le> c \<Longrightarrow> a \<le> c - b" by arith
 
 lemma neq_0_no_wrap:
   fixes x :: "'a :: len word"
   shows "\<lbrakk> x \<le> x + y; x \<noteq> 0 \<rbrakk> \<Longrightarrow> x + y \<noteq> 0"
   by clarsimp
 
 lemma plus_minus_one_rewrite:
   "v + (- 1 :: ('a :: {ring, one, uminus})) \<equiv> v - 1"
   by (simp add: field_simps)
 
 lemma power_minus_is_div:
   "b \<le> a \<Longrightarrow> (2 :: nat) ^ (a - b) = 2 ^ a div 2 ^ b"
   apply (induct a arbitrary: b)
    apply simp
   apply (erule le_SucE)
    apply (clarsimp simp:Suc_diff_le le_iff_add power_add)
   apply simp
   done
 
 lemma two_pow_div_gt_le:
   "v < 2 ^ n div (2 ^ m :: nat) \<Longrightarrow> m \<le> n"
   by (clarsimp dest!: less_two_pow_divD)
 
 lemma unatSuc2:
   fixes n :: "'a :: len word"
   shows "n + 1 \<noteq> 0 \<Longrightarrow> unat (n + 1) = Suc (unat n)"
   by (simp add: add.commute unatSuc)
 
 lemma word_of_nat_less:
   "\<lbrakk> n < unat x \<rbrakk> \<Longrightarrow> of_nat n < x"
   apply (simp add: word_less_nat_alt)
   apply (erule order_le_less_trans[rotated])
   apply (simp add: take_bit_eq_mod)
   done
 
 lemma word_of_nat_le:
   "n \<le> unat x \<Longrightarrow> of_nat n \<le> x"
   apply (simp add: word_le_nat_alt unat_of_nat)
   apply (erule order_trans[rotated])
   apply (simp add: take_bit_eq_mod)
   done
 
 lemma word_unat_less_le:
    "a \<le> of_nat b \<Longrightarrow> unat a \<le> b"
    by (metis eq_iff le_cases le_unat_uoi word_of_nat_le)
 
 lemma and_eq_0_is_nth:
   fixes x :: "'a :: len word"
   shows "y = 1 << n \<Longrightarrow> ((x && y) = 0) = (\<not> (x !! n))"
   apply safe
    apply (drule_tac u="(x && (1 << n))" and x=n in word_eqD)
    apply (simp add: nth_w2p)
    apply (simp add: test_bit_bin)
   apply word_eqI
   done
 
 lemmas arg_cong_Not = arg_cong [where f=Not]
 lemmas and_neq_0_is_nth = arg_cong_Not [OF and_eq_0_is_nth, simplified]
 
 lemma nth_is_and_neq_0:
   "(x::'a::len word) !! n = (x && 2 ^ n \<noteq> 0)"
   by (subst and_neq_0_is_nth; rule refl)
 
 lemma mask_Suc_0 : "mask (Suc 0) = (1 :: 'a::len word)"
   by (simp add: mask_eq_decr_exp)
 
 lemma ucast_ucast_add:
   fixes x :: "'a :: len word"
   fixes y :: "'b :: len word"
   shows
   "LENGTH('b) \<ge> LENGTH('a) \<Longrightarrow>
     ucast (ucast x + y) = x + ucast y"
   apply (rule word_unat.Rep_eqD)
   apply (simp add: unat_ucast unat_word_ariths mod_mod_power
                    min.absorb2 unat_of_nat)
   apply (subst mod_add_left_eq[symmetric])
   apply (simp add: mod_mod_power min.absorb2)
   apply (subst mod_add_right_eq)
   apply simp
   done
 
 lemma word_shift_zero:
   "\<lbrakk> x << n = 0; x \<le> 2^m; m + n < LENGTH('a)\<rbrakk> \<Longrightarrow> (x::'a::len word) = 0"
   apply (rule ccontr)
   apply (drule (2) word_shift_nonzero)
   apply simp
   done
 
 lemma bool_mask':
   fixes x :: "'a :: len word"
   shows "2 < LENGTH('a) \<Longrightarrow> (0 < x && 1) = (x && 1 = 1)"
   by (simp add: and_one_eq mod_2_eq_odd)
 
 lemma sint_eq_uint:
   "\<not> msb x \<Longrightarrow> sint x = uint x"
   apply (rule word_uint.Abs_eqD, subst word_sint.Rep_inverse)
     apply simp_all
   apply (cut_tac x=x in word_sint.Rep)
   apply (clarsimp simp add: uints_num sints_num)
   apply (rule conjI)
    apply (rule ccontr)
    apply (simp add: linorder_not_le word_msb_sint[symmetric])
   apply (erule order_less_le_trans)
   apply simp
   done
 
 lemma scast_eq_ucast:
   "\<not> msb x \<Longrightarrow> scast x = ucast x"
   apply (cases \<open>LENGTH('a)\<close>)
   apply simp
   apply (rule bit_word_eqI)
   apply (auto simp add: bit_signed_iff bit_unsigned_iff min_def msb_word_eq)
   apply (erule notE)
   apply (metis le_less_Suc_eq test_bit_bin test_bit_word_eq)
   done
 
 lemma lt1_neq0:
   fixes x :: "'a :: len word"
   shows "(1 \<le> x) = (x \<noteq> 0)" by unat_arith
 
 lemma word_plus_one_nonzero:
   fixes x :: "'a :: len word"
   shows "\<lbrakk>x \<le> x + y; y \<noteq> 0\<rbrakk> \<Longrightarrow> x + 1 \<noteq> 0"
   apply (subst lt1_neq0 [symmetric])
   apply (subst olen_add_eqv [symmetric])
   apply (erule word_random)
   apply (simp add: lt1_neq0)
   done
 
 lemma word_sub_plus_one_nonzero:
   fixes n :: "'a :: len word"
   shows "\<lbrakk>n' \<le> n; n' \<noteq> 0\<rbrakk> \<Longrightarrow> (n - n') + 1 \<noteq> 0"
   apply (subst lt1_neq0 [symmetric])
   apply (subst olen_add_eqv [symmetric])
   apply (rule word_random [where x' = n'])
    apply simp
    apply (erule word_sub_le)
   apply (simp add: lt1_neq0)
   done
 
 lemma word_le_minus_mono_right:
   fixes x :: "'a :: len word"
   shows "\<lbrakk> z \<le> y; y \<le> x; z \<le> x \<rbrakk> \<Longrightarrow> x - y \<le> x - z"
   apply (rule word_sub_mono)
      apply simp
     apply assumption
    apply (erule word_sub_le)
   apply (erule word_sub_le)
   done
 
 lemma drop_append_miracle:
   "n = length xs \<Longrightarrow> drop n (xs @ ys) = ys"
   by simp
 
 lemma foldr_does_nothing_to_xf:
   "\<lbrakk> \<And>x s. x \<in> set xs \<Longrightarrow> xf (f x s) = xf s \<rbrakk> \<Longrightarrow> xf (foldr f xs s) = xf s"
   by (induct xs, simp_all)
 
 lemma nat_less_mult_monoish: "\<lbrakk> a < b; c < (d :: nat) \<rbrakk> \<Longrightarrow> (a + 1) * (c + 1) <= b * d"
   apply (drule Suc_leI)+
   apply (drule(1) mult_le_mono)
   apply simp
   done
 
 lemma word_0_sle_from_less[unfolded word_size]:
   "\<lbrakk> x < 2 ^ (size x - 1) \<rbrakk>  \<Longrightarrow> 0 <=s x"
   apply (clarsimp simp: word_sle_msb_le)
   apply (simp add: word_msb_nth)
   apply (subst (asm) word_test_bit_def [symmetric])
   apply (drule less_mask_eq)
   apply (drule_tac x="size x - 1" in word_eqD)
   apply (simp add: word_size)
   done
 
 lemma not_msb_from_less:
   "(v :: 'a word) < 2 ^ (LENGTH('a :: len) - 1) \<Longrightarrow> \<not> msb v"
   apply (clarsimp simp add: msb_nth)
   apply (drule less_mask_eq)
   apply (drule word_eqD, drule(1) iffD2)
   apply simp
   done
 
 lemma distinct_lemma: "f x \<noteq> f y \<Longrightarrow> x \<noteq> y" by auto
 
 
 lemma ucast_sub_ucast:
   fixes x :: "'a::len word"
   assumes "y \<le> x"
   assumes T: "LENGTH('a) \<le> LENGTH('b)"
   shows "ucast (x - y) = (ucast x - ucast y :: 'b::len word)"
 proof -
   from T
   have P: "unat x < 2 ^ LENGTH('b)" "unat y < 2 ^ LENGTH('b)"
     by (fastforce intro!: less_le_trans[OF unat_lt2p])+
   then show ?thesis
     by (simp add: unat_arith_simps unat_ucast assms[simplified unat_arith_simps])
 qed
 
 lemma word_1_0:
   "\<lbrakk>a + (1::('a::len) word) \<le> b; a < of_nat x\<rbrakk> \<Longrightarrow> a < b"
   apply transfer
   apply (subst (asm) take_bit_incr_eq)
    apply (auto simp add: diff_less_eq)
   using take_bit_int_less_exp le_less_trans by blast
 
 lemma unat_of_nat_less:"\<lbrakk> a < b; unat b = c \<rbrakk> \<Longrightarrow> a < of_nat c"
   by fastforce
 
 lemma word_le_plus_1: "\<lbrakk> (y::('a::len) word) < y + n; a < n \<rbrakk> \<Longrightarrow> y + a \<le> y + a + 1"
   by unat_arith
 
 lemma word_le_plus:"\<lbrakk>(a::('a::len) word) < a + b; c < b\<rbrakk> \<Longrightarrow> a \<le> a + c"
 by (metis order_less_imp_le word_random)
 
 (*
  * Basic signed arithemetic properties.
  *)
 
 lemma sint_minus1 [simp]: "(sint x = -1) = (x = -1)"
   by (metis sint_n1 word_sint.Rep_inverse')
 
 lemma sint_0 [simp]: "(sint x = 0) = (x = 0)"
   by (metis sint_0 word_sint.Rep_inverse')
 
 (* It is not always that case that "sint 1 = 1", because of 1-bit word sizes.
  * This lemma produces the different cases. *)
 lemma sint_1_cases:
   P if \<open>\<lbrakk> len_of TYPE ('a::len) = 1; (a::'a word) = 0; sint a = 0 \<rbrakk> \<Longrightarrow> P\<close>
      \<open>\<lbrakk> len_of TYPE ('a) = 1; a = 1; sint (1 :: 'a word) = -1 \<rbrakk> \<Longrightarrow> P\<close>
      \<open>\<lbrakk> len_of TYPE ('a) > 1; sint (1 :: 'a word) = 1 \<rbrakk> \<Longrightarrow> P\<close>
 proof (cases \<open>LENGTH('a) = 1\<close>)
   case True
   then have \<open>a = 0 \<or> a = 1\<close>
     by transfer auto
   with True that show ?thesis
     by auto
 next
   case False
   with that show ?thesis
     by (simp add: less_le Suc_le_eq)
 qed
 
 lemma sint_int_min:
   "sint (- (2 ^ (LENGTH('a) - Suc 0)) :: ('a::len) word) = - (2 ^ (LENGTH('a) - Suc 0))"
   apply (subst word_sint.Abs_inverse' [where r="- (2 ^ (LENGTH('a) - Suc 0))"])
     apply (clarsimp simp: sints_num)
    apply (clarsimp simp: wi_hom_syms word_of_int_2p)
   apply clarsimp
   done
 
 lemma sint_int_max_plus_1:
   "sint (2 ^ (LENGTH('a) - Suc 0) :: ('a::len) word) = - (2 ^ (LENGTH('a) - Suc 0))"
   apply (cases \<open>LENGTH('a)\<close>)
    apply simp_all
   apply (subst word_of_int_2p [symmetric])
   apply (subst int_word_sint)
   apply simp
   done
 
 lemma sbintrunc_eq_in_range:
   "(sbintrunc n x = x) = (x \<in> range (sbintrunc n))"
   "(x = sbintrunc n x) = (x \<in> range (sbintrunc n))"
   apply (simp_all add: image_def)
   apply (metis sbintrunc_sbintrunc)+
   done
 
 lemma sbintrunc_If:
   "- 3 * (2 ^ n) \<le> x \<and> x < 3 * (2 ^ n)
     \<Longrightarrow> sbintrunc n x = (if x < - (2 ^ n) then x + 2 * (2 ^ n)
         else if x \<ge> 2 ^ n then x - 2 * (2 ^ n) else x)"
   apply (simp add: no_sbintr_alt2, safe)
    apply (simp add: mod_pos_geq)
   apply (subst mod_add_self1[symmetric], simp)
   done
 
 lemma signed_arith_eq_checks_to_ord:
   "(sint a + sint b = sint (a + b ))
     = ((a <=s a + b) = (0 <=s b))"
   "(sint a - sint b = sint (a - b ))
     = ((0 <=s a - b) = (b <=s a))"
   "(- sint a = sint (- a)) = (0 <=s (- a) = (a <=s 0))"
   using sint_range'[where x=a] sint_range'[where x=b]
   by (simp_all add: sint_word_ariths word_sle_eq word_sless_alt sbintrunc_If)
 
 (* Basic proofs that signed word div/mod operations are
  * truncations of their integer counterparts. *)
 
 lemma signed_div_arith:
     "sint ((a::('a::len) word) sdiv b) = sbintrunc (LENGTH('a) - 1) (sint a sdiv sint b)"
   apply (subst word_sbin.norm_Rep [symmetric])
   apply (subst bin_sbin_eq_iff' [symmetric])
    apply simp
   apply (subst uint_sint [symmetric])
   apply (clarsimp simp: sdiv_int_def sdiv_word_def)
   apply transfer
   apply simp
   done
 
 lemma signed_mod_arith:
     "sint ((a::('a::len) word) smod b) = sbintrunc (LENGTH('a) - 1) (sint a smod sint b)"
  
   apply (subst word_sbin.norm_Rep [symmetric])
   apply (subst bin_sbin_eq_iff' [symmetric])
    apply simp
   apply (subst uint_sint [symmetric])
   apply (clarsimp simp: smod_int_def smod_word_def)
   using word_ubin.inverse_norm by force
 
 (* Signed word arithmetic overflow constraints. *)
 
 lemma signed_arith_ineq_checks_to_eq:
   "((- (2 ^ (size a - 1)) \<le> (sint a + sint b)) \<and> (sint a + sint b \<le> (2 ^ (size a - 1) - 1)))
     = (sint a + sint b = sint (a + b ))"
   "((- (2 ^ (size a - 1)) \<le> (sint a - sint b)) \<and> (sint a - sint b \<le> (2 ^ (size a - 1) - 1)))
     = (sint a - sint b = sint (a - b))"
   "((- (2 ^ (size a - 1)) \<le> (- sint a)) \<and> (- sint a) \<le> (2 ^ (size a - 1) - 1))
     = ((- sint a) = sint (- a))"
   "((- (2 ^ (size a - 1)) \<le> (sint a * sint b)) \<and> (sint a * sint b \<le> (2 ^ (size a - 1) - 1)))
     = (sint a * sint b = sint (a * b))"
   "((- (2 ^ (size a - 1)) \<le> (sint a sdiv sint b)) \<and> (sint a sdiv sint b \<le> (2 ^ (size a - 1) - 1)))
     = (sint a sdiv sint b = sint (a sdiv b))"
   "((- (2 ^ (size a - 1)) \<le> (sint a smod sint b)) \<and> (sint a smod sint b \<le> (2 ^ (size a - 1) - 1)))
     = (sint a smod sint b = sint (a smod b))"
   by (auto simp: sint_word_ariths word_size signed_div_arith signed_mod_arith
                     sbintrunc_eq_in_range range_sbintrunc)
 
 lemma signed_arith_sint:
   "((- (2 ^ (size a - 1)) \<le> (sint a + sint b)) \<and> (sint a + sint b \<le> (2 ^ (size a - 1) - 1)))
     \<Longrightarrow> sint (a + b) = (sint a + sint b)"
   "((- (2 ^ (size a - 1)) \<le> (sint a - sint b)) \<and> (sint a - sint b \<le> (2 ^ (size a - 1) - 1)))
     \<Longrightarrow> sint (a - b) = (sint a - sint b)"
   "((- (2 ^ (size a - 1)) \<le> (- sint a)) \<and> (- sint a) \<le> (2 ^ (size a - 1) - 1))
     \<Longrightarrow> sint (- a) = (- sint a)"
   "((- (2 ^ (size a - 1)) \<le> (sint a * sint b)) \<and> (sint a * sint b \<le> (2 ^ (size a - 1) - 1)))
     \<Longrightarrow> sint (a * b) = (sint a * sint b)"
   "((- (2 ^ (size a - 1)) \<le> (sint a sdiv sint b)) \<and> (sint a sdiv sint b \<le> (2 ^ (size a - 1) - 1)))
     \<Longrightarrow> sint (a sdiv b) = (sint a sdiv sint b)"
   "((- (2 ^ (size a - 1)) \<le> (sint a smod sint b)) \<and> (sint a smod sint b \<le> (2 ^ (size a - 1) - 1)))
     \<Longrightarrow> sint (a smod b) = (sint a smod sint b)"
   by (subst (asm) signed_arith_ineq_checks_to_eq; simp)+
 
 lemma signed_mult_eq_checks_double_size:
   assumes mult_le: "(2 ^ (len_of TYPE ('a) - 1) + 1) ^ 2 \<le> (2 :: int) ^ (len_of TYPE ('b) - 1)"
            and le: "2 ^ (LENGTH('a) - 1) \<le> (2 :: int) ^ (len_of TYPE ('b) - 1)"
   shows "(sint (a :: 'a :: len word) * sint b = sint (a * b))
        = (scast a * scast b = (scast (a * b) :: 'b :: len word))"
 proof -
   have P: "sbintrunc (size a - 1) (sint a * sint b) \<in> range (sbintrunc (size a - 1))"
     by simp
 
   have abs: "!! x :: 'a word. abs (sint x) < 2 ^ (size a - 1) + 1"
     apply (cut_tac x=x in sint_range')
     apply (simp add: abs_le_iff word_size)
     done
   have abs_ab: "abs (sint a * sint b) < 2 ^ (LENGTH('b) - 1)"
     using abs_mult_less[OF abs[where x=a] abs[where x=b]] mult_le
     by (simp add: abs_mult power2_eq_square word_size)
   define r s where \<open>r = LENGTH('a) - 1\<close> \<open>s = LENGTH('b) - 1\<close>
   then have \<open>LENGTH('a) = Suc r\<close> \<open>LENGTH('b) = Suc s\<close>
     \<open>size a = Suc r\<close> \<open>size b = Suc r\<close>
     by (simp_all add: word_size)
   then show ?thesis
     using P[unfolded range_sbintrunc] abs_ab le
     apply clarsimp
     apply (transfer fixing: r s)
     apply (auto simp add: signed_take_bit_int_eq_self simp flip: signed_take_bit_eq_iff_take_bit_eq)
     done
 qed
 
 (* Properties about signed division. *)
 
 lemma int_sdiv_simps [simp]:
     "(a :: int) sdiv 1 = a"
     "(a :: int) sdiv 0 = 0"
     "(a :: int) sdiv -1 = -a"
   apply (auto simp: sdiv_int_def sgn_if)
   done
 
 lemma sgn_div_eq_sgn_mult:
     "a div b \<noteq> 0 \<Longrightarrow> sgn ((a :: int) div b) = sgn (a * b)"
   apply (clarsimp simp: sgn_if zero_le_mult_iff neg_imp_zdiv_nonneg_iff not_less)
   apply (metis less_le mult_le_0_iff neg_imp_zdiv_neg_iff not_less pos_imp_zdiv_neg_iff zdiv_eq_0_iff)
   done
 
 lemma sgn_sdiv_eq_sgn_mult:
   "a sdiv b \<noteq> 0 \<Longrightarrow> sgn ((a :: int) sdiv b) = sgn (a * b)"
   by (auto simp: sdiv_int_def sgn_div_eq_sgn_mult sgn_mult)
 
 lemma int_sdiv_same_is_1 [simp]:
     "a \<noteq> 0 \<Longrightarrow> ((a :: int) sdiv b = a) = (b = 1)"
   apply (rule iffI)
    apply (clarsimp simp: sdiv_int_def)
    apply (subgoal_tac "b > 0")
     apply (case_tac "a > 0")
      apply (clarsimp simp: sgn_if)
     apply (clarsimp simp: algebra_split_simps not_less)
     apply (metis int_div_same_is_1 le_neq_trans minus_minus neg_0_le_iff_le neg_equal_0_iff_equal)
    apply (case_tac "a > 0")
     apply (case_tac "b = 0")
      apply clarsimp
     apply (rule classical)
     apply (clarsimp simp: sgn_mult not_less)
     apply (metis le_less neg_0_less_iff_less not_less_iff_gr_or_eq pos_imp_zdiv_neg_iff)
    apply (rule classical)
    apply (clarsimp simp: algebra_split_simps sgn_mult not_less sgn_if split: if_splits)
    apply (metis antisym less_le neg_imp_zdiv_nonneg_iff)
   apply (clarsimp simp: sdiv_int_def sgn_if)
   done
 
 lemma int_sdiv_negated_is_minus1 [simp]:
     "a \<noteq> 0 \<Longrightarrow> ((a :: int) sdiv b = - a) = (b = -1)"
   apply (clarsimp simp: sdiv_int_def)
   apply (rule iffI)
    apply (subgoal_tac "b < 0")
     apply (case_tac "a > 0")
      apply (clarsimp simp: sgn_if algebra_split_simps not_less)
     apply (case_tac "sgn (a * b) = -1")
      apply (clarsimp simp: not_less algebra_split_simps)
     apply (clarsimp simp: algebra_split_simps not_less)
    apply (rule classical)
    apply (case_tac "b = 0")
     apply (clarsimp simp: not_less sgn_mult)
    apply (case_tac "a > 0")
     apply (clarsimp simp: not_less sgn_mult)
     apply (metis less_le neg_less_0_iff_less not_less_iff_gr_or_eq pos_imp_zdiv_neg_iff)
    apply (clarsimp simp: not_less sgn_mult)
    apply (metis antisym_conv div_minus_right neg_imp_zdiv_nonneg_iff neg_le_0_iff_le not_less)
   apply (clarsimp simp: sgn_if)
   done
 
 lemma sdiv_int_range:
     "(a :: int) sdiv b \<in> { - (abs a) .. (abs a) }"
   apply (unfold sdiv_int_def)
   apply (subgoal_tac "(abs a) div (abs b) \<le> (abs a)")
    apply (auto simp add: sgn_if not_less)
       apply (metis le_less le_less_trans neg_equal_0_iff_equal neg_less_iff_less not_le pos_imp_zdiv_neg_iff)
      apply (metis add.inverse_neutral div_int_pos_iff le_less neg_le_iff_le order_trans)
     apply (metis div_minus_right le_less_trans neg_imp_zdiv_neg_iff neg_less_0_iff_less not_le)
   using div_int_pos_iff apply fastforce
   apply (metis abs_0_eq abs_ge_zero div_by_0 zdiv_le_dividend zero_less_abs_iff)
   done
 
 lemma word_sdiv_div1 [simp]:
     "(a :: ('a::len) word) sdiv 1 = a"
   apply (rule sint_1_cases [where a=a])
     apply (clarsimp simp: sdiv_word_def sdiv_int_def)
    apply (clarsimp simp: sdiv_word_def sdiv_int_def simp del: sint_minus1)
   apply (clarsimp simp: sdiv_word_def)
   done
 
 lemma sdiv_int_div_0 [simp]:
   "(x :: int) sdiv 0 = 0"
   by (clarsimp simp: sdiv_int_def)
 
 lemma sdiv_int_0_div [simp]:
   "0 sdiv (x :: int) = 0"
   by (clarsimp simp: sdiv_int_def)
 
 lemma word_sdiv_div0 [simp]:
     "(a :: ('a::len) word) sdiv 0 = 0"
   apply (auto simp: sdiv_word_def sdiv_int_def sgn_if)
   done
 
 lemma word_sdiv_div_minus1 [simp]:
     "(a :: ('a::len) word) sdiv -1 = -a"
   apply (auto simp: sdiv_word_def sdiv_int_def sgn_if)
   done
 
 lemmas word_sdiv_0 = word_sdiv_div0
 
 lemma sdiv_word_min:
     "- (2 ^ (size a - 1)) \<le> sint (a :: ('a::len) word) sdiv sint (b :: ('a::len) word)"
   apply (clarsimp simp: word_size)
   apply (cut_tac sint_range' [where x=a])
   apply (cut_tac sint_range' [where x=b])
   apply clarsimp
   apply (insert sdiv_int_range [where a="sint a" and b="sint b"])
   apply (clarsimp simp: max_def abs_if split: if_split_asm)
   done
 
 lemma sdiv_word_max:
     "(sint (a :: ('a::len) word) sdiv sint (b :: ('a::len) word) < (2 ^ (size a - 1))) =
           ((a \<noteq> - (2 ^ (size a - 1)) \<or> (b \<noteq> -1)))"
     (is "?lhs = (\<not> ?a_int_min \<or> \<not> ?b_minus1)")
 proof (rule classical)
   assume not_thesis: "\<not> ?thesis"
 
   have not_zero: "b \<noteq> 0"
     using not_thesis
     by (clarsimp)
 
   have result_range: "sint a sdiv sint b \<in> (sints (size a)) \<union> {2 ^ (size a - 1)}"
     apply (cut_tac sdiv_int_range [where a="sint a" and b="sint b"])
     apply (erule rev_subsetD)
     using sint_range' [where x=a]  sint_range' [where x=b]
     apply (auto simp: max_def abs_if word_size sints_num)
     done
 
   have result_range_overflow: "(sint a sdiv sint b = 2 ^ (size a - 1)) = (?a_int_min \<and> ?b_minus1)"
     apply (rule iffI [rotated])
      apply (clarsimp simp: sdiv_int_def sgn_if word_size sint_int_min)
     apply (rule classical)
     apply (case_tac "?a_int_min")
      apply (clarsimp simp: word_size sint_int_min)
      apply (metis diff_0_right
               int_sdiv_negated_is_minus1 minus_diff_eq minus_int_code(2)
               power_eq_0_iff sint_minus1 zero_neq_numeral)
     apply (subgoal_tac "abs (sint a) < 2 ^ (size a - 1)")
      apply (insert sdiv_int_range [where a="sint a" and b="sint b"])[1]
      apply (clarsimp simp: word_size)
     apply (insert sdiv_int_range [where a="sint a" and b="sint b"])[1]
     apply (insert word_sint.Rep [where x="a"])[1]
     apply (clarsimp simp: minus_le_iff word_size abs_if sints_num split: if_split_asm)
     apply (metis minus_minus sint_int_min word_sint.Rep_inject)
     done
 
   have result_range_simple: "(sint a sdiv sint b \<in> (sints (size a))) \<Longrightarrow> ?thesis"
     apply (insert sdiv_int_range [where a="sint a" and b="sint b"])
     apply (clarsimp simp: word_size sints_num sint_int_min)
     done
 
   show ?thesis
     apply (rule UnE [OF result_range result_range_simple])
      apply simp
     apply (clarsimp simp: word_size)
     using result_range_overflow
     apply (clarsimp simp: word_size)
     done
 qed
 
 lemmas sdiv_word_min' = sdiv_word_min [simplified word_size, simplified]
 lemmas sdiv_word_max' = sdiv_word_max [simplified word_size, simplified]
 
 lemmas word_sdiv_numerals_lhs = sdiv_word_def[where v="numeral x" for x]
     sdiv_word_def[where v=0] sdiv_word_def[where v=1]
 
 lemmas word_sdiv_numerals = word_sdiv_numerals_lhs[where w="numeral y" for y]
     word_sdiv_numerals_lhs[where w=0] word_sdiv_numerals_lhs[where w=1]
 
 (*
  * Signed modulo properties.
  *)
 
 lemma smod_int_alt_def:
      "(a::int) smod b = sgn (a) * (abs a mod abs b)"
   apply (clarsimp simp: smod_int_def sdiv_int_def)
   apply (clarsimp simp: minus_div_mult_eq_mod [symmetric] abs_sgn sgn_mult sgn_if algebra_split_simps)
   done
 
 lemma smod_int_range:
   "b \<noteq> 0 \<Longrightarrow> (a::int) smod b \<in> { - abs b + 1 .. abs b - 1 }"
   apply (case_tac  "b > 0")
    apply (insert pos_mod_conj [where a=a and b=b])[1]
    apply (insert pos_mod_conj [where a="-a" and b=b])[1]
    apply (auto simp: smod_int_alt_def algebra_simps sgn_if
               abs_if not_less add1_zle_eq [simplified add.commute])[1]
     apply (metis add_nonneg_nonneg int_one_le_iff_zero_less le_less less_add_same_cancel2 not_le pos_mod_conj)
   apply (metis (full_types) add.inverse_inverse eucl_rel_int eucl_rel_int_iff le_less_trans neg_0_le_iff_le)
   apply (insert neg_mod_conj [where a=a and b="b"])[1]
   apply (insert neg_mod_conj [where a="-a" and b="b"])[1]
   apply (clarsimp simp: smod_int_alt_def algebra_simps sgn_if
             abs_if not_less add1_zle_eq [simplified add.commute])
   apply (metis neg_0_less_iff_less neg_mod_conj not_le not_less_iff_gr_or_eq order_trans pos_mod_conj)
   done
 
 lemma smod_int_compares:
    "\<lbrakk> 0 \<le> a; 0 < b \<rbrakk> \<Longrightarrow> (a :: int) smod b < b"
    "\<lbrakk> 0 \<le> a; 0 < b \<rbrakk> \<Longrightarrow> 0 \<le> (a :: int) smod b"
    "\<lbrakk> a \<le> 0; 0 < b \<rbrakk> \<Longrightarrow> -b < (a :: int) smod b"
    "\<lbrakk> a \<le> 0; 0 < b \<rbrakk> \<Longrightarrow> (a :: int) smod b \<le> 0"
    "\<lbrakk> 0 \<le> a; b < 0 \<rbrakk> \<Longrightarrow> (a :: int) smod b < - b"
    "\<lbrakk> 0 \<le> a; b < 0 \<rbrakk> \<Longrightarrow> 0 \<le> (a :: int) smod b"
    "\<lbrakk> a \<le> 0; b < 0 \<rbrakk> \<Longrightarrow> (a :: int) smod b \<le> 0"
    "\<lbrakk> a \<le> 0; b < 0 \<rbrakk> \<Longrightarrow> b \<le> (a :: int) smod b"
   apply (insert smod_int_range [where a=a and b=b])
   apply (auto simp: add1_zle_eq smod_int_alt_def sgn_if)
   done
 
 lemma smod_int_mod_0 [simp]:
   "x smod (0 :: int) = x"
   by (clarsimp simp: smod_int_def)
 
 lemma smod_int_0_mod [simp]:
   "0 smod (x :: int) = 0"
   by (clarsimp simp: smod_int_alt_def)
 
 lemma smod_word_mod_0 [simp]:
   "x smod (0 :: ('a::len) word) = x"
   by (clarsimp simp: smod_word_def)
 
 lemma smod_word_0_mod [simp]:
   "0 smod (x :: ('a::len) word) = 0"
   by (clarsimp simp: smod_word_def)
 
 lemma smod_word_max:
     "sint (a::'a word) smod sint (b::'a word) < 2 ^ (LENGTH('a::len) - Suc 0)"
   apply (case_tac "b = 0")
    apply (insert word_sint.Rep [where x=a, simplified sints_num])[1]
    apply (clarsimp)
   apply (insert word_sint.Rep [where x="b", simplified sints_num])[1]
   apply (insert smod_int_range [where a="sint a" and b="sint b"])
   apply (clarsimp simp: abs_if split: if_split_asm)
   done
 
 lemma smod_word_min:
     "- (2 ^ (LENGTH('a::len) - Suc 0)) \<le> sint (a::'a word) smod sint (b::'a word)"
   apply (case_tac "b = 0")
    apply (insert word_sint.Rep [where x=a, simplified sints_num])[1]
    apply clarsimp
   apply (insert word_sint.Rep [where x=b, simplified sints_num])[1]
   apply (insert smod_int_range [where a="sint a" and b="sint b"])
   apply (clarsimp simp: abs_if add1_zle_eq split: if_split_asm)
   done
 
 lemma smod_word_alt_def:
   "(a :: ('a::len) word) smod b = a - (a sdiv b) * b"
   apply (cases \<open>a \<noteq> - (2 ^ (LENGTH('a) - 1)) \<or> b \<noteq> - 1\<close>)
    apply (clarsimp simp: smod_word_def sdiv_word_def smod_int_def
      simp flip: wi_hom_sub wi_hom_mult)
   apply (clarsimp simp: smod_word_def smod_int_def)
   done
 
 lemmas word_smod_numerals_lhs = smod_word_def[where v="numeral x" for x]
     smod_word_def[where v=0] smod_word_def[where v=1]
 
 lemmas word_smod_numerals = word_smod_numerals_lhs[where w="numeral y" for y]
     word_smod_numerals_lhs[where w=0] word_smod_numerals_lhs[where w=1]
 
 lemma sint_of_int_eq:
   "\<lbrakk> - (2 ^ (LENGTH('a) - 1)) \<le> x; x < 2 ^ (LENGTH('a) - 1) \<rbrakk> \<Longrightarrow> sint (of_int x :: ('a::len) word) = x"
   by (simp add: signed_take_bit_int_eq_self)
 
 lemma of_int_sint:
   "of_int (sint a) = a"
   by simp
 
 lemma nth_w2p_scast [simp]:
   "((scast ((2::'a::len signed word) ^ n) :: 'a word) !! m)
          \<longleftrightarrow> ((((2::'a::len  word) ^ n) :: 'a word) !! m)"
   apply (subst nth_w2p)
   apply (case_tac "n \<ge> LENGTH('a)")
    apply (subst power_overflow, simp)
    apply clarsimp
   apply (metis nth_w2p scast_eq test_bit_conj_lt
                len_signed nth_word_of_int word_sint.Rep_inverse)
   done
 
 lemma scast_2_power [simp]: "scast ((2 :: 'a::len signed word) ^ x) = ((2 :: 'a word) ^ x)"
   by (clarsimp simp: word_eq_iff)
 
 lemma scast_bit_test [simp]:
     "scast ((1 :: 'a::len signed word) << n) = (1 :: 'a word) << n"
   by (clarsimp simp: word_eq_iff)
 
 lemma ucast_nat_def':
   "of_nat (unat x) = (ucast :: 'a :: len word \<Rightarrow> ('b :: len) signed word) x"
   by (fact ucast_nat_def)
 
 lemma mod_mod_power_int:
   fixes k :: int
   shows "k mod 2 ^ m mod 2 ^ n = k mod 2 ^ (min m n)"
   by (metis bintrunc_bintrunc_min bintrunc_mod2p min.commute)
 
 (* Normalise combinations of scast and ucast. *)
 
 lemma ucast_distrib:
   fixes M :: "'a::len word \<Rightarrow> 'a::len word \<Rightarrow> 'a::len word"
   fixes M' :: "'b::len word \<Rightarrow> 'b::len word \<Rightarrow> 'b::len word"
   fixes L :: "int \<Rightarrow> int \<Rightarrow> int"
   assumes lift_M: "\<And>x y. uint (M x y) = L (uint x) (uint y)  mod 2 ^ LENGTH('a)"
   assumes lift_M': "\<And>x y. uint (M' x y) = L (uint x) (uint y)  mod 2 ^ LENGTH('b)"
   assumes distrib: "\<And>x y. (L (x mod (2 ^ LENGTH('b))) (y mod (2 ^ LENGTH('b)))) mod (2 ^ LENGTH('b))
                                = (L x y) mod (2 ^ LENGTH('b))"
   assumes is_down: "is_down (ucast :: 'a word \<Rightarrow> 'b word)"
   shows "ucast (M a b) = M' (ucast a) (ucast b)"
   apply (simp only: ucast_eq)
   apply (subst lift_M)
   apply (subst of_int_uint [symmetric], subst lift_M')
   apply (subst (1 2) int_word_uint)
   apply (subst word_ubin.norm_eq_iff [symmetric])
   apply (subst (1 2) bintrunc_mod2p)
   apply (insert is_down)
   apply (unfold is_down_def)
   apply (clarsimp simp: target_size source_size)
   apply (clarsimp simp: mod_mod_power_int min_def)
   apply (rule distrib [symmetric])
   done
 
 lemma ucast_down_add:
     "is_down (ucast:: 'a word \<Rightarrow> 'b word) \<Longrightarrow>  ucast ((a :: 'a::len word) + b) = (ucast a + ucast b :: 'b::len word)"
   by (rule ucast_distrib [where L="(+)"], (clarsimp simp: uint_word_ariths)+, presburger, simp)
 
 lemma ucast_down_minus:
     "is_down (ucast:: 'a word \<Rightarrow> 'b word) \<Longrightarrow>  ucast ((a :: 'a::len word) - b) = (ucast a - ucast b :: 'b::len word)"
   apply (rule ucast_distrib [where L="(-)"], (clarsimp simp: uint_word_ariths)+)
   apply (metis mod_diff_left_eq mod_diff_right_eq)
   apply simp
   done
 
 lemma ucast_down_mult:
     "is_down (ucast:: 'a word \<Rightarrow> 'b word) \<Longrightarrow>  ucast ((a :: 'a::len word) * b) = (ucast a * ucast b :: 'b::len word)"
   apply (rule ucast_distrib [where L="(*)"], (clarsimp simp: uint_word_ariths)+)
   apply (metis mod_mult_eq)
   apply simp
   done
 
 lemma scast_distrib:
   fixes M :: "'a::len word \<Rightarrow> 'a::len word \<Rightarrow> 'a::len word"
   fixes M' :: "'b::len word \<Rightarrow> 'b::len word \<Rightarrow> 'b::len word"
   fixes L :: "int \<Rightarrow> int \<Rightarrow> int"
   assumes lift_M: "\<And>x y. uint (M x y) = L (uint x) (uint y)  mod 2 ^ LENGTH('a)"
   assumes lift_M': "\<And>x y. uint (M' x y) = L (uint x) (uint y)  mod 2 ^ LENGTH('b)"
   assumes distrib: "\<And>x y. (L (x mod (2 ^ LENGTH('b))) (y mod (2 ^ LENGTH('b)))) mod (2 ^ LENGTH('b))
                                = (L x y) mod (2 ^ LENGTH('b))"
   assumes is_down: "is_down (scast :: 'a word \<Rightarrow> 'b word)"
   shows "scast (M a b) = M' (scast a) (scast b)"
   apply (subst (1 2 3) down_cast_same [symmetric])
    apply (insert is_down)
    apply (clarsimp simp: is_down_def target_size source_size is_down)
   apply (rule ucast_distrib [where L=L, OF lift_M lift_M' distrib])
   apply (insert is_down)
   apply (clarsimp simp: is_down_def target_size source_size is_down)
   done
 
 lemma scast_down_add:
     "is_down (scast:: 'a word \<Rightarrow> 'b word) \<Longrightarrow>  scast ((a :: 'a::len word) + b) = (scast a + scast b :: 'b::len word)"
   by (rule scast_distrib [where L="(+)"], (clarsimp simp: uint_word_ariths)+, presburger, simp)
 
 lemma scast_down_minus:
     "is_down (scast:: 'a word \<Rightarrow> 'b word) \<Longrightarrow>  scast ((a :: 'a::len word) - b) = (scast a - scast b :: 'b::len word)"
   apply (rule scast_distrib [where L="(-)"], (clarsimp simp: uint_word_ariths)+)
   apply (metis mod_diff_left_eq mod_diff_right_eq)
   apply simp
   done
 
 lemma scast_down_mult:
     "is_down (scast:: 'a word \<Rightarrow> 'b word) \<Longrightarrow>  scast ((a :: 'a::len word) * b) = (scast a * scast b :: 'b::len word)"
   apply (rule scast_distrib [where L="(*)"], (clarsimp simp: uint_word_ariths)+)
   apply (metis mod_mult_eq)
   apply simp
   done
 
 lemma scast_ucast_1:
   "\<lbrakk> is_down (ucast :: 'a word \<Rightarrow> 'b word); is_down (ucast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
          (scast (ucast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = ucast a"
   by (metis down_cast_same ucast_eq ucast_down_wi)
 
 lemma scast_ucast_3:
   "\<lbrakk> is_down (ucast :: 'a word \<Rightarrow> 'c word); is_down (ucast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
          (scast (ucast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = ucast a"
   by (metis down_cast_same ucast_eq ucast_down_wi)
 
 lemma scast_ucast_4:
   "\<lbrakk> is_up (ucast :: 'a word \<Rightarrow> 'b word); is_down (ucast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
          (scast (ucast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = ucast a"
   by (metis down_cast_same ucast_eq ucast_down_wi)
 
 lemma scast_scast_b:
   "\<lbrakk> is_up (scast :: 'a word \<Rightarrow> 'b word) \<rbrakk> \<Longrightarrow>
      (scast (scast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = scast a"
   by (metis scast_eq sint_up_scast)
 
 lemma ucast_scast_1:
   "\<lbrakk> is_down (scast :: 'a word \<Rightarrow> 'b word); is_down (ucast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
             (ucast (scast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = scast a"
   by (metis scast_eq ucast_down_wi)
 
 lemma ucast_scast_3:
   "\<lbrakk> is_down (scast :: 'a word \<Rightarrow> 'c word); is_down (ucast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
      (ucast (scast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = scast a"
   by (metis scast_eq ucast_down_wi)
 
 lemma ucast_scast_4:
   "\<lbrakk> is_up (scast :: 'a word \<Rightarrow> 'b word); is_down (ucast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
      (ucast (scast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = scast a"
   by (metis down_cast_same scast_eq sint_up_scast)
 
 lemma ucast_ucast_a:
   "\<lbrakk> is_down (ucast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
         (ucast (ucast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = ucast a"
   by (metis down_cast_same ucast_eq ucast_down_wi)
 
 lemma ucast_ucast_b:
   "\<lbrakk> is_up (ucast :: 'a word \<Rightarrow> 'b word) \<rbrakk> \<Longrightarrow>
      (ucast (ucast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = ucast a"
   by (metis ucast_up_ucast)
 
 lemma scast_scast_a:
   "\<lbrakk> is_down (scast :: 'b word \<Rightarrow> 'c word) \<rbrakk> \<Longrightarrow>
             (scast (scast (a :: 'a::len word) :: 'b::len word) :: 'c::len word) = scast a"
   apply (simp only: scast_eq)
   apply (metis down_cast_same is_up_down scast_eq ucast_down_wi)
   done
 
 lemma scast_down_wi [OF refl]:
   "uc = scast \<Longrightarrow> is_down uc \<Longrightarrow> uc (word_of_int x) = word_of_int x"
   by (metis down_cast_same is_up_down ucast_down_wi)
 
 lemmas cast_simps =
   is_down is_up
   scast_down_add scast_down_minus scast_down_mult
   ucast_down_add ucast_down_minus ucast_down_mult
   scast_ucast_1 scast_ucast_3 scast_ucast_4
   ucast_scast_1 ucast_scast_3 ucast_scast_4
   ucast_ucast_a ucast_ucast_b
   scast_scast_a scast_scast_b
   ucast_down_bl
   ucast_down_wi scast_down_wi
   ucast_of_nat scast_of_nat
   uint_up_ucast sint_up_scast
   up_scast_surj up_ucast_surj
 
 lemma smod_mod_positive:
     "\<lbrakk> 0 \<le> (a :: int); 0 \<le> b \<rbrakk> \<Longrightarrow> a smod b = a mod b"
   by (clarsimp simp: smod_int_alt_def zsgn_def)
 
 lemma nat_mult_power_less_eq:
   "b > 0 \<Longrightarrow> (a * b ^ n < (b :: nat) ^ m) = (a < b ^ (m - n))"
   using mult_less_cancel2[where m = a and k = "b ^ n" and n="b ^ (m - n)"]
         mult_less_cancel2[where m="a * b ^ (n - m)" and k="b ^ m" and n=1]
   apply (simp only: power_add[symmetric] nat_minus_add_max)
   apply (simp only: power_add[symmetric] nat_minus_add_max ac_simps)
   apply (simp add: max_def split: if_split_asm)
   done
 
 lemma signed_shift_guard_to_word:
   "\<lbrakk> n < len_of TYPE ('a); n > 0 \<rbrakk>
     \<Longrightarrow> (unat (x :: 'a :: len word) * 2 ^ y < 2 ^ n)
     = (x = 0 \<or> x < (1 << n >> y))"
   apply (simp only: nat_mult_power_less_eq)
   apply (cases "y \<le> n")
    apply (simp only: shiftl_shiftr1)
    apply (subst less_mask_eq)
     apply (simp add: word_less_nat_alt word_size)
     apply (rule order_less_le_trans[rotated], rule power_increasing[where n=1])
       apply simp
      apply simp
     apply simp
    apply (simp add: nat_mult_power_less_eq word_less_nat_alt word_size)
    apply auto[1]
   apply (simp only: shiftl_shiftr2, simp add: unat_eq_0)
   done
 
 lemma sint_ucast_eq_uint:
     "\<lbrakk> \<not> is_down (ucast :: ('a::len word \<Rightarrow> 'b::len word)) \<rbrakk>
             \<Longrightarrow> sint ((ucast :: ('a::len word \<Rightarrow> 'b::len word)) x) = uint x"
   apply (subst sint_eq_uint)
    apply (simp add: msb_word_eq)
    apply transfer
    apply (simp add: bit_take_bit_iff)
   apply transfer
   apply simp
   done
 
 lemma word_less_nowrapI':
   "(x :: 'a :: len word) \<le> z - k \<Longrightarrow> k \<le> z \<Longrightarrow> 0 < k \<Longrightarrow> x < x + k"
   by uint_arith
 
 lemma mask_plus_1:
   "mask n + 1 = (2 ^ n :: 'a::len word)"
   by (clarsimp simp: mask_eq_decr_exp)
 
 lemma unat_inj: "inj unat"
   by (metis eq_iff injI word_le_nat_alt)
 
 lemma unat_ucast_upcast:
   "is_up (ucast :: 'b word \<Rightarrow> 'a word)
       \<Longrightarrow> unat (ucast x :: ('a::len) word) = unat (x :: ('b::len) word)"
   unfolding ucast_eq unat_eq_nat_uint
   apply (subst int_word_uint)
   apply (subst mod_pos_pos_trivial)
     apply simp
    apply (rule lt2p_lem)
    apply (clarsimp simp: is_up)
   apply simp
   done
 
 lemma ucast_mono:
   "\<lbrakk> (x :: 'b :: len word) < y; y < 2 ^ LENGTH('a) \<rbrakk>
    \<Longrightarrow> ucast x < ((ucast y) :: 'a :: len word)"
   apply (simp only: flip: ucast_nat_def)
   apply (rule of_nat_mono_maybe)
   apply (rule unat_less_helper)
   apply (simp add: Power.of_nat_power)
   apply (simp add: word_less_nat_alt)
   done
 
 lemma ucast_mono_le:
   "\<lbrakk>x \<le> y; y < 2 ^ LENGTH('b)\<rbrakk> \<Longrightarrow> (ucast (x :: 'a :: len word) :: 'b :: len word) \<le> ucast y"
   apply (simp only: flip: ucast_nat_def)
   apply (subst of_nat_mono_maybe_le[symmetric])
     apply (rule unat_less_helper)
     apply (simp add: Power.of_nat_power)
    apply (rule unat_less_helper)
    apply (erule le_less_trans)
    apply (simp add: Power.of_nat_power)
   apply (simp add: word_le_nat_alt)
   done
 
 lemma ucast_mono_le':
   "\<lbrakk> unat y < 2 ^ LENGTH('b); LENGTH('b::len) < LENGTH('a::len); x \<le> y \<rbrakk>
    \<Longrightarrow> UCAST('a \<rightarrow> 'b) x \<le> UCAST('a \<rightarrow> 'b) y"
   by (auto simp: word_less_nat_alt intro: ucast_mono_le)
 
 lemma zero_sle_ucast_up:
   "\<not> is_down (ucast :: 'a word \<Rightarrow> 'b signed word) \<Longrightarrow>
           (0 <=s ((ucast (b::('a::len) word)) :: ('b::len) signed word))"
   apply (subgoal_tac "\<not> msb (ucast b :: 'b signed word)")
    apply (clarsimp simp: word_sle_msb_le)
   apply (clarsimp simp: is_down not_le msb_nth nth_ucast)
   done
 
 lemma word_le_ucast_sless:
   "\<lbrakk> x \<le> y; y \<noteq> -1; LENGTH('a) < LENGTH('b) \<rbrakk> \<Longrightarrow>
     UCAST (('a :: len) \<rightarrow> ('b :: len) signed) x <s ucast (y + 1)"
   by (clarsimp simp: word_le_make_less word_sless_alt sint_ucast_eq_uint is_down word_less_def)
 
 lemma msb_ucast_eq:
     "LENGTH('a) = LENGTH('b) \<Longrightarrow>
          msb (ucast x :: ('a::len) word) = msb (x :: ('b::len) word)"
   apply (clarsimp simp: word_msb_alt)
   apply (subst ucast_down_drop [where n=0])
    apply (clarsimp simp: source_size_def target_size_def word_size)
   apply clarsimp
   done
 
 lemma msb_big:
      "msb (a :: ('a::len) word) = (a \<ge> 2 ^ (LENGTH('a)  - Suc 0))"
   apply (rule iffI)
    apply (clarsimp simp: msb_nth)
    apply (drule bang_is_le)
    apply simp
   apply (rule ccontr)
   apply (subgoal_tac "a = a && mask (LENGTH('a) - Suc 0)")
    apply (cut_tac and_mask_less' [where w=a and n="LENGTH('a) - Suc 0"])
     apply (clarsimp simp: word_not_le [symmetric])
    apply clarsimp
   apply (rule sym, subst and_mask_eq_iff_shiftr_0)
   apply (clarsimp simp: msb_shift)
   done
 
 lemma zero_sle_ucast:
   "(0 <=s ((ucast (b::('a::len) word)) :: ('a::len) signed word))
                 = (uint b < 2 ^ (LENGTH('a) - 1))"
   apply (case_tac "msb b")
    apply (clarsimp simp: word_sle_msb_le not_less msb_ucast_eq del: notI)
    apply (clarsimp simp: msb_big word_le_def uint_2p_alt)
   apply (clarsimp simp: word_sle_msb_le not_less msb_ucast_eq del: notI)
   apply (clarsimp simp: msb_big word_le_def uint_2p_alt)
   done
 
 
 (* to_bool / from_bool. *)
 
 definition
   from_bool :: "bool \<Rightarrow> 'a::len word" where
   "from_bool b \<equiv> case b of True \<Rightarrow> of_nat 1
                          | False \<Rightarrow> of_nat 0"
 
 lemma from_bool_eq:
   \<open>from_bool = of_bool\<close>
   by (simp add: fun_eq_iff from_bool_def)
 
 lemma from_bool_0:
   "(from_bool x = 0) = (\<not> x)"
   by (simp add: from_bool_def split: bool.split)
 
 definition
   to_bool :: "'a::len word \<Rightarrow> bool" where
   "to_bool \<equiv> (\<noteq>) 0"
 
 lemma to_bool_and_1:
   "to_bool (x && 1) = (x !! 0)"
   by (simp add: test_bit_word_eq to_bool_def and_one_eq mod_2_eq_odd)
 
 lemma to_bool_from_bool [simp]:
   "to_bool (from_bool r) = r"
   unfolding from_bool_def to_bool_def
   by (simp split: bool.splits)
 
 lemma from_bool_neq_0 [simp]:
   "(from_bool b \<noteq> 0) = b"
   by (simp add: from_bool_def split: bool.splits)
 
 lemma from_bool_mask_simp [simp]:
   "(from_bool r :: 'a::len word) && 1 = from_bool r"
   unfolding from_bool_def
   by (clarsimp split: bool.splits)
 
 lemma from_bool_1 [simp]:
   "(from_bool P = 1) = P"
   by (simp add: from_bool_def split: bool.splits)
 
 lemma ge_0_from_bool [simp]:
   "(0 < from_bool P) = P"
   by (simp add: from_bool_def split: bool.splits)
 
 lemma limited_and_from_bool:
   "limited_and (from_bool b) 1"
   by (simp add: from_bool_def limited_and_def split: bool.split)
 
 lemma to_bool_1 [simp]: "to_bool 1" by (simp add: to_bool_def)
 lemma to_bool_0 [simp]: "\<not>to_bool 0" by (simp add: to_bool_def)
 
 lemma from_bool_eq_if:
   "(from_bool Q = (if P then 1 else 0)) = (P = Q)"
   by (simp add: case_bool_If from_bool_def split: if_split)
 
 lemma to_bool_eq_0:
   "(\<not> to_bool x) = (x = 0)"
   by (simp add: to_bool_def)
 
 lemma to_bool_neq_0:
   "(to_bool x) = (x \<noteq> 0)"
   by (simp add: to_bool_def)
 
 lemma from_bool_all_helper:
   "(\<forall>bool. from_bool bool = val \<longrightarrow> P bool)
       = ((\<exists>bool. from_bool bool = val) \<longrightarrow> P (val \<noteq> 0))"
   by (auto simp: from_bool_0)
 
 lemma from_bool_to_bool_iff:
   "w = from_bool b \<longleftrightarrow> to_bool w = b \<and> (w = 0 \<or> w = 1)"
   by (cases b) (auto simp: from_bool_def to_bool_def)
 
 lemma from_bool_eqI:
   "from_bool x = from_bool y \<Longrightarrow> x = y"
   unfolding from_bool_def
   by (auto split: bool.splits)
 
 lemma word_rsplit_upt:
   "\<lbrakk> size x = LENGTH('a :: len) * n; n \<noteq> 0 \<rbrakk>
     \<Longrightarrow> word_rsplit x = map (\<lambda>i. ucast (x >> i * len_of TYPE ('a)) :: 'a word) (rev [0 ..< n])"
   apply (subgoal_tac "length (word_rsplit x :: 'a word list) = n")
    apply (rule nth_equalityI, simp)
    apply (intro allI word_eqI impI)
    apply (simp add: test_bit_rsplit_alt word_size)
    apply (simp add: nth_ucast nth_shiftr rev_nth field_simps)
   apply (simp add: length_word_rsplit_exp_size)
   apply (metis mult.commute given_quot_alt word_size word_size_gt_0)
   done
 
 lemma aligned_shift:
   "\<lbrakk>x < 2 ^ n; is_aligned (y :: 'a :: len word) n;n \<le> LENGTH('a)\<rbrakk>
    \<Longrightarrow> x + y >> n = y >> n"
   by (subst word_plus_and_or_coroll; word_eqI, blast)
 
 lemma aligned_shift':
   "\<lbrakk>x < 2 ^ n; is_aligned (y :: 'a :: len word) n;n \<le> LENGTH('a)\<rbrakk>
    \<Longrightarrow> y + x >> n = y >> n"
   by (subst word_plus_and_or_coroll; word_eqI, blast)
 
 lemma neg_mask_add_mask:
   "((x:: 'a :: len word) && ~~ (mask n)) + (2 ^ n - 1) = x || mask n"
   unfolding mask_2pm1[symmetric]
   by (subst word_plus_and_or_coroll; word_eqI_solve)
 
 lemma subtract_mask:
   "p - (p && mask n) = (p && ~~ (mask n))"
   "p - (p && ~~ (mask n)) = (p && mask n)"
   by (simp add: field_simps word_plus_and_or_coroll2)+
 
 lemma and_neg_mask_plus_mask_mono: "(p && ~~ (mask n)) + mask n \<ge> p"
   apply (rule word_le_minus_cancel[where x = "p && ~~ (mask n)"])
    apply (clarsimp simp: subtract_mask)
    using word_and_le1[where a = "mask n" and y = p]
    apply (clarsimp simp: mask_eq_decr_exp word_le_less_eq)
   apply (rule is_aligned_no_overflow'[folded mask_2pm1])
   apply (clarsimp simp: is_aligned_neg_mask)
   done
 
 lemma word_neg_and_le:
   "ptr \<le> (ptr && ~~ (mask n)) + (2 ^ n - 1)"
   by (simp add: and_neg_mask_plus_mask_mono mask_2pm1[symmetric])
 
 lemma aligned_less_plus_1:
   "\<lbrakk> is_aligned x n; n > 0 \<rbrakk> \<Longrightarrow> x < x + 1"
   apply (rule plus_one_helper2)
    apply (rule order_refl)
   apply (clarsimp simp: field_simps)
   apply (drule arg_cong[where f="\<lambda>x. x - 1"])
   apply (clarsimp simp: is_aligned_mask)
   apply (drule word_eqD[where x=0])
   apply simp
   done
 
 lemma aligned_add_offset_less:
   "\<lbrakk>is_aligned x n; is_aligned y n; x < y; z < 2 ^ n\<rbrakk> \<Longrightarrow> x + z < y"
   apply (cases "y = 0")
    apply simp
   apply (erule is_aligned_get_word_bits[where p=y], simp_all)
   apply (cases "z = 0", simp_all)
   apply (drule(2) aligned_at_least_t2n_diff[rotated -1])
   apply (drule plus_one_helper2)
    apply (rule less_is_non_zero_p1)
    apply (rule aligned_less_plus_1)
     apply (erule aligned_sub_aligned[OF _ _ order_refl],
            simp_all add: is_aligned_triv)[1]
    apply (cases n, simp_all)[1]
   apply (simp only: trans[OF diff_add_eq diff_diff_eq2[symmetric]])
   apply (drule word_less_add_right)
    apply (rule ccontr, simp add: linorder_not_le)
    apply (drule aligned_small_is_0, erule order_less_trans)
     apply (clarsimp simp: power_overflow)
    apply simp
   apply (erule order_le_less_trans[rotated],
          rule word_plus_mono_right)
    apply (erule word_le_minus_one_leq)
   apply (simp add: is_aligned_no_wrap' is_aligned_no_overflow field_simps)
   done
 
 lemma is_aligned_add_helper:
   "\<lbrakk> is_aligned p n; d < 2 ^ n \<rbrakk>
      \<Longrightarrow> (p + d && mask n = d) \<and> (p + d && (~~ (mask n)) = p)"
   apply (subst(asm) is_aligned_mask)
   apply (drule less_mask_eq)
   apply (rule context_conjI)
    apply (subst word_plus_and_or_coroll; word_eqI; blast)
   using word_plus_and_or_coroll2[where x="p + d" and w="mask n"] by simp
 
 lemma is_aligned_sub_helper:
   "\<lbrakk> is_aligned (p - d) n; d < 2 ^ n \<rbrakk>
      \<Longrightarrow> (p && mask n = d) \<and> (p && (~~ (mask n)) = p - d)"
   by (drule(1) is_aligned_add_helper, simp)
 
 lemma mask_twice:
   "(x && mask n) && mask m = x && mask (min m n)"
   by word_eqI_solve
 
 lemma is_aligned_after_mask:
   "\<lbrakk>is_aligned k m;m\<le> n\<rbrakk> \<Longrightarrow> is_aligned (k && mask n) m"
   by (rule is_aligned_andI1)
 
 lemma and_mask_plus:
   "\<lbrakk>is_aligned ptr m; m \<le> n; a < 2 ^ m\<rbrakk>
    \<Longrightarrow> ptr + a && mask n = (ptr && mask n) + a"
   apply (rule mask_eqI[where n = m])
    apply (simp add:mask_twice min_def)
     apply (simp add:is_aligned_add_helper)
     apply (subst is_aligned_add_helper[THEN conjunct1])
       apply (erule is_aligned_after_mask)
      apply simp
     apply simp
    apply simp
   apply (subgoal_tac "(ptr + a && mask n) && ~~ (mask m)
      = (ptr + a && ~~ (mask m) ) && mask n")
    apply (simp add:is_aligned_add_helper)
    apply (subst is_aligned_add_helper[THEN conjunct2])
      apply (simp add:is_aligned_after_mask)
     apply simp
    apply simp
   apply (simp add:word_bw_comms word_bw_lcs)
   done
 
 lemma le_step_down_word:"\<lbrakk>(i::('a::len) word) \<le> n; i = n \<longrightarrow> P; i \<le> n - 1 \<longrightarrow> P\<rbrakk> \<Longrightarrow> P"
   by unat_arith
 
 lemma le_step_down_word_2:
   fixes x :: "'a::len word"
   shows "\<lbrakk>x \<le>  y; x \<noteq> y\<rbrakk> \<Longrightarrow> x \<le> y - 1"
   by (subst (asm) word_le_less_eq,
       clarsimp,
       simp add: word_le_minus_one_leq)
 
 lemma NOT_mask_AND_mask[simp]: "(w && mask n) && ~~ (mask n) = 0"
   by (clarsimp simp add: mask_eq_decr_exp Parity.bit_eq_iff bit_and_iff bit_not_iff bit_mask_iff)
 
 lemma and_and_not[simp]:"(a && b) && ~~ b = 0"
   apply (subst word_bw_assocs(1))
   apply clarsimp
   done
 
 lemma mask_shift_and_negate[simp]:"(w && mask n << m) && ~~ (mask n << m) = 0"
   by (clarsimp simp add: mask_eq_decr_exp Parity.bit_eq_iff bit_and_iff bit_not_iff shiftl_word_eq bit_push_bit_iff)
 
 lemma le_step_down_nat:"\<lbrakk>(i::nat) \<le> n; i = n \<longrightarrow> P; i \<le> n - 1 \<longrightarrow> P\<rbrakk> \<Longrightarrow> P"
   by arith
 
 lemma le_step_down_int:"\<lbrakk>(i::int) \<le> n; i = n \<longrightarrow> P; i \<le> n - 1 \<longrightarrow> P\<rbrakk> \<Longrightarrow> P"
   by arith
 
 lemma ex_mask_1[simp]: "(\<exists>x. mask x = (1 :: 'a::len word))"
   apply (rule_tac x=1 in exI)
   apply (simp add:mask_eq_decr_exp)
   done
 
 lemma not_switch:"~~ a = x \<Longrightarrow> a = ~~ x"
   by auto
 
 (* The seL4 bitfield generator produces functions containing mask and shift operations, such that
  * invoking two of them consecutively can produce something like the following.
  *)
 lemma bitfield_op_twice:
   "(x && ~~ (mask n << m) || ((y && mask n) << m)) && ~~ (mask n << m) = x && ~~ (mask n << m)"
   by (induct n arbitrary: m) (auto simp: word_ao_dist)
 
 lemma bitfield_op_twice'':
   "\<lbrakk>~~ a = b << c; \<exists>x. b = mask x\<rbrakk> \<Longrightarrow> (x && a || (y && b << c)) && a = x && a"
   apply clarsimp
   apply (cut_tac n=xa and m=c and x=x and y=y in bitfield_op_twice)
   apply (clarsimp simp:mask_eq_decr_exp)
   apply (drule not_switch)
   apply clarsimp
   done
 
 lemma bit_twiddle_min:
   "(y::'a::len word) xor (((x::'a::len word) xor y) && (if x < y then -1 else 0)) = min x y"
   by (auto simp add: Parity.bit_eq_iff bit_xor_iff min_def)
 
 lemma bit_twiddle_max:
   "(x::'a::len word) xor (((x::'a::len word) xor y) && (if x < y then -1 else 0)) = max x y"
   by (auto simp add: Parity.bit_eq_iff bit_xor_iff max_def)
 
 lemma swap_with_xor:
   "\<lbrakk>(x::'a::len word) = a xor b; y = b xor x; z = x xor y\<rbrakk> \<Longrightarrow> z = b \<and> y = a"
   by (auto simp add: Parity.bit_eq_iff bit_xor_iff max_def)
 
 lemma scast_nop1 [simp]:
   "((scast ((of_int x)::('a::len) word))::'a sword) = of_int x"
   apply (simp only: scast_eq)
   by (metis len_signed sint_sbintrunc' word_sint.Rep_inverse)
 
 lemma scast_nop2 [simp]:
   "((scast ((of_int x)::('a::len) sword))::'a word) = of_int x"
   apply (simp only: scast_eq)
   by (metis len_signed sint_sbintrunc' word_sint.Rep_inverse)
 
 lemmas scast_nop = scast_nop1 scast_nop2 scast_id
 
 lemma le_mask_imp_and_mask:
   "(x::'a::len word) \<le> mask n \<Longrightarrow> x && mask n = x"
   by (metis and_mask_eq_iff_le_mask)
 
 lemma or_not_mask_nop:
   "((x::'a::len word) || ~~ (mask n)) && mask n = x && mask n"
   by (metis word_and_not word_ao_dist2 word_bw_comms(1) word_log_esimps(3))
 
 lemma mask_subsume:
   "\<lbrakk>n \<le> m\<rbrakk> \<Longrightarrow> ((x::'a::len word) || y && mask n) && ~~ (mask m) = x && ~~ (mask m)"
   by (auto simp add: Parity.bit_eq_iff bit_not_iff bit_or_iff bit_and_iff bit_mask_iff)
 
 lemma and_mask_0_iff_le_mask:
   fixes w :: "'a::len word"
   shows "(w && ~~(mask n) = 0) = (w \<le> mask n)"
   by (simp add: mask_eq_0_eq_x le_mask_imp_and_mask and_mask_eq_iff_le_mask)
 
 lemma mask_twice2:
   "n \<le> m \<Longrightarrow> ((x::'a::len word) && mask m) && mask n = x && mask n"
   by (metis mask_twice min_def)
 
 lemma uint_2_id:
   "LENGTH('a) \<ge> 2 \<Longrightarrow> uint (2::('a::len) word) = 2"
   by simp
 
 lemma bintrunc_id:
   "\<lbrakk>m \<le> of_nat n; 0 < m\<rbrakk> \<Longrightarrow> bintrunc n m = m"
   by (simp add: bintrunc_mod2p le_less_trans)
 
 lemma shiftr1_unfold: "shiftr1 x = x >> 1"
   by (metis One_nat_def comp_apply funpow.simps(1) funpow.simps(2) id_apply shiftr_def)
 
 lemma shiftr1_is_div_2: "(x::('a::len) word) >> 1 = x div 2"
   by transfer (simp add: drop_bit_Suc)
 
 lemma shiftl1_is_mult: "(x << 1) = (x :: 'a::len word) * 2"
   by (metis One_nat_def mult_2 mult_2_right one_add_one
         power_0 power_Suc shiftl_t2n)
 
 lemma div_of_0_id[simp]:"(0::('a::len) word) div n = 0"
   by (simp add: word_div_def)
 
 lemma degenerate_word:"LENGTH('a) = 1 \<Longrightarrow> (x::('a::len) word) = 0 \<or> x = 1"
   by (metis One_nat_def less_irrefl_nat sint_1_cases)
 
 lemma div_by_0_word:"(x::('a::len) word) div 0 = 0"
   by (metis div_0 div_by_0 unat_0 word_arith_nat_defs(6) word_div_1)
 
 lemma div_less_dividend_word:"\<lbrakk>x \<noteq> 0; n \<noteq> 1\<rbrakk> \<Longrightarrow> (x::('a::len) word) div n < x"
   apply (cases \<open>n = 0\<close>)
    apply clarsimp
    apply (simp add:word_neq_0_conv)
   apply (subst word_arith_nat_div)
   apply (rule word_of_nat_less)
   apply (rule div_less_dividend)
   using unat_eq_zero word_unat_Rep_inject1 apply force
   apply (simp add:unat_gt_0)
   done
 
 lemma shiftr1_lt:"x \<noteq> 0 \<Longrightarrow> (x::('a::len) word) >> 1 < x"
   apply (subst shiftr1_is_div_2)
   apply (rule div_less_dividend_word)
    apply simp+
   done
 
 lemma word_less_div:
   fixes x :: "('a::len) word"
     and y :: "('a::len) word"
   shows "x div y = 0 \<Longrightarrow> y = 0 \<or> x < y"
   apply (case_tac "y = 0", clarsimp+)
   by (metis One_nat_def Suc_le_mono le0 le_div_geq not_less unat_0 unat_div unat_gt_0 word_less_nat_alt zero_less_one)
 
 lemma not_degenerate_imp_2_neq_0:"LENGTH('a) > 1 \<Longrightarrow> (2::('a::len) word) \<noteq> 0"
   by (metis numerals(1) power_not_zero power_zero_numeral)
 
 lemma shiftr1_0_or_1:"(x::('a::len) word) >> 1 = 0 \<Longrightarrow> x = 0 \<or> x = 1"
   apply (subst (asm) shiftr1_is_div_2)
   apply (drule word_less_div)
   apply (case_tac "LENGTH('a) = 1")
    apply (simp add:degenerate_word)
   apply (erule disjE)
    apply (subgoal_tac "(2::'a word) \<noteq> 0")
     apply simp
    apply (rule not_degenerate_imp_2_neq_0)
    apply (subgoal_tac "LENGTH('a) \<noteq> 0")
     apply arith
    apply simp
   apply (rule x_less_2_0_1', simp+)
   done
 
 lemma word_overflow:"(x::('a::len) word) + 1 > x \<or> x + 1 = 0"
   apply clarsimp
   by (metis diff_0 eq_diff_eq less_x_plus_1)
 
 lemma word_overflow_unat:"unat ((x::('a::len) word) + 1) = unat x + 1 \<or> x + 1 = 0"
   by (metis Suc_eq_plus1 add.commute unatSuc)
 
 lemma even_word_imp_odd_next:"even (unat (x::('a::len) word)) \<Longrightarrow> x + 1 = 0 \<or> odd (unat (x + 1))"
   apply (cut_tac x=x in word_overflow_unat)
   apply clarsimp
   done
 
 lemma odd_word_imp_even_next:"odd (unat (x::('a::len) word)) \<Longrightarrow> x + 1 = 0 \<or> even (unat (x + 1))"
   apply (cut_tac x=x in word_overflow_unat)
   apply clarsimp
   done
 
 lemma overflow_imp_lsb:"(x::('a::len) word) + 1 = 0 \<Longrightarrow> x !! 0"
   using even_plus_one_iff [of x] by (simp add: test_bit_word_eq)
 
 lemma word_lsb_nat:"lsb w = (unat w mod 2 = 1)"
   apply (simp add: word_lsb_def Groebner_Basis.algebra(31))
   apply transfer
   apply (simp add: even_nat_iff)
   done
 
 lemma odd_iff_lsb:"odd (unat (x::('a::len) word)) = x !! 0"
   apply (simp add:even_iff_mod_2_eq_zero)
   apply (subst word_lsb_nat[unfolded One_nat_def, symmetric])
   apply (rule word_lsb_alt)
   done
 
 lemma of_nat_neq_iff_word:
       "x mod 2 ^ LENGTH('a) \<noteq> y mod 2 ^ LENGTH('a) \<Longrightarrow>
          (((of_nat x)::('a::len) word) \<noteq> of_nat y) = (x \<noteq> y)"
   apply (rule iffI)
    apply (case_tac "x = y")
    apply (subst (asm) of_nat_eq_iff[symmetric])
    apply simp+
   apply (case_tac "((of_nat x)::('a::len) word) = of_nat y")
    apply (subst (asm) word_unat.norm_eq_iff[symmetric])
    apply simp+
   done
 
 lemma shiftr1_irrelevant_lsb:"(x::('a::len) word) !! 0 \<or> x >> 1 = (x + 1) >> 1"
   using word_overflow_unat [of x]
   apply (simp only: shiftr1_is_div_2 flip: odd_iff_lsb)
   apply (cases \<open>2 \<le> LENGTH('a)\<close>)
    apply (auto simp add: test_bit_def' word_arith_nat_div dest: overflow_imp_lsb)
   using odd_iff_lsb overflow_imp_lsb by blast
 
 lemma shiftr1_0_imp_only_lsb:"((x::('a::len) word) + 1) >> 1 = 0 \<Longrightarrow> x = 0 \<or> x + 1 = 0"
   by (metis One_nat_def shiftr1_0_or_1 word_less_1 word_overflow)
 
 lemma shiftr1_irrelevant_lsb':"\<not>((x::('a::len) word) !! 0) \<Longrightarrow> x >> 1 = (x + 1) >> 1"
   by (metis shiftr1_irrelevant_lsb)
 
 lemma lsb_this_or_next:"\<not>(((x::('a::len) word) + 1) !! 0) \<Longrightarrow> x !! 0"
   by (metis (poly_guards_query) even_word_imp_odd_next odd_iff_lsb overflow_imp_lsb)
 
 (* Perhaps this one should be a simp lemma, but it seems a little dangerous. *)
 lemma cast_chunk_assemble_id:
   "\<lbrakk>n = LENGTH('a::len); m = LENGTH('b::len); n * 2 = m\<rbrakk> \<Longrightarrow>
   (((ucast ((ucast (x::'b word))::'a word))::'b word) || (((ucast ((ucast (x >> n))::'a word))::'b word) << n)) = x"
   apply (subgoal_tac "((ucast ((ucast (x >> n))::'a word))::'b word) = x >> n")
    apply clarsimp
    apply (subst and_not_mask[symmetric])
    apply (subst ucast_ucast_mask)
    apply (subst word_ao_dist2[symmetric])
    apply clarsimp
   apply (rule ucast_ucast_len)
   apply (rule shiftr_less_t2n')
    apply (subst and_mask_eq_iff_le_mask)
    apply (simp_all add: mask_eq_decr_exp flip: mult_2_right)
   apply (metis add_diff_cancel_left' len_gt_0 mult_2_right zero_less_diff)
   done
 
 lemma cast_chunk_scast_assemble_id:
   "\<lbrakk>n = LENGTH('a::len); m = LENGTH('b::len); n * 2 = m\<rbrakk> \<Longrightarrow>
   (((ucast ((scast (x::'b word))::'a word))::'b word) ||
    (((ucast ((scast (x >> n))::'a word))::'b word) << n)) = x"
   apply (subgoal_tac "((scast x)::'a word) = ((ucast x)::'a word)")
    apply (subgoal_tac "((scast (x >> n))::'a word) = ((ucast (x >> n))::'a word)")
     apply (simp add:cast_chunk_assemble_id)
    apply (subst down_cast_same[symmetric], subst is_down, arith, simp)+
   done
 
 lemma mask_or_not_mask:
   "x && mask n || x && ~~ (mask n) = x"
   apply (subst word_oa_dist, simp)
   apply (subst word_oa_dist2, simp)
   done
 
 lemma is_aligned_add_not_aligned:
   "\<lbrakk>is_aligned (p::'a::len word) n; \<not> is_aligned (q::'a::len word) n\<rbrakk> \<Longrightarrow> \<not> is_aligned (p + q) n"
   by (metis is_aligned_addD1)
 
 lemma word_gr0_conv_Suc: "(m::'a::len word) > 0 \<Longrightarrow> \<exists>n. m = n + 1"
   by (metis add.commute add_minus_cancel)
 
 lemma neg_mask_add_aligned:
   "\<lbrakk> is_aligned p n; q < 2 ^ n \<rbrakk> \<Longrightarrow> (p + q) && ~~ (mask n) = p && ~~ (mask n)"
   by (metis is_aligned_add_helper is_aligned_neg_mask_eq)
 
 lemma word_sless_sint_le:"x <s y \<Longrightarrow> sint x \<le> sint y - 1"
   by (metis word_sless_alt zle_diff1_eq)
 
 
 lemma upper_trivial:
   fixes x :: "'a::len word"
   shows "x \<noteq> 2 ^ LENGTH('a) - 1 \<Longrightarrow> x < 2 ^ LENGTH('a) - 1"
   by (simp add: less_le)
 
 lemma constraint_expand:
   fixes x :: "'a::len word"
   shows "x \<in> {y. lower \<le> y \<and> y \<le> upper} = (lower \<le> x \<and> x \<le> upper)"
   by (rule mem_Collect_eq)
 
 lemma card_map_elide:
   "card ((of_nat :: nat \<Rightarrow> 'a::len word) ` {0..<n}) = card {0..<n}"
     if "n \<le> CARD('a::len word)"
 proof -
   let ?of_nat = "of_nat :: nat \<Rightarrow> 'a word"
   from word_unat.Abs_inj_on
   have "inj_on ?of_nat {i. i < CARD('a word)}"
     by (simp add: unats_def card_word)
   moreover have "{0..<n} \<subseteq> {i. i < CARD('a word)}"
     using that by auto
   ultimately have "inj_on ?of_nat {0..<n}"
     by (rule inj_on_subset)
   then show ?thesis
     by (simp add: card_image)
 qed
 
 lemma card_map_elide2:
   "n \<le> CARD('a::len word) \<Longrightarrow> card ((of_nat::nat \<Rightarrow> 'a::len word) ` {0..<n}) = n"
   by (subst card_map_elide) clarsimp+
 
 lemma le_max_word_ucast_id:
   \<open>UCAST('b \<rightarrow> 'a) (UCAST('a \<rightarrow> 'b) x) = x\<close>
     if \<open>x \<le> UCAST('b::len \<rightarrow> 'a) (- 1)\<close>
     for x :: \<open>'a::len word\<close>
 proof -
   from that have a1: \<open>x \<le> word_of_int (uint (word_of_int (2 ^ LENGTH('b) - 1) :: 'b word))\<close>
     by simp
   have f2: "((\<exists>i ia. (0::int) \<le> i \<and> \<not> 0 \<le> i + - 1 * ia \<and> i mod ia \<noteq> i) \<or>
             \<not> (0::int) \<le> - 1 + 2 ^ LENGTH('b) \<or> (0::int) \<le> - 1 + 2 ^ LENGTH('b) + - 1 * 2 ^ LENGTH('b) \<or>
             (- (1::int) + 2 ^ LENGTH('b)) mod 2 ^ LENGTH('b) =
               - 1 + 2 ^ LENGTH('b)) = ((\<exists>i ia. (0::int) \<le> i \<and> \<not> 0 \<le> i + - 1 * ia \<and> i mod ia \<noteq> i) \<or>
             \<not> (1::int) \<le> 2 ^ LENGTH('b) \<or>
             2 ^ LENGTH('b) + - (1::int) * ((- 1 + 2 ^ LENGTH('b)) mod 2 ^ LENGTH('b)) = 1)"
     by force
   have f3: "\<forall>i ia. \<not> (0::int) \<le> i \<or> 0 \<le> i + - 1 * ia \<or> i mod ia = i"
     using mod_pos_pos_trivial by force
   have "(1::int) \<le> 2 ^ LENGTH('b)"
     by simp
   then have "2 ^ LENGTH('b) + - (1::int) * ((- 1 + 2 ^ LENGTH('b)) mod 2 ^ len_of TYPE ('b)) = 1"
     using f3 f2 by blast
   then have f4: "- (1::int) + 2 ^ LENGTH('b) = (- 1 + 2 ^ LENGTH('b)) mod 2 ^ LENGTH('b)"
     by linarith
   have f5: "x \<le> word_of_int (uint (word_of_int (- 1 + 2 ^ LENGTH('b))::'b word))"
     using a1 by force
   have f6: "2 ^ LENGTH('b) + - (1::int) = - 1 + 2 ^ LENGTH('b)"
     by force
   have f7: "- (1::int) * 1 = - 1"
     by auto
   have "\<forall>x0 x1. (x1::int) - x0 = x1 + - 1 * x0"
     by force
   then have "x \<le> 2 ^ LENGTH('b) - 1"
     using f7 f6 f5 f4 by (metis uint_word_of_int wi_homs(2) word_arith_wis(8) word_of_int_2p)
   then have \<open>uint x \<le> uint (2 ^ LENGTH('b) - (1 :: 'a word))\<close>
     by (simp add: word_le_def)
   then have \<open>uint x \<le> 2 ^ LENGTH('b) - 1\<close>
     by (simp add: uint_word_ariths)
       (metis \<open>1 \<le> 2 ^ LENGTH('b)\<close> \<open>uint x \<le> uint (2 ^ LENGTH('b) - 1)\<close> linorder_not_less lt2p_lem uint_1 uint_minus_simple_alt uint_power_lower word_le_def zle_diff1_eq)
   then show ?thesis
     apply (simp add: word_ubin.eq_norm bintrunc_mod2p unsigned_ucast_eq)
     by (metis \<open>x \<le> 2 ^ LENGTH('b) - 1\<close> le_def take_bit_word_eq_self ucast_ucast_len unsigned_take_bit_eq word_less_sub_le word_ubin.norm_Rep word_uint_eqI)
 qed
 
 lemma remdups_enum_upto:
   fixes s::"'a::len word"
   shows "remdups [s .e. e] = [s .e. e]"
   by simp
 
 lemma card_enum_upto:
   fixes s::"'a::len word"
   shows "card (set [s .e. e]) = Suc (unat e) - unat s"
   by (subst List.card_set) (simp add: remdups_enum_upto)
 
 lemma unat_mask:
   "unat (mask n :: 'a :: len word) = 2 ^ (min n (LENGTH('a))) - 1"
   apply (subst min.commute)
   apply (simp add: mask_eq_decr_exp not_less min_def  split: if_split_asm)
   apply (intro conjI impI)
    apply (simp add: unat_sub_if_size)
    apply (simp add: power_overflow word_size)
   apply (simp add: unat_sub_if_size)
   done
 
 lemma word_shiftr_lt:
   fixes w :: "'a::len word"
   shows "unat (w >> n) < (2 ^ (LENGTH('a) - n))"
   apply (subst shiftr_div_2n')
   by (metis nat_mod_lem nat_zero_less_power_iff power_mod_div
       word_unat.Rep_inverse word_unat.eq_norm zero_less_numeral)
 
 lemma complement_nth_w2p:
   shows "n' < LENGTH('a) \<Longrightarrow> (~~ (2 ^ n :: 'a::len word)) !! n' = (n' \<noteq> n)"
   by (fastforce simp: word_ops_nth_size word_size nth_w2p)
 
 lemma word_unat_and_lt:
   "unat x < n \<or> unat y < n \<Longrightarrow> unat (x && y) < n"
   by (meson le_less_trans word_and_le1 word_and_le2 word_le_nat_alt)
 
 lemma word_unat_mask_lt:
   "m \<le> size w \<Longrightarrow> unat ((w::'a::len word) && mask m) < 2 ^ m"
   by (rule word_unat_and_lt) (simp add: unat_mask word_size)
 
 lemma unat_shiftr_less_t2n:
   fixes x :: "'a :: len word"
   shows "unat x < 2 ^ (n + m) \<Longrightarrow> unat (x >> n) < 2 ^ m"
   by (simp add: shiftr_div_2n' power_add mult.commute td_gal_lt)
 
 lemma le_or_mask:
   "w \<le> w' \<Longrightarrow> w || mask x \<le> w' || mask x"
   by (metis neg_mask_add_mask add.commute le_word_or1 mask_2pm1 neg_mask_mono_le word_plus_mono_left)
 
 lemma le_shiftr1':
   "\<lbrakk> shiftr1 u \<le> shiftr1 v ; shiftr1 u \<noteq> shiftr1 v \<rbrakk> \<Longrightarrow> u \<le> v"
   apply transfer
   apply simp
   done
 
 lemma le_shiftr':
   "\<lbrakk> u >> n \<le> v >> n ; u >> n \<noteq> v >> n \<rbrakk> \<Longrightarrow> (u::'a::len word) \<le> v"
   apply (induct n; simp add: shiftr_def)
   apply (case_tac "(shiftr1 ^^ n) u = (shiftr1 ^^ n) v", simp)
   apply (fastforce dest: le_shiftr1')
   done
 
 lemma word_log2_nth_same:
   "w \<noteq> 0 \<Longrightarrow> w !! word_log2 w"
   unfolding word_log2_def
   using nth_length_takeWhile[where P=Not and xs="to_bl w"]
   apply (simp add: word_clz_def word_size to_bl_nth)
   apply (fastforce simp: linorder_not_less eq_zero_set_bl
                    dest: takeWhile_take_has_property)
   done
 
 lemma word_log2_nth_not_set:
   "\<lbrakk> word_log2 w < i ; i < size w \<rbrakk> \<Longrightarrow> \<not> w !! i"
   unfolding word_log2_def word_clz_def
   using takeWhile_take_has_property_nth[where P=Not and xs="to_bl w" and n="size w - Suc i"]
   by (fastforce simp add: to_bl_nth word_size)
 
 lemma word_log2_highest:
   assumes a: "w !! i"
   shows "i \<le> word_log2 w"
 proof -
   from a have "i < size w" by - (rule test_bit_size)
   with a show ?thesis
     by - (rule ccontr, simp add: word_log2_nth_not_set)
 qed
 
 lemma word_log2_max:
   "word_log2 w < size w"
   unfolding word_log2_def word_clz_def
   by simp
 
 lemma word_clz_0[simp]:
   "word_clz (0::'a::len word) = LENGTH('a)"
   unfolding word_clz_def
   by (simp add: takeWhile_replicate)
 
 lemma word_clz_minus_one[simp]:
   "word_clz (-1::'a::len word) = 0"
   unfolding word_clz_def
   by (simp add: takeWhile_replicate)
 
 lemma word_add_no_overflow:"(x::'a::len word) < max_word \<Longrightarrow> x < x + 1"
   using less_x_plus_1 order_less_le by blast
 
 lemma lt_plus_1_le_word:
   fixes x :: "'a::len word"
   assumes bound:"n < unat (maxBound::'a word)"
   shows "x < 1 + of_nat n = (x \<le> of_nat n)"
   by (metis add.commute bound max_word_max word_Suc_leq word_not_le word_of_nat_less)
 
 lemma unat_ucast_up_simp:
   fixes x :: "'a::len word"
   assumes "LENGTH('a) \<le> LENGTH('b)"
   shows "unat (ucast x :: 'b::len word) = unat x"
   unfolding ucast_eq unat_eq_nat_uint
   apply (subst int_word_uint)
   apply (subst mod_pos_pos_trivial; simp?)
   apply (rule lt2p_lem)
   apply (simp add: assms)
   done
 
 lemma unat_ucast_less_no_overflow:
   "\<lbrakk>n < 2 ^ LENGTH('a); unat f < n\<rbrakk> \<Longrightarrow> (f::('a::len) word) < of_nat n"
   by (erule (1)  order_le_less_trans[OF _ of_nat_mono_maybe,rotated]) simp
 
 lemma unat_ucast_less_no_overflow_simp:
   "n < 2 ^ LENGTH('a) \<Longrightarrow> (unat f < n) = ((f::('a::len) word) < of_nat n)"
   using unat_less_helper unat_ucast_less_no_overflow by blast
 
 lemma unat_ucast_no_overflow_le:
   assumes no_overflow: "unat b < (2 :: nat) ^ LENGTH('a)"
   and upward_cast: "LENGTH('a) < LENGTH('b)"
   shows "(ucast (f::'a::len word) < (b :: 'b :: len word)) = (unat f < unat b)"
 proof -
   have LR: "ucast f < b \<Longrightarrow> unat f < unat b"
     apply (rule unat_less_helper)
     apply (simp add:ucast_nat_def)
     apply (rule_tac 'b1 = 'b in  ucast_less_ucast[OF order.strict_implies_order, THEN iffD1])
      apply (rule upward_cast)
     apply (simp add: ucast_ucast_mask less_mask_eq word_less_nat_alt
                      unat_power_lower[OF upward_cast] no_overflow)
     done
   have RL: "unat f < unat b \<Longrightarrow> ucast f < b"
   proof-
     assume ineq: "unat f < unat b"
     have "ucast (f::'a::len word) < ((ucast (ucast b ::'a::len word)) :: 'b :: len word)"
       apply (simp add: ucast_less_ucast[OF order.strict_implies_order] upward_cast)
       apply (simp only: flip: ucast_nat_def)
       apply (rule unat_ucast_less_no_overflow[OF no_overflow ineq])
       done
     then show ?thesis
       apply (rule order_less_le_trans)
       apply (simp add:ucast_ucast_mask word_and_le2)
       done
   qed
   then show ?thesis by (simp add:RL LR iffI)
 qed
 
 lemmas ucast_up_mono = ucast_less_ucast[THEN iffD2]
 
 (* casting a long word to a shorter word and casting back to the long word
    is equal to the original long word -- if the word is small enough.
   'l is the longer word.
   's is the shorter word.
 *)
 lemma bl_cast_long_short_long_ingoreLeadingZero_generic:
   "\<lbrakk> length (dropWhile Not (to_bl w)) \<le> LENGTH('s); LENGTH('s) \<le> LENGTH('l) \<rbrakk> \<Longrightarrow>
    (of_bl :: _ \<Rightarrow> 'l::len word) (to_bl ((of_bl::_ \<Rightarrow> 's::len word) (to_bl w))) = w"
   by (rule word_uint_eqI) (simp add: uint_of_bl_is_bl_to_bin uint_of_bl_is_bl_to_bin_drop)
 
 (*
  Casting between longer and shorter word.
   'l is the longer word.
   's is the shorter word.
  For example: 'l::len word is 128 word (full ipv6 address)
               's::len word is 16 word (address piece of ipv6 address in colon-text-representation)
 *)
 corollary ucast_short_ucast_long_ingoreLeadingZero:
   "\<lbrakk> length (dropWhile Not (to_bl w)) \<le> LENGTH('s); LENGTH('s) \<le> LENGTH('l) \<rbrakk> \<Longrightarrow>
    (ucast:: 's::len word \<Rightarrow> 'l::len word) ((ucast:: 'l::len word \<Rightarrow> 's::len word) w) = w"
   apply (subst ucast_bl)+
   apply (rule bl_cast_long_short_long_ingoreLeadingZero_generic; simp)
   done
 
 lemma length_drop_mask:
   fixes w::"'a::len word"
   shows "length (dropWhile Not (to_bl (w AND mask n))) \<le> n"
 proof -
   have "length (takeWhile Not (replicate n False @ ls)) = n + length (takeWhile Not ls)"
     for ls n by(subst takeWhile_append2) simp+
   then show ?thesis
     unfolding bl_and_mask by (simp add: dropWhile_eq_drop)
 qed
 
 lemma minus_one_word:
   "(-1 :: 'a :: len word) = 2 ^ LENGTH('a) - 1"
   by simp
 
 lemma mask_exceed:
   "n \<ge> LENGTH('a) \<Longrightarrow> (x::'a::len word) && ~~ (mask n) = 0"
   by (simp add: and_not_mask shiftr_eq_0)
 
 lemma two_power_strict_part_mono:
   "strict_part_mono {..LENGTH('a) - 1} (\<lambda>x. (2 :: 'a :: len word) ^ x)"
 proof -
   { fix n
     have "n < LENGTH('a) \<Longrightarrow> strict_part_mono {..n} (\<lambda>x. (2 :: 'a :: len word) ^ x)"
     proof (induct n)
       case 0 then show ?case by simp
     next
       case (Suc n)
       from Suc.prems
       have "2 ^ n < (2 :: 'a :: len word) ^ Suc n"
         using power_strict_increasing unat_power_lower word_less_nat_alt by fastforce
       with Suc
       show ?case by (subst strict_part_mono_by_steps) simp
     qed
   }
   then show ?thesis by simp
 qed
 
 lemma word_shift_by_2:
   "x * 4 = (x::'a::len word) << 2"
   by (simp add: shiftl_t2n)
 
 lemma le_2p_upper_bits:
   "\<lbrakk> (p::'a::len word) \<le> 2^n - 1; n < LENGTH('a) \<rbrakk> \<Longrightarrow>
   \<forall>n'\<ge>n. n' < LENGTH('a) \<longrightarrow> \<not> p !! n'"
   by (subst upper_bits_unset_is_l2p; simp)
 
 lemma le2p_bits_unset:
   "p \<le> 2 ^ n - 1 \<Longrightarrow> \<forall>n'\<ge>n. n' < LENGTH('a) \<longrightarrow> \<not> (p::'a::len word) !! n'"
   using upper_bits_unset_is_l2p [where p=p]
   by (cases "n < LENGTH('a)") auto
 
 lemma ucast_less_shiftl_helper:
   "\<lbrakk> LENGTH('b) + 2 < LENGTH('a); 2 ^ (LENGTH('b) + 2) \<le> n\<rbrakk>
     \<Longrightarrow> (ucast (x :: 'b::len word) << 2) < (n :: 'a::len word)"
   apply (erule order_less_le_trans[rotated])
   using ucast_less[where x=x and 'a='a]
   apply (simp only: shiftl_t2n field_simps)
   apply (rule word_less_power_trans2; simp)
   done
 
 lemma word_power_nonzero:
   "\<lbrakk> (x :: 'a::len word) < 2 ^ (LENGTH('a) - n); n < LENGTH('a); x \<noteq> 0 \<rbrakk>
   \<Longrightarrow> x * 2 ^ n \<noteq> 0"
   by (metis and_mask_eq_iff_shiftr_0 less_mask_eq p2_gt_0 semiring_normalization_rules(7)
             shiftl_shiftr_id shiftl_t2n)
 
 lemma less_1_helper:
   "n \<le> m \<Longrightarrow> (n - 1 :: int) < m"
   by arith
 
 lemma div_power_helper:
   "\<lbrakk> x \<le> y; y < LENGTH('a) \<rbrakk> \<Longrightarrow> (2 ^ y - 1) div (2 ^ x :: 'a::len word) = 2 ^ (y - x) - 1"
   apply (rule word_uint.Rep_eqD)
   apply (simp only: uint_word_ariths uint_div uint_power_lower)
   apply (subst mod_pos_pos_trivial, fastforce, fastforce)+
   apply (subst mod_pos_pos_trivial)
     apply (simp add: le_diff_eq uint_2p_alt)
    apply (rule less_1_helper)
    apply (rule power_increasing; simp)
   apply (subst mod_pos_pos_trivial)
     apply (simp add: uint_2p_alt)
    apply (rule less_1_helper)
    apply (rule power_increasing; simp)
   apply (subst int_div_sub_1; simp add: uint_2p_alt)
   apply (subst power_0[symmetric])
   apply (simp add: uint_2p_alt le_imp_power_dvd power_sub_int)
   done
 
 
 lemma word_add_power_off:
   fixes a :: "'a :: len word"
   assumes ak: "a < k"
   and kw: "k < 2 ^ (LENGTH('a) - m)"
   and mw: "m < LENGTH('a)"
   and off: "off < 2 ^ m"
   shows "(a * 2 ^ m) + off < k * 2 ^ m"
 proof (cases "m = 0")
   case True
   then show ?thesis using off ak by simp
 next
   case False
 
   from ak have ak1: "a + 1 \<le> k" by (rule inc_le)
   then have "(a + 1) * 2 ^ m \<noteq> 0"
     apply -
     apply (rule word_power_nonzero)
     apply (erule order_le_less_trans  [OF _ kw])
     apply (rule mw)
     apply (rule less_is_non_zero_p1 [OF ak])
     done
   then have "(a * 2 ^ m) + off < ((a + 1) * 2 ^ m)" using kw mw
     apply -
     apply (simp add: distrib_right)
     apply (rule word_plus_strict_mono_right [OF off])
     apply (rule is_aligned_no_overflow'')
     apply (rule is_aligned_mult_triv2)
     apply assumption
     done
   also have "\<dots> \<le> k * 2 ^ m" using ak1 mw kw False
     apply -
     apply (erule word_mult_le_mono1)
     apply (simp add: p2_gt_0)
     apply (simp add: word_less_nat_alt)
     apply (rule nat_less_power_trans2[simplified])
     apply (simp add: word_less_nat_alt)
     apply simp
     done
   finally show ?thesis .
 qed
 
 lemma offset_not_aligned:
   "\<lbrakk> is_aligned (p::'a::len word) n; i > 0; i < 2 ^ n; n < LENGTH('a)\<rbrakk> \<Longrightarrow>
    \<not> is_aligned (p + of_nat i) n"
   apply (erule is_aligned_add_not_aligned)
   unfolding is_aligned_def
   by (metis le_unat_uoi nat_dvd_not_less order_less_imp_le unat_power_lower)
 
 lemma length_upto_enum_one:
   fixes x :: "'a :: len word"
   assumes lt1: "x < y" and lt2: "z < y" and lt3: "x \<le> z"
   shows "[x , y .e. z] = [x]"
   unfolding upto_enum_step_def
 proof (subst upto_enum_red, subst if_not_P [OF leD [OF lt3]], clarsimp, rule conjI)
   show "unat ((z - x) div (y - x)) = 0"
   proof (subst unat_div, rule div_less)
     have syx: "unat (y - x) = unat y - unat x"
       by (rule unat_sub [OF order_less_imp_le]) fact
     moreover have "unat (z - x) = unat z - unat x"
       by (rule unat_sub) fact
 
     ultimately show "unat (z - x) < unat (y - x)"
       using lt2 lt3 unat_mono word_less_minus_mono_left by blast
   qed
 
   then show "(z - x) div (y - x) * (y - x) = 0"
     by (metis mult_zero_left unat_0 word_unat.Rep_eqD)
 qed
 
 lemma max_word_mask:
   "(max_word :: 'a::len word) = mask LENGTH('a)"
   unfolding mask_eq_decr_exp by simp
 
 lemmas mask_len_max = max_word_mask[symmetric]
 
 lemma is_aligned_alignUp[simp]:
   "is_aligned (alignUp p n) n"
   by (simp add: alignUp_def complement_def is_aligned_mask mask_eq_decr_exp word_bw_assocs)
 
 lemma alignUp_le[simp]:
   "alignUp p n \<le> p + 2 ^ n - 1"
   unfolding alignUp_def by (rule word_and_le2)
 
 lemma complement_mask:
   "complement (2 ^ n - 1) = ~~ (mask n)"
   unfolding complement_def mask_eq_decr_exp by simp
 
 lemma alignUp_idem:
   fixes a :: "'a::len word"
   assumes "is_aligned a n" "n < LENGTH('a)"
   shows "alignUp a n = a"
   using assms unfolding alignUp_def
   by (metis complement_mask is_aligned_add_helper p_assoc_help power_2_ge_iff)
 
 lemma alignUp_not_aligned_eq:
   fixes a :: "'a :: len word"
   assumes al: "\<not> is_aligned a n"
   and     sz: "n < LENGTH('a)"
   shows   "alignUp a n = (a div 2 ^ n + 1) * 2 ^ n"
 proof -
   have anz: "a mod 2 ^ n \<noteq> 0"
     by (rule not_aligned_mod_nz) fact+
 
   then have um: "unat (a mod 2 ^ n - 1) div 2 ^ n = 0" using sz
     by (meson Euclidean_Division.div_eq_0_iff le_m1_iff_lt measure_unat order_less_trans
               unat_less_power word_less_sub_le word_mod_less_divisor)
 
   have "a + 2 ^ n - 1 = (a div 2 ^ n) * 2 ^ n + (a mod 2 ^ n) + 2 ^ n - 1"
     by (simp add: word_mod_div_equality)
   also have "\<dots> = (a mod 2 ^ n - 1) + (a div 2 ^ n + 1) * 2 ^ n"
     by (simp add: field_simps)
   finally show "alignUp a n = (a div 2 ^ n + 1) * 2 ^ n" using sz
     unfolding alignUp_def
     apply (subst complement_mask)
     apply (erule ssubst)
     apply (subst neg_mask_is_div)
     apply (simp add: word_arith_nat_div)
     apply (subst unat_word_ariths(1) unat_word_ariths(2))+
     apply (subst uno_simps)
     apply (subst unat_1)
     apply (subst mod_add_right_eq)
     apply simp
     apply (subst power_mod_div)
     apply (subst div_mult_self1)
      apply simp
     apply (subst um)
     apply simp
     apply (subst mod_mod_power)
     apply simp
     apply (subst word_unat_power, subst Abs_fnat_hom_mult)
     apply (subst mult_mod_left)
     apply (subst power_add [symmetric])
     apply simp
     apply (subst Abs_fnat_hom_1)
     apply (subst Abs_fnat_hom_add)
     apply (subst word_unat_power, subst Abs_fnat_hom_mult)
     apply (subst word_unat.Rep_inverse[symmetric], subst Abs_fnat_hom_mult)
     apply simp
     done
 qed
 
 lemma alignUp_ge:
   fixes a :: "'a :: len word"
   assumes sz: "n < LENGTH('a)"
   and nowrap: "alignUp a n \<noteq> 0"
   shows "a \<le> alignUp a n"
 proof (cases "is_aligned a n")
   case True
   then show ?thesis using sz
     by (subst alignUp_idem, simp_all)
 next
   case False
 
   have lt0: "unat a div 2 ^ n < 2 ^ (LENGTH('a) - n)" using sz
     by (metis shiftr_div_2n' word_shiftr_lt)
 
   have"2 ^ n * (unat a div 2 ^ n + 1) \<le> 2 ^ LENGTH('a)" using sz
     by (metis One_nat_def Suc_leI add.right_neutral add_Suc_right lt0 nat_le_power_trans nat_less_le)
   moreover have "2 ^ n * (unat a div 2 ^ n + 1) \<noteq> 2 ^ LENGTH('a)" using nowrap sz
     apply -
     apply (erule contrapos_nn)
     apply (subst alignUp_not_aligned_eq [OF False sz])
     apply (subst unat_arith_simps)
     apply (subst unat_word_ariths)
     apply (subst unat_word_ariths)
     apply simp
     apply (subst mult_mod_left)
     apply (simp add: unat_div field_simps power_add[symmetric] mod_mod_power min.absorb2)
     done
   ultimately have lt: "2 ^ n * (unat a div 2 ^ n + 1) < 2 ^ LENGTH('a)" by simp
 
   have "a = a div 2 ^ n * 2 ^ n + a mod 2 ^ n" by (rule word_mod_div_equality [symmetric])
   also have "\<dots> < (a div 2 ^ n + 1) * 2 ^ n" using sz lt
     apply (simp add: field_simps)
     apply (rule word_add_less_mono1)
     apply (rule word_mod_less_divisor)
     apply (simp add: word_less_nat_alt)
     apply (subst unat_word_ariths)
     apply (simp add: unat_div)
     done
   also have "\<dots> =  alignUp a n"
     by (rule alignUp_not_aligned_eq [symmetric]) fact+
   finally show ?thesis by (rule order_less_imp_le)
 qed
 
 lemma alignUp_le_greater_al:
   fixes x :: "'a :: len word"
   assumes le: "a \<le> x"
   and     sz: "n < LENGTH('a)"
   and     al: "is_aligned x n"
   shows   "alignUp a n \<le> x"
 proof (cases "is_aligned a n")
   case True
   then show ?thesis using sz le by (simp add: alignUp_idem)
 next
   case False
 
   then have anz: "a mod 2 ^ n \<noteq> 0"
     by (rule not_aligned_mod_nz)
 
   from al obtain k where xk: "x = 2 ^ n * of_nat k" and kv: "k < 2 ^ (LENGTH('a) - n)"
     by (auto elim!: is_alignedE)
 
   then have kn: "unat (of_nat k :: 'a word) * unat ((2::'a word) ^ n) < 2 ^ LENGTH('a)"
     using sz
     apply (subst unat_of_nat_eq)
      apply (erule order_less_le_trans)
      apply simp
     apply (subst mult.commute)
     apply simp
     apply (rule nat_less_power_trans)
      apply simp
     apply simp
     done
 
   have au: "alignUp a n = (a div 2 ^ n + 1) * 2 ^ n"
     by (rule alignUp_not_aligned_eq) fact+
   also have "\<dots> \<le> of_nat k * 2 ^ n"
   proof (rule word_mult_le_mono1 [OF inc_le _ kn])
     show "a div 2 ^ n < of_nat k" using kv xk le sz anz
       by (simp add: alignUp_div_helper)
 
     show "(0:: 'a word) < 2 ^ n" using sz by (simp add: p2_gt_0 sz)
   qed
 
   finally show ?thesis using xk by (simp add: field_simps)
 qed
 
 lemma alignUp_is_aligned_nz:
   fixes a :: "'a :: len word"
   assumes al: "is_aligned x n"
   and     sz: "n < LENGTH('a)"
   and     ax: "a \<le> x"
   and     az: "a \<noteq> 0"
   shows   "alignUp (a::'a :: len word) n \<noteq> 0"
 proof (cases "is_aligned a n")
   case True
   then have "alignUp a n = a" using sz by (simp add: alignUp_idem)
   then show ?thesis using az by simp
 next
   case False
   then have anz: "a mod 2 ^ n \<noteq> 0"
     by (rule not_aligned_mod_nz)
 
   {
     assume asm: "alignUp a n = 0"
 
     have lt0: "unat a div 2 ^ n < 2 ^ (LENGTH('a) - n)" using sz
       by (metis shiftr_div_2n' word_shiftr_lt)
 
     have leq: "2 ^ n * (unat a div 2 ^ n + 1) \<le> 2 ^ LENGTH('a)" using sz
       by (metis One_nat_def Suc_leI add.right_neutral add_Suc_right lt0 nat_le_power_trans
                 order_less_imp_le)
 
     from al obtain k where  kv: "k < 2 ^ (LENGTH('a) - n)" and xk: "x = 2 ^ n * of_nat k"
       by (auto elim!: is_alignedE)
 
     then have "a div 2 ^ n < of_nat k" using ax sz anz
       by (rule alignUp_div_helper)
 
     then have r: "unat a div 2 ^ n < k" using sz
       by (metis unat_div unat_less_helper unat_power_lower)
 
     have "alignUp a n = (a div 2 ^ n + 1) * 2 ^ n"
       by (rule alignUp_not_aligned_eq) fact+
 
     then have "\<dots> = 0" using asm by simp
     then have "2 ^ LENGTH('a) dvd 2 ^ n * (unat a div 2 ^ n + 1)"
       using sz by (simp add: unat_arith_simps ac_simps)
                   (simp add: unat_word_ariths mod_simps mod_eq_0_iff_dvd)
     with leq have "2 ^ n * (unat a div 2 ^ n + 1) = 2 ^ LENGTH('a)"
       by (force elim!: le_SucE)
     then have "unat a div 2 ^ n = 2 ^ LENGTH('a) div 2 ^ n - 1"
       by (metis (no_types, hide_lams) Groups.add_ac(2) add.right_neutral
                 add_diff_cancel_left' div_le_dividend div_mult_self4 gr_implies_not0
                 le_neq_implies_less power_eq_0_iff zero_neq_numeral)
     then have "unat a div 2 ^ n = 2 ^ (LENGTH('a) - n) - 1"
       using sz by (simp add: power_sub)
     then have "2 ^ (LENGTH('a) - n) - 1 < k" using r
       by simp
     then have False using kv by simp
   } then show ?thesis by clarsimp
 qed
 
 lemma alignUp_ar_helper:
   fixes a :: "'a :: len word"
   assumes al: "is_aligned x n"
   and     sz: "n < LENGTH('a)"
   and    sub: "{x..x + 2 ^ n - 1} \<subseteq> {a..b}"
   and    anz: "a \<noteq> 0"
   shows "a \<le> alignUp a n \<and> alignUp a n + 2 ^ n - 1 \<le> b"
 proof
   from al have xl: "x \<le> x + 2 ^ n - 1" by (simp add: is_aligned_no_overflow)
 
   from xl sub have ax: "a \<le> x"
     by (clarsimp elim!: range_subset_lower [where x = x])
 
   show "a \<le> alignUp a n"
   proof (rule alignUp_ge)
     show "alignUp a n \<noteq> 0" using al sz ax anz
       by (rule alignUp_is_aligned_nz)
   qed fact+
 
   show "alignUp a n + 2 ^ n - 1 \<le> b"
   proof (rule order_trans)
     from xl show tp: "x + 2 ^ n - 1 \<le> b" using sub
       by (clarsimp elim!: range_subset_upper [where x = x])
 
     from ax have "alignUp a n \<le> x"
       by (rule alignUp_le_greater_al) fact+
     then have "alignUp a n + (2 ^ n - 1) \<le> x + (2 ^ n - 1)"
       using xl al is_aligned_no_overflow' olen_add_eqv word_plus_mcs_3 by blast
     then show "alignUp a n + 2 ^ n - 1 \<le> x + 2 ^ n - 1"
       by (simp add: field_simps)
   qed
 qed
 
 lemma alignUp_def2:
   "alignUp a sz = a + 2 ^ sz - 1 && ~~ (mask sz)"
   unfolding alignUp_def[unfolded complement_def]
   by (simp add:mask_eq_decr_exp[symmetric,unfolded shiftl_t2n,simplified])
 
 lemma mask_out_first_mask_some:
   "\<lbrakk> x && ~~ (mask n) = y; n \<le> m \<rbrakk> \<Longrightarrow> x && ~~ (mask m) = y && ~~ (mask m)"
   by word_eqI_solve
 
 lemma gap_between_aligned:
   "\<lbrakk>a < (b :: 'a ::len word); is_aligned a n; is_aligned b n; n < LENGTH('a) \<rbrakk>
   \<Longrightarrow> a + (2^n - 1) < b"
   by (simp add: aligned_add_offset_less)
 
 lemma mask_out_add_aligned:
   assumes al: "is_aligned p n"
   shows "p + (q && ~~ (mask n)) = (p + q) && ~~ (mask n)"
   using mask_add_aligned [OF al]
   by (simp add: mask_out_sub_mask)
 
 lemma alignUp_def3:
   "alignUp a sz = 2^ sz + (a - 1 && ~~ (mask sz))"
   by (simp add: alignUp_def2 is_aligned_triv field_simps mask_out_add_aligned)
 
 lemma  alignUp_plus:
   "is_aligned w us \<Longrightarrow> alignUp (w + a) us  = w + alignUp a us"
   by (clarsimp simp: alignUp_def2 mask_out_add_aligned field_simps)
 
 lemma mask_lower_twice:
   "n \<le> m \<Longrightarrow> (x && ~~ (mask n)) && ~~ (mask m) = x && ~~ (mask m)"
   by word_eqI_solve
 
 lemma mask_lower_twice2:
   "(a && ~~ (mask n)) && ~~ (mask m) = a && ~~ (mask (max n m))"
   by word_eqI_solve
 
 lemma ucast_and_neg_mask:
   "ucast (x && ~~ (mask n)) = ucast x && ~~ (mask n)"
   by word_eqI_solve
 
 lemma ucast_and_mask:
   "ucast (x && mask n) = ucast x && mask n"
   by word_eqI_solve
 
 lemma ucast_mask_drop:
   "LENGTH('a :: len) \<le> n \<Longrightarrow> (ucast (x && mask n) :: 'a word) = ucast x"
   by word_eqI
 
 lemma alignUp_distance:
   "alignUp (q :: 'a :: len word) sz - q \<le> mask sz"
   by (metis (no_types) add.commute add_diff_cancel_left alignUp_def2 diff_add_cancel
                        mask_2pm1 subtract_mask(2) word_and_le1 word_sub_le_iff)
 
 lemma is_aligned_diff_neg_mask:
   "is_aligned p sz \<Longrightarrow> (p - q && ~~ (mask sz)) = (p - ((alignUp q sz) && ~~ (mask sz)))"
   apply (clarsimp simp only:word_and_le2 diff_conv_add_uminus)
   apply (subst mask_out_add_aligned[symmetric]; simp)
   apply (rule sum_to_zero)
   apply (subst add.commute)
   by (simp add: alignUp_distance and_mask_0_iff_le_mask is_aligned_neg_mask_eq mask_out_add_aligned)
 
 lemma map_bits_rev_to_bl:
   "map ((!!) x) [0..<size x] = rev (to_bl x)"
   by (auto simp: list_eq_iff_nth_eq test_bit_bl word_size)
 
 (* negating a mask which has been shifted to the very left *)
 lemma NOT_mask_shifted_lenword:
   "~~ (mask len << (LENGTH('a) - len) ::'a::len word) = mask (LENGTH('a) - len)"
   by (rule bit_word_eqI)
     (auto simp add: shiftl_word_eq word_size bit_not_iff bit_push_bit_iff bit_mask_iff)
 
 (* Comparisons between different word sizes. *)
 
 lemma eq_ucast_ucast_eq:
   "LENGTH('b) \<le> LENGTH('a) \<Longrightarrow> x = ucast y \<Longrightarrow> ucast x = y"
   for x :: "'a::len word" and y :: "'b::len word"
   by (simp add: is_down ucast_ucast_a)
 
 lemma le_ucast_ucast_le:
   "x \<le> ucast y \<Longrightarrow> ucast x \<le> y"
   for x :: "'a::len word" and y :: "'b::len word"
   by (smt le_unat_uoi linorder_not_less order_less_imp_le ucast_nat_def unat_arith_simps(1))
 
 lemma less_ucast_ucast_less:
   "LENGTH('b) \<le> LENGTH('a) \<Longrightarrow> x < ucast y \<Longrightarrow> ucast x < y"
   for x :: "'a::len word" and y :: "'b::len word"
   by (metis ucast_nat_def unat_mono unat_ucast_up_simp word_of_nat_less)
 
 lemma ucast_le_ucast:
   "LENGTH('a) \<le> LENGTH('b) \<Longrightarrow> (ucast x \<le> (ucast y::'b::len word)) = (x \<le> y)"
   for x :: "'a::len word"
   by (simp add: unat_arith_simps(1) unat_ucast_up_simp)
 
 lemmas ucast_up_mono_le = ucast_le_ucast[THEN iffD2]
 
 lemma ucast_le_ucast_eq:
   fixes x y :: "'a::len word"
   assumes x: "x < 2 ^ n"
   assumes y: "y < 2 ^ n"
   assumes n: "n = LENGTH('b::len)"
   shows "(UCAST('a \<rightarrow> 'b) x \<le> UCAST('a \<rightarrow> 'b) y) = (x \<le> y)"
   apply (rule iffI)
    apply (cases "LENGTH('b) < LENGTH('a)")
     apply (subst less_mask_eq[OF x, symmetric])
     apply (subst less_mask_eq[OF y, symmetric])
     apply (unfold n)
     apply (subst ucast_ucast_mask[symmetric])+
     apply (simp add: ucast_le_ucast)+
   apply (erule ucast_mono_le[OF _ y[unfolded n]])
   done
 
 lemma word_le_not_less:
   "((b::'a::len word) \<le> a) = (\<not>(a < b))"
   by fastforce
 
 lemma ucast_or_distrib:
   fixes x :: "'a::len word"
   fixes y :: "'a::len word"
   shows "(ucast (x || y) :: ('b::len) word) = ucast x || ucast y"
   by transfer simp
 
 lemma shiftr_less:
   "(w::'a::len word) < k \<Longrightarrow> w >> n < k"
   by (metis div_le_dividend le_less_trans shiftr_div_2n' unat_arith_simps(2))
 
 lemma word_and_notzeroD:
   "w && w' \<noteq> 0 \<Longrightarrow> w \<noteq> 0 \<and> w' \<noteq> 0"
   by auto
 
 lemma word_clz_max:
   "word_clz w \<le> size (w::'a::len word)"
   unfolding word_clz_def
   by (metis length_takeWhile_le word_size_bl)
 
 lemma word_clz_nonzero_max:
   fixes w :: "'a::len word"
   assumes nz: "w \<noteq> 0"
   shows "word_clz w < size (w::'a::len word)"
 proof -
   {
     assume a: "word_clz w = size (w::'a::len word)"
     hence "length (takeWhile Not (to_bl w)) = length (to_bl w)"
       by (simp add: word_clz_def word_size)
     hence allj: "\<forall>j\<in>set(to_bl w). \<not> j"
       by (metis a length_takeWhile_less less_irrefl_nat word_clz_def)
     hence "to_bl w = replicate (length (to_bl w)) False"
       by (fastforce intro!: list_of_false)
     hence "w = 0"
       by (metis to_bl_0 word_bl.Rep_eqD word_bl_Rep')
     with nz have False by simp
   }
   thus ?thesis using word_clz_max
     by (fastforce intro: le_neq_trans)
 qed
 
 lemma unat_add_lem':
   "(unat x + unat y < 2 ^ LENGTH('a)) \<Longrightarrow>
     (unat (x + y :: 'a :: len word) = unat x + unat y)"
   by (subst unat_add_lem[symmetric], assumption)
 
 lemma from_bool_eq_if':
   "((if P then 1 else 0) = from_bool Q) = (P = Q)"
   by (simp add: case_bool_If from_bool_def split: if_split)
 
 lemma word_exists_nth:
   "(w::'a::len word) \<noteq> 0 \<Longrightarrow> \<exists>i. w !! i"
   using word_log2_nth_same by blast
 
 lemma shiftr_le_0:
   "unat (w::'a::len word) < 2 ^ n \<Longrightarrow> w >> n = (0::'a::len word)"
   by (rule word_unat.Rep_eqD) (simp add: shiftr_div_2n')
 
 lemma of_nat_shiftl:
   "(of_nat x << n) = (of_nat (x * 2 ^ n) :: ('a::len) word)"
 proof -
   have "(of_nat x::'a word) << n = of_nat (2 ^ n) * of_nat x"
     using shiftl_t2n by (metis word_unat_power)
   thus ?thesis by simp
 qed
 
 lemma shiftl_1_not_0:
   "n < LENGTH('a) \<Longrightarrow> (1::'a::len word) << n \<noteq> 0"
   by (simp add: shiftl_t2n)
 
 lemma max_word_not_0 [simp]:
   "- 1 \<noteq> (0 :: 'a::len word)"
   by simp
 
 lemma ucast_zero_is_aligned:
   "UCAST('a::len \<rightarrow> 'b::len) w = 0 \<Longrightarrow> n \<le> LENGTH('b) \<Longrightarrow> is_aligned w n"
   by (clarsimp simp: is_aligned_mask word_eq_iff word_size nth_ucast)
 
 lemma unat_ucast_eq_unat_and_mask:
   "unat (UCAST('b::len \<rightarrow> 'a::len) w) = unat (w && mask LENGTH('a))"
   proof -
     have "unat (UCAST('b \<rightarrow> 'a) w) = unat (UCAST('a \<rightarrow> 'b) (UCAST('b \<rightarrow> 'a) w))"
       by (cases "LENGTH('a) < LENGTH('b)"; simp add: is_down ucast_ucast_a unat_ucast_up_simp)
     thus ?thesis using ucast_ucast_mask by simp
   qed
 
 lemma unat_max_word_pos[simp]: "0 < unat (- 1 :: 'a::len word)"
   using unat_gt_0 [of \<open>- 1 :: 'a::len word\<close>] by simp
 
 
 (* Miscellaneous conditional injectivity rules. *)
 
 lemma mult_pow2_inj:
   assumes ws: "m + n \<le> LENGTH('a)"
   assumes le: "x \<le> mask m" "y \<le> mask m"
   assumes eq: "x * 2^n = y * (2^n::'a::len word)"
   shows "x = y"
 proof (cases n)
   case 0 thus ?thesis using eq by simp
 next
   case (Suc n')
   have m_lt: "m < LENGTH('a)" using Suc ws by simp
   have xylt: "x < 2^m" "y < 2^m" using le m_lt unfolding mask_2pm1 by auto
   have lenm: "n \<le> LENGTH('a) - m" using ws by simp
   show ?thesis
     using eq xylt
     apply (fold shiftl_t2n[where n=n, simplified mult.commute])
     apply (simp only: word_bl.Rep_inject[symmetric] bl_shiftl)
     apply (erule ssubst[OF less_is_drop_replicate])+
     apply (clarsimp elim!: drop_eq_mono[OF lenm])
     done
 qed
 
 lemma word_of_nat_inj:
   assumes bounded: "x < 2 ^ LENGTH('a)" "y < 2 ^ LENGTH('a)"
   assumes of_nats: "of_nat x = (of_nat y :: 'a::len word)"
   shows "x = y"
   by (rule contrapos_pp[OF of_nats]; cases "x < y"; cases "y < x")
      (auto dest: bounded[THEN of_nat_mono_maybe])
 
 (* Sign extension from bit n. *)
 
 lemma sign_extend_bitwise_if:
   "i < size w \<Longrightarrow> sign_extend e w !! i \<longleftrightarrow> (if i < e then w !! i else w !! e)"
   by (simp add: sign_extend_def neg_mask_test_bit word_size)
 
 lemma sign_extend_bitwise_disj:
   "i < size w \<Longrightarrow> sign_extend e w !! i \<longleftrightarrow> i \<le> e \<and> w !! i \<or> e \<le> i \<and> w !! e"
   by (auto simp: sign_extend_bitwise_if)
 
 lemma sign_extend_bitwise_cases:
   "i < size w \<Longrightarrow> sign_extend e w !! i \<longleftrightarrow> (i \<le> e \<longrightarrow> w !! i) \<and> (e \<le> i \<longrightarrow> w !! e)"
   by (auto simp: sign_extend_bitwise_if)
 
 lemmas sign_extend_bitwise_if'[word_eqI_simps] = sign_extend_bitwise_if[simplified word_size]
 lemmas sign_extend_bitwise_disj' = sign_extend_bitwise_disj[simplified word_size]
 lemmas sign_extend_bitwise_cases' = sign_extend_bitwise_cases[simplified word_size]
 
 (* Often, it is easier to reason about an operation which does not overwrite
    the bit which determines which mask operation to apply. *)
 lemma sign_extend_def':
   "sign_extend n w = (if w !! n then w || ~~ (mask (Suc n)) else w && mask (Suc n))"
   by word_eqI (auto dest: less_antisym)
 
 lemma sign_extended_sign_extend:
   "sign_extended n (sign_extend n w)"
   by (clarsimp simp: sign_extended_def word_size sign_extend_bitwise_if')
 
 lemma sign_extended_iff_sign_extend:
   "sign_extended n w \<longleftrightarrow> sign_extend n w = w"
   apply (rule iffI)
    apply (word_eqI, rename_tac i)
    apply (case_tac "n < i"; simp add: sign_extended_def word_size)
   apply (erule subst, rule sign_extended_sign_extend)
   done
 
 lemma sign_extended_weaken:
   "sign_extended n w \<Longrightarrow> n \<le> m \<Longrightarrow> sign_extended m w"
   unfolding sign_extended_def by (cases "n < m") auto
 
 lemma sign_extend_sign_extend_eq:
   "sign_extend m (sign_extend n w) = sign_extend (min m n) w"
   by word_eqI
 
 lemma sign_extended_high_bits:
   "\<lbrakk> sign_extended e p; j < size p; e \<le> i; i < j \<rbrakk> \<Longrightarrow> p !! i = p !! j"
   by (drule (1) sign_extended_weaken; simp add: sign_extended_def)
 
 lemma sign_extend_eq:
   "w && mask (Suc n) = v && mask (Suc n) \<Longrightarrow> sign_extend n w = sign_extend n v"
   by word_eqI_solve
 
 lemma sign_extended_add:
   assumes p: "is_aligned p n"
   assumes f: "f < 2 ^ n"
   assumes e: "n \<le> e"
   assumes "sign_extended e p"
   shows "sign_extended e (p + f)"
 proof (cases "e < size p")
   case True
   note and_or = is_aligned_add_or[OF p f]
   have "\<not> f !! e"
     using True e less_2p_is_upper_bits_unset[THEN iffD1, OF f]
     by (fastforce simp: word_size)
   hence i: "(p + f) !! e = p !! e"
     by (simp add: and_or)
   have fm: "f && mask e = f"
     by (fastforce intro: subst[where P="\<lambda>f. f && mask e = f", OF less_mask_eq[OF f]]
                   simp: mask_twice e)
   show ?thesis
     using assms
      apply (simp add: sign_extended_iff_sign_extend sign_extend_def i)
      apply (simp add: and_or word_bw_comms[of p f])
      apply (clarsimp simp: word_ao_dist fm word_bw_assocs split: if_splits)
     done
 next
   case False thus ?thesis
     by (simp add: sign_extended_def word_size)
 qed
 
 lemma sign_extended_neq_mask:
   "\<lbrakk>sign_extended n ptr; m \<le> n\<rbrakk> \<Longrightarrow> sign_extended n (ptr && ~~ (mask m))"
   by (fastforce simp: sign_extended_def word_size neg_mask_test_bit)
 
 (* Uints *)
 
 lemma uints_mono_iff: "uints l \<subseteq> uints m \<longleftrightarrow> l \<le> m"
   using power_increasing_iff[of "2::int" l m]
   apply (auto simp: uints_num subset_iff simp del: power_increasing_iff)
   by (meson less_irrefl not_less zle2p)
 
 lemmas uints_monoI = uints_mono_iff[THEN iffD2]
 
 lemma Bit_in_uints_Suc: "of_bool c + 2 * w \<in> uints (Suc m)" if "w \<in> uints m"
   using that
   by (auto simp: uints_num)
 
 lemma Bit_in_uintsI: "of_bool c + 2 * w \<in> uints m" if "w \<in> uints (m - 1)" "m > 0"
   using Bit_in_uints_Suc[OF that(1)] that(2)
   by auto
 
 lemma bin_cat_in_uintsI:
   \<open>bin_cat a n b \<in> uints m\<close> if \<open>a \<in> uints l\<close> \<open>m \<ge> l + n\<close>
 proof -
   from \<open>m \<ge> l + n\<close> obtain q where \<open>m = l + n + q\<close>
     using le_Suc_ex by blast
   then have \<open>(2::int) ^ m = 2 ^ n * 2 ^ (l + q)\<close>
     by (simp add: ac_simps power_add)
   moreover have \<open>a mod 2 ^ (l + q) = a\<close>
     using \<open>a \<in> uints l\<close>
     by (auto simp add: uints_def take_bit_eq_mod power_add Divides.mod_mult2_eq)
   ultimately have \<open>concat_bit n b a = take_bit m (concat_bit n b a)\<close>
     by (simp add: concat_bit_eq take_bit_eq_mod push_bit_eq_mult Divides.mod_mult2_eq)
   then show ?thesis
     by (simp add: uints_def)
 qed
 
 lemma bin_cat_cong: "bin_cat a n b = bin_cat c m d"
   if "n = m" "a = c" "bintrunc m b = bintrunc m d"
   using that(3) unfolding that(1,2) by (simp add: bin_cat_eq_push_bit_add_take_bit)
 
 lemma bin_cat_eqD1: "bin_cat a n b = bin_cat c n d \<Longrightarrow> a = c"
   by (metis drop_bit_bin_cat_eq)
 
 lemma bin_cat_eqD2: "bin_cat a n b = bin_cat c n d \<Longrightarrow> bintrunc n b = bintrunc n d"
   by (metis take_bit_bin_cat_eq)
   
 lemma bin_cat_inj: "(bin_cat a n b) = bin_cat c n d \<longleftrightarrow> a = c \<and> bintrunc n b = bintrunc n d"
   by (auto intro: bin_cat_cong bin_cat_eqD1 bin_cat_eqD2)
 
 lemma word_of_int_bin_cat_eq_iff:
   "(word_of_int (bin_cat (uint a) LENGTH('b) (uint b))::'c::len word) =
   word_of_int (bin_cat (uint c) LENGTH('b) (uint d)) \<longleftrightarrow> b = d \<and> a = c"
   if "LENGTH('a) + LENGTH('b) \<le> LENGTH('c)"
   for a::"'a::len word" and b::"'b::len word"
   by (subst word_uint.Abs_inject)
      (auto simp: bin_cat_inj intro!: that bin_cat_in_uintsI)
 
 lemma word_cat_inj: "(word_cat a b::'c::len word) = word_cat c d \<longleftrightarrow> a = c \<and> b = d"
   if "LENGTH('a) + LENGTH('b) \<le> LENGTH('c)"
   for a::"'a::len word" and b::"'b::len word"
   using word_of_int_bin_cat_eq_iff [OF that, of b a d c]
   by transfer auto
 
 lemma p2_eq_1: "2 ^ n = (1::'a::len word) \<longleftrightarrow> n = 0"
 proof -
   have "2 ^ n = (1::'a word) \<Longrightarrow> n = 0"
     by (metis One_nat_def not_less one_less_numeral_iff p2_eq_0 p2_gt_0 power_0 power_0
         power_inject_exp semiring_norm(76) unat_power_lower zero_neq_one)
   then show ?thesis by auto
 qed
 
 (* usually: x,y = (len_of TYPE ('a)) *)
 lemma bitmagic_zeroLast_leq_or1Last:
   "(a::('a::len) word) AND (mask len << x - len) \<le> a OR mask (y - len)"
   by (meson le_word_or2 order_trans word_and_le2)
 
 
 lemma zero_base_lsb_imp_set_eq_as_bit_operation:
   fixes base ::"'a::len word"
   assumes valid_prefix: "mask (LENGTH('a) - len) AND base = 0"
   shows "(base = NOT (mask (LENGTH('a) - len)) AND a) \<longleftrightarrow>
          (a \<in> {base .. base OR mask (LENGTH('a) - len)})"
 proof
   have helper3: "x OR y = x OR y AND NOT x" for x y ::"'a::len word" by (simp add: word_oa_dist2)
   from assms show "base = NOT (mask (LENGTH('a) - len)) AND a \<Longrightarrow>
                     a \<in> {base..base OR mask (LENGTH('a) - len)}"
     apply(simp add: word_and_le1)
     apply(metis helper3 le_word_or2 word_bw_comms(1) word_bw_comms(2))
   done
 next
   assume "a \<in> {base..base OR mask (LENGTH('a) - len)}"
   hence a: "base \<le> a \<and> a \<le> base OR mask (LENGTH('a) - len)" by simp
   show "base = NOT (mask (LENGTH('a) - len)) AND a"
   proof -
     have f2: "\<forall>x\<^sub>0. base AND NOT (mask x\<^sub>0) \<le> a AND NOT (mask x\<^sub>0)"
       using a neg_mask_mono_le by blast
     have f3: "\<forall>x\<^sub>0. a AND NOT (mask x\<^sub>0) \<le> (base OR mask (LENGTH('a) - len)) AND NOT (mask x\<^sub>0)"
       using a neg_mask_mono_le by blast
     have f4: "base = base AND NOT (mask (LENGTH('a) - len))"
       using valid_prefix by (metis mask_eq_0_eq_x word_bw_comms(1))
     hence f5: "\<forall>x\<^sub>6. (base OR x\<^sub>6) AND NOT (mask (LENGTH('a) - len)) =
                       base OR x\<^sub>6 AND NOT (mask (LENGTH('a) - len))"
       using word_ao_dist by (metis)
     have f6: "\<forall>x\<^sub>2 x\<^sub>3. a AND NOT (mask x\<^sub>2) \<le> x\<^sub>3 \<or>
                       \<not> (base OR mask (LENGTH('a) - len)) AND NOT (mask x\<^sub>2) \<le> x\<^sub>3"
       using f3 dual_order.trans by auto
     have "base = (base OR mask (LENGTH('a) - len)) AND NOT (mask (LENGTH('a) - len))"
       using f5 by auto
     hence "base = a AND NOT (mask (LENGTH('a) - len))"
       using f2 f4 f6 by (metis eq_iff)
     thus "base = NOT (mask (LENGTH('a) - len)) AND a"
       by (metis word_bw_comms(1))
   qed
 qed
 
 lemma unat_minus_one_word:
   "unat (-1 :: 'a :: len word) = 2 ^ LENGTH('a) - 1"
   by (subst minus_one_word)
      (subst unat_sub_if', clarsimp)
 
 lemma of_nat_eq_signed_scast:
   "(of_nat x = (y :: ('a::len) signed word))
    = (of_nat x = (scast y :: 'a word))"
   by (metis scast_of_nat scast_scast_id(2))
 
 lemma word_ctz_le:
   "word_ctz (w :: ('a::len word)) \<le> LENGTH('a)"
   apply (clarsimp simp: word_ctz_def)
   apply (rule nat_le_Suc_less_imp[where y="LENGTH('a) + 1" , simplified])
   apply (rule order_le_less_trans[OF List.length_takeWhile_le])
   apply simp
   done
 
 lemma word_ctz_less:
   "w \<noteq> 0 \<Longrightarrow> word_ctz (w :: ('a::len word)) < LENGTH('a)"
   apply (clarsimp simp: word_ctz_def eq_zero_set_bl)
   apply (rule order_less_le_trans[OF length_takeWhile_less])
    apply fastforce+
   done
 
 lemma word_ctz_not_minus_1:
   "1 < LENGTH('a) \<Longrightarrow> of_nat (word_ctz (w :: 'a :: len word)) \<noteq> (- 1 :: 'a::len word)"
   by (metis (mono_tags) One_nat_def add.right_neutral add_Suc_right le_diff_conv le_less_trans
                         n_less_equal_power_2 not_le suc_le_pow_2 unat_minus_one_word unat_of_nat_len
                         word_ctz_le)
 
 lemma word_aligned_add_no_wrap_bounded:
   "\<lbrakk> w + 2^n \<le> x; w + 2^n \<noteq> 0; is_aligned w n \<rbrakk> \<Longrightarrow> (w::'a::len word) < x"
   by (blast dest: is_aligned_no_overflow le_less_trans word_leq_le_minus_one)
 
 lemma mask_Suc:
   "mask (Suc n) = (2 :: 'a::len word) ^ n + mask n"
   by (simp add: mask_eq_decr_exp)
 
 lemma is_aligned_no_overflow_mask:
   "is_aligned x n \<Longrightarrow> x \<le> x + mask n"
   by (simp add: mask_eq_decr_exp) (erule is_aligned_no_overflow')
 
 lemma is_aligned_mask_offset_unat:
   fixes off :: "('a::len) word"
   and     x :: "'a word"
   assumes al: "is_aligned x sz"
   and   offv: "off \<le> mask sz"
   shows  "unat x + unat off < 2 ^ LENGTH('a)"
 proof cases
   assume szv: "sz < LENGTH('a)"
   from al obtain k where xv: "x = 2 ^ sz * (of_nat k)"
     and kl: "k < 2 ^ (LENGTH('a) - sz)"
     by (auto elim: is_alignedE)
 
   from offv szv have offv': "unat off < 2 ^ sz"
     by (simp add: mask_2pm1 unat_less_power)
 
   show ?thesis using szv
     using al is_aligned_no_wrap''' offv' by blast
 next
   assume "\<not> sz < LENGTH('a)"
   with al have "x = 0" by - word_eqI
   thus ?thesis by simp
 qed
 
 lemma of_bl_max:
   "(of_bl xs :: 'a::len word) \<le> mask (length xs)"
   apply (induct xs)
    apply simp
   apply (simp add: of_bl_Cons mask_Suc)
   apply (rule conjI; clarsimp)
    apply (erule word_plus_mono_right)
    apply (rule is_aligned_no_overflow_mask)
    apply (rule is_aligned_triv)
   apply (simp add: word_le_nat_alt)
   apply (subst unat_add_lem')
    apply (rule is_aligned_mask_offset_unat)
     apply (rule is_aligned_triv)
    apply (simp add: mask_eq_decr_exp)
   apply simp
   done
 
 lemma mask_over_length:
   "LENGTH('a) \<le> n \<Longrightarrow> mask n = (-1::'a::len word)"
   by (simp add: mask_eq_decr_exp)
 
 lemma is_aligned_over_length:
   "\<lbrakk> is_aligned p n; LENGTH('a) \<le> n \<rbrakk> \<Longrightarrow> (p::'a::len word) = 0"
   by (simp add: is_aligned_mask mask_over_length)
 
 lemma Suc_2p_unat_mask:
   "n < LENGTH('a) \<Longrightarrow> Suc (2 ^ n * k + unat (mask n :: 'a::len word)) = 2 ^ n * (k+1)"
   by (simp add: unat_mask)
 
 lemma is_aligned_add_step_le:
   "\<lbrakk> is_aligned (a::'a::len word) n; is_aligned b n; a < b; b \<le> a + mask n \<rbrakk> \<Longrightarrow> False"
   apply (simp flip: not_le)
   apply (erule notE)
   apply (cases "LENGTH('a) \<le> n")
    apply (drule (1) is_aligned_over_length)+
    apply (drule mask_over_length)
    apply clarsimp
   apply (clarsimp simp: word_le_nat_alt not_less)
   apply (subst (asm) unat_plus_simple[THEN iffD1], erule is_aligned_no_overflow_mask)
   apply (clarsimp simp: is_aligned_def dvd_def word_le_nat_alt)
   apply (drule le_imp_less_Suc)
   apply (simp add: Suc_2p_unat_mask)
   by (metis Groups.mult_ac(2) Suc_leI linorder_not_less mult_le_mono order_refl times_nat.simps(2))
 
 lemma power_2_mult_step_le:
   "\<lbrakk>n' \<le> n; 2 ^ n' * k' < 2 ^ n * k\<rbrakk> \<Longrightarrow> 2 ^ n' * (k' + 1) \<le> 2 ^ n * (k::nat)"
   apply (cases "n'=n", simp)
    apply (metis Suc_leI le_refl mult_Suc_right mult_le_mono semiring_normalization_rules(7))
   apply (drule (1) le_neq_trans)
   apply clarsimp
   apply (subgoal_tac "\<exists>m. n = n' + m")
    prefer 2
    apply (simp add: le_Suc_ex)
   apply (clarsimp simp: power_add)
   by (metis Suc_leI mult.assoc mult_Suc_right nat_mult_le_cancel_disj)
 
 lemma aligned_mask_step:
   "\<lbrakk> n' \<le> n; p' \<le> p + mask n; is_aligned p n; is_aligned p' n' \<rbrakk> \<Longrightarrow>
    (p'::'a::len word) + mask n' \<le> p + mask n"
   apply (cases "LENGTH('a) \<le> n")
    apply (frule (1) is_aligned_over_length)
    apply (drule mask_over_length)
    apply clarsimp
   apply (simp add: not_le)
   apply (simp add: word_le_nat_alt unat_plus_simple)
   apply (subst unat_plus_simple[THEN iffD1], erule is_aligned_no_overflow_mask)+
   apply (subst (asm) unat_plus_simple[THEN iffD1], erule is_aligned_no_overflow_mask)
   apply (clarsimp simp: is_aligned_def dvd_def)
   apply (rename_tac k k')
   apply (thin_tac "unat p = x" for p x)+
   apply (subst Suc_le_mono[symmetric])
   apply (simp only: Suc_2p_unat_mask)
   apply (drule le_imp_less_Suc, subst (asm) Suc_2p_unat_mask, assumption)
   apply (erule (1) power_2_mult_step_le)
   done
 
 lemma mask_mono:
   "sz' \<le> sz \<Longrightarrow> mask sz' \<le> (mask sz :: 'a::len word)"
   by (simp add: le_mask_iff shiftr_mask_le)
 
 lemma aligned_mask_disjoint:
   "\<lbrakk> is_aligned (a :: 'a :: len word) n; b \<le> mask n \<rbrakk> \<Longrightarrow> a && b = 0"
   by word_eqI_solve
 
 lemma word_and_or_mask_aligned:
   "\<lbrakk> is_aligned a n; b \<le> mask n \<rbrakk> \<Longrightarrow> a + b = a || b"
   by (simp add: aligned_mask_disjoint word_plus_and_or_coroll)
 
 lemma word_and_or_mask_aligned2:
   \<open>is_aligned b n \<Longrightarrow> a \<le> mask n \<Longrightarrow> a + b = a || b\<close>
   using word_and_or_mask_aligned [of b n a] by (simp add: ac_simps)
   
 lemma is_aligned_ucastI:
   "is_aligned w n \<Longrightarrow> is_aligned (ucast w) n"
   by (clarsimp simp: word_eqI_simps)
 
 lemma ucast_le_maskI:
   "a \<le> mask n \<Longrightarrow> UCAST('a::len \<rightarrow> 'b::len) a \<le> mask n"
   by (metis and_mask_eq_iff_le_mask ucast_and_mask)
 
 lemma ucast_add_mask_aligned:
   "\<lbrakk> a \<le> mask n; is_aligned b n \<rbrakk> \<Longrightarrow> UCAST ('a::len \<rightarrow> 'b::len) (a + b) = ucast a + ucast b"
   by (metis add.commute is_aligned_ucastI ucast_le_maskI ucast_or_distrib word_and_or_mask_aligned)
 
 lemma ucast_shiftl:
   "LENGTH('b) \<le> LENGTH ('a) \<Longrightarrow> UCAST ('a::len \<rightarrow> 'b::len) x << n = ucast (x << n)"
   by word_eqI_solve
 
 lemma ucast_leq_mask:
   "LENGTH('a) \<le> n \<Longrightarrow> ucast (x::'a::len word) \<le> mask n"
   by (clarsimp simp: le_mask_high_bits word_size nth_ucast)
 
 lemma shiftl_inj:
   "\<lbrakk> x << n = y << n; x \<le> mask (LENGTH('a)-n); y \<le> mask (LENGTH('a)-n) \<rbrakk> \<Longrightarrow>
    x = (y :: 'a :: len word)"
   apply word_eqI
   apply (rename_tac n')
   apply (case_tac "LENGTH('a) - n \<le> n'", simp)
   by (metis add.commute add.right_neutral diff_add_inverse le_diff_conv linorder_not_less zero_order(1))
 
 lemma distinct_word_add_ucast_shift_inj:
   "\<lbrakk> p + (UCAST('a::len \<rightarrow> 'b::len) off << n) = p' + (ucast off' << n);
      is_aligned p n'; is_aligned p' n'; n' = n + LENGTH('a); n' < LENGTH('b) \<rbrakk>
    \<Longrightarrow> p' = p \<and> off' = off"
   apply (simp add: word_and_or_mask_aligned le_mask_shiftl_le_mask[where n="LENGTH('a)"]
                    ucast_leq_mask)
   apply (simp add: is_aligned_nth)
   apply (rule conjI; word_eqI)
    apply (metis add.commute test_bit_conj_lt diff_add_inverse le_diff_conv nat_less_le)
   apply (rename_tac i)
   apply (erule_tac x="i+n" in allE)
   apply simp
   done
 
 lemma aligned_add_mask_lessD:
   "\<lbrakk> x + mask n < y; is_aligned x n \<rbrakk> \<Longrightarrow> x < y" for y::"'a::len word"
   by (metis is_aligned_no_overflow' mask_2pm1 order_le_less_trans)
 
 lemma aligned_add_mask_less_eq:
   "\<lbrakk> is_aligned x n; is_aligned y n;  n < LENGTH('a) \<rbrakk> \<Longrightarrow> (x + mask n < y) = (x < y)"
   for y::"'a::len word"
   using aligned_add_mask_lessD is_aligned_add_step_le word_le_not_less by blast
 
 lemma word_upto_Nil:
   "y < x \<Longrightarrow> [x .e. y ::'a::len word] = []"
   by (simp add: upto_enum_red not_le word_less_nat_alt)
 
 lemma word_enum_decomp_elem:
   assumes "[x .e. (y ::'a::len word)] = as @ a # bs"
   shows "x \<le> a \<and> a \<le> y"
 proof -
   have "set as \<subseteq> set [x .e. y] \<and> a \<in> set [x .e. y]"
     using assms by (auto dest: arg_cong[where f=set])
   then show ?thesis by auto
 qed
 
 lemma max_word_not_less[simp]:
    "\<not> max_word < x"
   by (simp add: not_less)
 
 lemma word_enum_prefix:
   "[x .e. (y ::'a::len word)] = as @ a # bs \<Longrightarrow> as = (if x < a then [x .e. a - 1] else [])"
   apply (induct as arbitrary: x; clarsimp)
    apply (case_tac "x < y")
     prefer 2
     apply (case_tac "x = y", simp)
     apply (simp add: not_less)
     apply (drule (1) dual_order.not_eq_order_implies_strict)
     apply (simp add: word_upto_Nil)
    apply (simp add: word_upto_Cons_eq)
   apply (case_tac "x < y")
    prefer 2
    apply (case_tac "x = y", simp)
    apply (simp add: not_less)
    apply (drule (1) dual_order.not_eq_order_implies_strict)
    apply (simp add: word_upto_Nil)
   apply (clarsimp simp: word_upto_Cons_eq)
   apply (frule word_enum_decomp_elem)
   apply clarsimp
   apply (rule conjI)
    prefer 2
    apply (subst word_Suc_le[symmetric]; clarsimp)
   apply (drule meta_spec)
   apply (drule (1) meta_mp)
   apply clarsimp
   apply (rule conjI; clarsimp)
   apply (subst (2) word_upto_Cons_eq)
    apply unat_arith
   apply simp
   done
 
 lemma word_enum_decomp_set:
   "[x .e. (y ::'a::len word)] = as @ a # bs \<Longrightarrow> a \<notin> set as"
   by (metis distinct_append distinct_enum_upto' not_distinct_conv_prefix)
 
 lemma word_enum_decomp:
   assumes "[x .e. (y ::'a::len word)] = as @ a # bs"
   shows "x \<le> a \<and> a \<le> y \<and> a \<notin> set as \<and> (\<forall>z \<in> set as. x \<le> z \<and> z \<le> y)"
 proof -
   from assms
   have "set as \<subseteq> set [x .e. y] \<and> a \<in> set [x .e. y]"
     by (auto dest: arg_cong[where f=set])
   with word_enum_decomp_set[OF assms]
   show ?thesis by auto
 qed
 
 lemma of_nat_unat_le_mask_ucast:
   "\<lbrakk>of_nat (unat t) = w; t \<le> mask LENGTH('a)\<rbrakk> \<Longrightarrow> t = UCAST('a::len \<rightarrow> 'b::len) w"
   by (clarsimp simp: ucast_nat_def ucast_ucast_mask simp flip: and_mask_eq_iff_le_mask)
 
 lemma fold_eq_0_to_bool:
   "(v = 0) = (\<not> to_bool v)"
   by (simp add: to_bool_def)
 
 lemma less_diff_gt0:
   "a < b \<Longrightarrow> (0 :: 'a :: len word) < b - a"
   by unat_arith
 
 lemma unat_plus_gt:
   "unat ((a :: 'a :: len word) + b) \<le> unat a + unat b"
   by (clarsimp simp: unat_plus_if_size)
 
 lemma const_less:
   "\<lbrakk> (a :: 'a :: len word) - 1 < b; a \<noteq> b \<rbrakk> \<Longrightarrow> a < b"
   by (metis less_1_simp word_le_less_eq)
 
 lemma add_mult_aligned_neg_mask:
   \<open>(x + y * m) && ~~(mask n) = (x && ~~(mask n)) + y * m\<close>
   if \<open>m && (2 ^ n - 1) = 0\<close>
   by (metis (no_types, hide_lams)
     add.assoc add.commute add.right_neutral add_uminus_conv_diff
    mask_eq_decr_exp mask_eqs(2) mask_eqs(6) mult.commute mult_zero_left
    subtract_mask(1) that)
 
 lemma unat_of_nat_minus_1:
   "\<lbrakk> n < 2 ^ LENGTH('a); n \<noteq> 0 \<rbrakk> \<Longrightarrow> unat ((of_nat n:: 'a :: len word) - 1) = n - 1"
   by (simp add: unat_eq_of_nat)
 
 lemma word_eq_zeroI:
   "a \<le> a - 1 \<Longrightarrow> a = 0" for a :: "'a :: len word"
   by (simp add: word_must_wrap)
 
 lemma word_add_format:
   "(-1 :: 'a :: len  word) + b + c = b + (c - 1)"
   by simp
 
 lemma upto_enum_word_nth:
   "\<lbrakk> i \<le> j; k \<le> unat (j - i) \<rbrakk> \<Longrightarrow> [i .e. j] ! k = i + of_nat k"
   apply (clarsimp simp: upto_enum_def nth_append)
   apply (clarsimp simp: word_le_nat_alt[symmetric])
   apply (rule conjI, clarsimp)
    apply (subst toEnum_of_nat, unat_arith)
    apply unat_arith
   apply (clarsimp simp: not_less unat_sub[symmetric])
   apply unat_arith
   done
 
 lemma upto_enum_step_nth:
   "\<lbrakk> a \<le> c; n \<le> unat ((c - a) div (b - a)) \<rbrakk>
    \<Longrightarrow> [a, b .e. c] ! n = a + of_nat n * (b - a)"
   by (clarsimp simp: upto_enum_step_def not_less[symmetric] upto_enum_word_nth)
 
 lemma upto_enum_inc_1_len:
   "a < - 1 \<Longrightarrow> [(0 :: 'a :: len word) .e. 1 + a] = [0 .e. a] @ [1 + a]"
   apply (simp add: upto_enum_word)
   apply (subgoal_tac "unat (1+a) = 1 + unat a")
    apply simp
   apply (subst unat_plus_simple[THEN iffD1])
    apply (metis add.commute no_plus_overflow_neg olen_add_eqv)
   apply unat_arith
   done
 
 lemma neg_mask_add:
   "y && mask n = 0 \<Longrightarrow> x + y && ~~(mask n) = (x && ~~(mask n)) + y"
   by (clarsimp simp: mask_out_sub_mask mask_eqs(7)[symmetric] mask_twice)
 
 lemma shiftr_shiftl_shiftr[simp]:
   "(x :: 'a :: len word)  >> a << a >> a = x >> a"
   by word_eqI_solve
 
 lemma add_right_shift:
   "\<lbrakk> x && mask n = 0; y && mask n = 0; x \<le> x + y \<rbrakk>
    \<Longrightarrow> (x + y :: ('a :: len) word) >> n = (x >> n) + (y >> n)"
   apply (simp add: no_olen_add_nat is_aligned_mask[symmetric])
   apply (simp add: unat_arith_simps shiftr_div_2n' split del: if_split)
   apply (subst if_P)
    apply (erule order_le_less_trans[rotated])
    apply (simp add: add_mono)
   apply (simp add: shiftr_div_2n' is_aligned_def)
   done
 
 lemma sub_right_shift:
   "\<lbrakk> x && mask n = 0; y && mask n = 0; y \<le> x \<rbrakk>
    \<Longrightarrow> (x - y) >> n = (x >> n :: 'a :: len word) - (y >> n)"
   using add_right_shift[where x="x - y" and y=y and n=n]
   by (simp add: aligned_sub_aligned is_aligned_mask[symmetric] word_sub_le)
 
 lemma and_and_mask_simple:
   "y && mask n = mask n \<Longrightarrow> (x && y) && mask n = x && mask n"
   by (simp add: ac_simps)
 
 lemma and_and_mask_simple_not:
   "y && mask n = 0 \<Longrightarrow> (x && y) && mask n = 0"
   by (simp add: ac_simps)
 
 lemma word_and_le':
   "b \<le> c \<Longrightarrow> (a :: 'a :: len word) && b \<le> c"
   by (metis word_and_le1 order_trans)
 
 lemma word_and_less':
   "b < c \<Longrightarrow> (a :: 'a :: len word) && b < c"
   by (metis word_and_le1 xtr7)
 
 lemma shiftr_w2p:
   "x < LENGTH('a) \<Longrightarrow> 2 ^ x = (2 ^ (LENGTH('a) - 1) >> (LENGTH('a) - 1 - x) :: 'a :: len word)"
   by word_eqI_solve
 
 lemma t2p_shiftr:
   "\<lbrakk> b \<le> a; a < LENGTH('a) \<rbrakk> \<Longrightarrow> (2 :: 'a :: len word) ^ a >> b = 2 ^ (a - b)"
   by word_eqI_solve
 
 lemma scast_1[simp]:
   "scast (1 :: 'a :: len signed word) = (1 :: 'a word)"
   by simp
 
 lemma ucast_ucast_mask_eq:
   "\<lbrakk> UCAST('a::len \<rightarrow> 'b::len) x = y; x && mask LENGTH('b) = x \<rbrakk> \<Longrightarrow> x = ucast y"
   by word_eqI_solve
 
 lemma ucast_up_eq:
   "\<lbrakk> ucast x = (ucast y::'b::len word); LENGTH('a) \<le> LENGTH ('b) \<rbrakk>
    \<Longrightarrow> ucast x = (ucast y::'a::len word)"
   by word_eqI_solve
 
 lemma ucast_up_neq:
   "\<lbrakk> ucast x \<noteq> (ucast y::'b::len word); LENGTH('b) \<le> LENGTH ('a) \<rbrakk>
    \<Longrightarrow> ucast x \<noteq> (ucast y::'a::len word)"
   by (fastforce dest: ucast_up_eq)
 
 lemma mask_AND_less_0:
   "\<lbrakk> x && mask n = 0; m \<le> n \<rbrakk> \<Longrightarrow> x && mask m = 0"
   by (metis mask_twice2 word_and_notzeroD)
 
 lemma mask_len_id [simp]:
   "(x :: 'a :: len word) && mask LENGTH('a) = x"
   using uint_lt2p [of x] by (simp add: mask_eq_iff)
 
 lemma scast_ucast_down_same:
   "LENGTH('b) \<le> LENGTH('a) \<Longrightarrow> SCAST('a \<rightarrow> 'b) = UCAST('a::len \<rightarrow> 'b::len)"
   by (simp add: down_cast_same is_down)
 
 lemma word_aligned_0_sum:
   "\<lbrakk> a + b = 0; is_aligned (a :: 'a :: len word) n; b \<le> mask n; n < LENGTH('a) \<rbrakk>
    \<Longrightarrow> a = 0 \<and> b = 0"
   by (simp add: word_plus_and_or_coroll aligned_mask_disjoint word_or_zero)
 
 lemma mask_eq1_nochoice:
   "\<lbrakk> LENGTH('a) > 1; (x :: 'a :: len word) && 1 = x \<rbrakk> \<Longrightarrow> x = 0 \<or> x = 1"
   by (metis word_and_1)
 
 lemma pow_mono_leq_imp_lt:
   "x \<le> y \<Longrightarrow> x < 2 ^ y"
   by (simp add: le_less_trans)
 
 lemma unat_of_nat_ctz_mw:
   "unat (of_nat (word_ctz (w :: 'a :: len word)) :: 'a :: len word) = word_ctz w"
   using word_ctz_le[where w=w, simplified] unat_of_nat_eq[where x="word_ctz w" and 'a="'a"]
         pow_mono_leq_imp_lt
   by simp
 
 lemma unat_of_nat_ctz_smw:
   "unat (of_nat (word_ctz (w :: 'a :: len word)) :: 'a :: len sword) = word_ctz w"
   using word_ctz_le[where w=w, simplified] unat_of_nat_eq[where x="word_ctz w" and 'a="'a"]
         pow_mono_leq_imp_lt
   by (metis le_unat_uoi le_unat_uoi linorder_neqE_nat nat_less_le scast_of_nat
             word_unat.Rep_inverse)
 
 lemma shiftr_and_eq_shiftl:
   "(w >> n) && x = y \<Longrightarrow> w && (x << n) = (y << n)" for y :: "'a:: len word"
   by (metis (no_types, lifting) and_not_mask bit.conj_ac(1) bit.conj_ac(2) mask_eq_0_eq_x shiftl_mask_is_0 shiftl_over_and_dist)
 
 lemma neg_mask_combine:
   "~~(mask a) && ~~(mask b) = ~~(mask (max a b))"
   by (auto simp: word_ops_nth_size word_size intro!: word_eqI)
 
 lemma neg_mask_twice:
   "x && ~~(mask n) && ~~(mask m) = x && ~~(mask (max n m))"
   by (metis neg_mask_combine)
 
 lemma multiple_mask_trivia:
   "n \<ge> m \<Longrightarrow> (x && ~~(mask n)) + (x && mask n && ~~(mask m)) = x && ~~(mask m)"
   apply (rule trans[rotated], rule_tac w="mask n" in word_plus_and_or_coroll2)
   apply (simp add: word_bw_assocs word_bw_comms word_bw_lcs neg_mask_twice
                    max_absorb2)
   done
 
 lemma add_mask_lower_bits':
   "\<lbrakk> len = LENGTH('a); is_aligned (x :: 'a :: len word) n;
      \<forall>n' \<ge> n. n' < len \<longrightarrow> \<not> p !! n' \<rbrakk>
    \<Longrightarrow> x + p && ~~(mask n) = x"
   using add_mask_lower_bits by auto
 
 lemma neg_mask_in_mask_range:
   "is_aligned ptr bits \<Longrightarrow> (ptr' && ~~(mask bits) = ptr) = (ptr' \<in> mask_range ptr bits)"
   apply (erule is_aligned_get_word_bits)
    apply (rule iffI)
     apply (drule sym)
     apply (simp add: word_and_le2)
     apply (subst word_plus_and_or_coroll, word_eqI_solve)
     apply (metis le_word_or2 neg_mask_add_mask and.right_idem)
    apply clarsimp
    apply (smt add.right_neutral eq_iff is_aligned_neg_mask_eq mask_out_add_aligned neg_mask_mono_le
               word_and_not)
   apply (simp add: power_overflow mask_eq_decr_exp)
   done
 
 lemma aligned_offset_in_range:
   "\<lbrakk> is_aligned (x :: 'a :: len word) m; y < 2 ^ m; is_aligned p n; n \<ge> m; n < LENGTH('a) \<rbrakk>
    \<Longrightarrow> (x + y \<in> {p .. p + mask n}) = (x \<in> mask_range p n)"
   apply (simp only: is_aligned_add_or flip: neg_mask_in_mask_range)
   by (metis less_mask_eq mask_subsume)
 
 lemma mask_range_to_bl':
   "\<lbrakk> is_aligned (ptr :: 'a :: len word) bits; bits < LENGTH('a) \<rbrakk>
    \<Longrightarrow> mask_range ptr bits
        = {x. take (LENGTH('a) - bits) (to_bl x) = take (LENGTH('a) - bits) (to_bl ptr)}"
   apply (rule set_eqI, rule iffI)
    apply clarsimp
    apply (subgoal_tac "\<exists>y. x = ptr + y \<and> y < 2 ^ bits")
     apply clarsimp
     apply (subst is_aligned_add_conv)
        apply assumption
       apply simp
     apply simp
    apply (rule_tac x="x - ptr" in exI)
    apply (simp add: add_diff_eq[symmetric])
    apply (simp only: word_less_sub_le[symmetric])
    apply (rule word_diff_ls')
     apply (simp add: field_simps mask_eq_decr_exp)
    apply assumption
   apply simp
   apply (subgoal_tac "\<exists>y. y < 2 ^ bits \<and> to_bl (ptr + y) = to_bl x")
    apply clarsimp
    apply (rule conjI)
     apply (erule(1) is_aligned_no_wrap')
    apply (simp only: add_diff_eq[symmetric] mask_eq_decr_exp)
    apply (rule word_plus_mono_right)
     apply simp
    apply (erule is_aligned_no_wrap')
    apply simp
   apply (rule_tac x="of_bl (drop (LENGTH('a) - bits) (to_bl x))" in exI)
   apply (rule context_conjI)
    apply (rule order_less_le_trans [OF of_bl_length])
     apply simp
    apply simp
   apply (subst is_aligned_add_conv)
      apply assumption
     apply simp
   apply (drule sym)
   apply (simp add: word_rep_drop)
   done
 
 lemma mask_range_to_bl:
   "is_aligned (ptr :: 'a :: len word) bits
    \<Longrightarrow> mask_range ptr bits
         = {x. take (LENGTH('a) - bits) (to_bl x) = take (LENGTH('a) - bits) (to_bl ptr)}"
   apply (erule is_aligned_get_word_bits)
    apply (erule(1) mask_range_to_bl')
   apply (rule set_eqI)
   apply (simp add: power_overflow mask_eq_decr_exp)
   done
 
 lemma aligned_mask_range_cases:
   "\<lbrakk> is_aligned (p :: 'a :: len word) n; is_aligned (p' :: 'a :: len word) n' \<rbrakk>
    \<Longrightarrow> mask_range p n \<inter> mask_range p' n' = {} \<or>
        mask_range p n \<subseteq> mask_range p' n' \<or>
        mask_range p n \<supseteq> mask_range p' n'"
   apply (simp add: mask_range_to_bl)
   apply (rule Meson.disj_comm, rule disjCI)
   apply (erule nonemptyE)
   apply simp
   apply (subgoal_tac "(\<exists>n''. LENGTH('a) - n = (LENGTH('a) - n') + n'')
                     \<or> (\<exists>n''. LENGTH('a) - n' = (LENGTH('a) - n) + n'')")
    apply (fastforce simp: take_add)
   apply arith
   done
 
 lemma aligned_mask_range_offset_subset:
   assumes al: "is_aligned (ptr :: 'a :: len word) sz" and al': "is_aligned x sz'"
   and szv: "sz' \<le> sz"
   and xsz: "x < 2 ^ sz"
   shows "mask_range (ptr+x) sz' \<subseteq> mask_range ptr sz"
   using al
 proof (rule is_aligned_get_word_bits)
   assume p0: "ptr = 0" and szv': "LENGTH ('a) \<le> sz"
   then have "(2 ::'a word) ^ sz = 0" by simp
   show ?thesis using p0
     by (simp add: \<open>2 ^ sz = 0\<close> mask_eq_decr_exp)
 next
   assume szv': "sz < LENGTH('a)"
 
   hence blah: "2 ^ (sz - sz') < (2 :: nat) ^ LENGTH('a)"
     using szv by auto
   show ?thesis using szv szv'
     apply (intro range_subsetI)
      apply (rule is_aligned_no_wrap' [OF al xsz])
     apply (simp only: flip: add_diff_eq add_mask_fold)
     apply (subst add.assoc, rule word_plus_mono_right)
      using al' is_aligned_add_less_t2n xsz
      apply fastforce
     apply (simp add: field_simps szv al is_aligned_no_overflow)
     done
 qed
 
 lemma aligned_mask_diff:
   "\<lbrakk> is_aligned (dest :: 'a :: len word) bits; is_aligned (ptr :: 'a :: len word) sz;
      bits \<le> sz; sz < LENGTH('a); dest < ptr \<rbrakk>
    \<Longrightarrow> mask bits + dest < ptr"
   apply (frule_tac p' = ptr in aligned_mask_range_cases, assumption)
   apply (elim disjE)
     apply (drule_tac is_aligned_no_overflow_mask, simp)+
     apply (simp add: algebra_split_simps word_le_not_less)
    apply (drule is_aligned_no_overflow_mask; fastforce)
   by (simp add: aligned_add_mask_less_eq is_aligned_weaken algebra_split_simps)
 
 lemma aligned_mask_ranges_disjoint:
   "\<lbrakk> is_aligned (p :: 'a :: len word) n; is_aligned (p' :: 'a :: len word) n';
      p && ~~(mask n') \<noteq> p'; p' && ~~(mask n) \<noteq> p \<rbrakk>
    \<Longrightarrow> mask_range p n \<inter> mask_range p' n' = {}"
   using aligned_mask_range_cases
   by (auto simp: neg_mask_in_mask_range)
 
 lemma aligned_mask_ranges_disjoint2:
   "\<lbrakk> is_aligned p n; is_aligned ptr bits; n \<ge> m; n < size p; m \<le> bits;
      (\<forall>y < 2 ^ (n - m). p + (y << m) \<notin> mask_range ptr bits) \<rbrakk>
    \<Longrightarrow> mask_range p n \<inter> mask_range ptr bits = {}"
   apply safe
   apply (simp only: flip: neg_mask_in_mask_range)
   apply (drule_tac x="x && mask n >> m" in spec)
   apply (clarsimp simp: shiftr_less_t2n and_mask_less_size wsst_TYs multiple_mask_trivia
                         word_bw_assocs neg_mask_twice max_absorb2 shiftr_shiftl1)
   done
 
 lemma leq_mask_shift:
   "(x :: 'a :: len word) \<le> mask (low_bits + high_bits) \<Longrightarrow> (x >> low_bits) \<le> mask high_bits"
   by (simp add: le_mask_iff shiftr_shiftr)
 
 lemma ucast_ucast_eq_mask_shift:
   "(x :: 'a :: len word) \<le> mask (low_bits + LENGTH('b))
    \<Longrightarrow> ucast((ucast (x >> low_bits)) :: 'b :: len word) = x >> low_bits"
   by (meson and_mask_eq_iff_le_mask eq_ucast_ucast_eq not_le_imp_less shiftr_less_t2n'
             ucast_ucast_len)
 
 lemma const_le_unat:
   "\<lbrakk> b < 2 ^ LENGTH('a); of_nat b \<le> a \<rbrakk> \<Longrightarrow> b \<le> unat (a :: 'a :: len word)"
   apply (simp add: word_le_def)
   apply (simp only: uint_nat zle_int)
   apply transfer
   apply (simp add: take_bit_nat_eq_self)
   done
 
 lemma upt_enum_offset_trivial:
   "\<lbrakk> x < 2 ^ LENGTH('a) - 1 ; n \<le> unat x \<rbrakk>
    \<Longrightarrow> ([(0 :: 'a :: len word) .e. x] ! n) = of_nat n"
   apply (induct x arbitrary: n)
     apply simp
   by (simp add: upto_enum_word_nth)
 
 lemma word_le_mask_out_plus_2sz:
   "x \<le> (x && ~~(mask sz)) + 2 ^ sz - 1"
   by (metis add_diff_eq word_neg_and_le)
 
 lemma ucast_add:
   "ucast (a + (b :: 'a :: len word)) = ucast a + (ucast b :: ('a signed word))"
   by transfer (simp add: take_bit_add)
 
 lemma ucast_minus:
   "ucast (a - (b :: 'a :: len word)) = ucast a - (ucast b :: ('a signed word))"
   apply (insert ucast_add[where a=a and b="-b"])
   apply (metis (no_types, hide_lams) add_diff_eq diff_add_cancel ucast_add)
   done
 
 lemma scast_ucast_add_one [simp]:
   "scast (ucast (x :: 'a::len word) + (1 :: 'a signed word)) = x + 1"
   apply (subst ucast_1[symmetric])
   apply (subst ucast_add[symmetric])
   apply clarsimp
   done
 
 lemma word_and_le_plus_one:
   "a > 0 \<Longrightarrow> (x :: 'a :: len word) && (a - 1) < a"
   by (simp add: gt0_iff_gem1 word_and_less')
 
 lemma unat_of_ucast_then_shift_eq_unat_of_shift[simp]:
   "LENGTH('b) \<ge> LENGTH('a)
    \<Longrightarrow> unat ((ucast (x :: 'a :: len word) :: 'b :: len word) >> n) = unat (x >> n)"
   by (simp add: shiftr_div_2n' unat_ucast_up_simp)
 
 lemma unat_of_ucast_then_mask_eq_unat_of_mask[simp]:
   "LENGTH('b) \<ge> LENGTH('a)
    \<Longrightarrow> unat ((ucast (x :: 'a :: len word) :: 'b :: len word) && mask m) = unat (x && mask m)"
   by (metis ucast_and_mask unat_ucast_up_simp)
 
 lemma small_powers_of_2:
   "x \<ge> 3 \<Longrightarrow> x < 2 ^ (x - 1)"
   by (induct x; simp add: suc_le_pow_2)
 
 lemma word_clz_sint_upper[simp]:
   "LENGTH('a) \<ge> 3 \<Longrightarrow> sint (of_nat (word_clz (w :: 'a :: len word)) :: 'a sword) \<le> int (LENGTH('a))"
   using small_powers_of_2
   by (smt One_nat_def diff_less le_less_trans len_gt_0 len_signed lessI n_less_equal_power_2
            not_msb_from_less of_nat_mono sint_eq_uint uint_nat unat_of_nat_eq unat_power_lower
            word_clz_max word_of_nat_less wsst_TYs(3))
 
 lemma word_clz_sint_lower[simp]:
   "LENGTH('a) \<ge> 3
    \<Longrightarrow> - sint (of_nat (word_clz (w :: 'a :: len word)) :: 'a signed word) \<le> int (LENGTH('a))"
   apply (subst sint_eq_uint)
    using small_powers_of_2 uint_nat
    apply (simp add: order_le_less_trans[OF word_clz_max] not_msb_from_less word_of_nat_less
                     word_size)
   by (simp add: uint_nat)
 
 lemma shiftr_less_t2n3:
   "\<lbrakk> (2 :: 'a word) ^ (n + m) = 0; m < LENGTH('a) \<rbrakk>
    \<Longrightarrow> (x :: 'a :: len word) >> n < 2 ^ m"
   by (fastforce intro: shiftr_less_t2n' simp: mask_eq_decr_exp power_overflow)
 
 lemma unat_shiftr_le_bound:
   "\<lbrakk> 2 ^ (LENGTH('a :: len) - n) - 1 \<le> bnd; 0 < n \<rbrakk>
    \<Longrightarrow> unat ((x :: 'a word) >> n) \<le> bnd"
   using less_not_refl3 le_step_down_nat le_trans less_or_eq_imp_le word_shiftr_lt
   by (metis (no_types, lifting))
 
 lemma shiftr_eqD:
   "\<lbrakk> x >> n = y >> n; is_aligned x n; is_aligned y n \<rbrakk>
    \<Longrightarrow> x = y"
   by (metis is_aligned_shiftr_shiftl)
 
 lemma word_shiftr_shiftl_shiftr_eq_shiftr:
   "a \<ge> b \<Longrightarrow> (x :: 'a :: len word) >> a << b >> b = x >> a"
   by (simp add: mask_shift multi_shift_simps(5) shiftr_shiftr)
 
 lemma of_int_uint_ucast:
    "of_int (uint (x :: 'a::len word)) = (ucast x :: 'b::len word)"
   by (fact Word.of_int_uint)
 
 lemma mod_mask_drop:
   "\<lbrakk> m = 2 ^ n; 0 < m; mask n && msk = mask n \<rbrakk>
    \<Longrightarrow> (x mod m) && msk = x mod m"
   by (simp add: word_mod_2p_is_mask word_bw_assocs)
 
 lemma mask_eq_ucast_eq:
   "\<lbrakk> x && mask LENGTH('a) = (x :: ('c :: len word));
      LENGTH('a) \<le> LENGTH('b)\<rbrakk>
     \<Longrightarrow> ucast (ucast x :: ('a :: len word)) = (ucast x :: ('b :: len word))"
   by (metis ucast_and_mask ucast_id ucast_ucast_mask ucast_up_eq)
 
 lemma of_nat_less_t2n:
   "of_nat i < (2 :: ('a :: len) word) ^ n \<Longrightarrow> n < LENGTH('a) \<and> unat (of_nat i :: 'a word) < 2 ^ n"
   by (metis order_less_trans p2_gt_0 unat_less_power word_neq_0_conv)
 
 lemma two_power_increasing_less_1:
   "\<lbrakk> n \<le> m; m \<le> LENGTH('a) \<rbrakk> \<Longrightarrow> (2 :: 'a :: len word) ^ n - 1 \<le> 2 ^ m - 1"
   by (metis diff_diff_cancel le_m1_iff_lt less_imp_diff_less p2_gt_0 two_power_increasing
             word_1_le_power word_le_minus_mono_left word_less_sub_1)
 
 lemma word_sub_mono4:
   "\<lbrakk> y + x \<le> z + x; y \<le> y + x; z \<le> z + x \<rbrakk> \<Longrightarrow> y \<le> z" for y :: "'a :: len word"
   by (simp add: word_add_le_iff2)
 
 lemma eq_or_less_helperD:
   "\<lbrakk> n = unat (2 ^ m - 1 :: 'a :: len word) \<or> n < unat (2 ^ m - 1 :: 'a word); m < LENGTH('a) \<rbrakk>
    \<Longrightarrow> n < 2 ^ m"
   by (meson le_less_trans nat_less_le unat_less_power word_power_less_1)
 
 lemma mask_sub:
   "n \<le> m \<Longrightarrow> mask m - mask n = mask m && ~~(mask n)"
   by (metis (full_types) and_mask_eq_iff_shiftr_0 mask_out_sub_mask shiftr_mask_le word_bw_comms(1))
 
 lemma neg_mask_diff_bound:
   "sz'\<le> sz \<Longrightarrow> (ptr && ~~(mask sz')) - (ptr && ~~(mask sz)) \<le> 2 ^ sz - 2 ^ sz'"
   (is "_ \<Longrightarrow> ?lhs \<le> ?rhs")
 proof -
   assume lt: "sz' \<le> sz"
   hence "?lhs = ptr && (mask sz && ~~(mask sz'))"
     by (metis add_diff_cancel_left' multiple_mask_trivia)
   also have "\<dots> \<le> ?rhs" using lt
     by (metis (mono_tags) add_diff_eq diff_eq_eq eq_iff mask_2pm1 mask_sub word_and_le')
   finally show ?thesis by simp
 qed
 
 lemma mask_range_subsetD:
   "\<lbrakk> p' \<in> mask_range p n; x' \<in> mask_range p' n'; n' \<le> n; is_aligned p n; is_aligned p' n' \<rbrakk> \<Longrightarrow>
    x' \<in> mask_range p n"
   using aligned_mask_step by fastforce
 
 lemma add_mult_in_mask_range:
   "\<lbrakk> is_aligned (base :: 'a :: len word) n; n < LENGTH('a); bits \<le> n; x < 2 ^ (n - bits) \<rbrakk>
    \<Longrightarrow> base + x * 2^bits \<in> mask_range base n"
   by (simp add: is_aligned_no_wrap' mask_2pm1 nasty_split_lt word_less_power_trans2
                 word_plus_mono_right)
 
 lemma of_bl_length2:
   "length xs + c < LENGTH('a) \<Longrightarrow> of_bl xs * 2^c < (2::'a::len word) ^ (length xs + c)"
   by (simp add: of_bl_length word_less_power_trans2)
 
 lemma mask_out_eq_0:
   "\<lbrakk> idx < 2 ^ sz; sz < LENGTH('a) \<rbrakk> \<Longrightarrow> (of_nat idx :: 'a :: len word) && ~~(mask sz) = 0"
   by (simp add: Word_Lemmas.of_nat_power less_mask_eq mask_eq_0_eq_x)
 
 lemma is_aligned_neg_mask_eq':
   "is_aligned ptr sz = (ptr && ~~(mask sz) = ptr)"
   using is_aligned_mask mask_eq_0_eq_x by blast
 
 lemma neg_mask_mask_unat:
   "sz < LENGTH('a)
    \<Longrightarrow> unat ((ptr :: 'a :: len word) && ~~(mask sz)) + unat (ptr && mask sz) = unat ptr"
   by (metis AND_NOT_mask_plus_AND_mask_eq unat_plus_simple word_and_le2)
 
 lemma unat_pow_le_intro:
   "LENGTH('a) \<le> n \<Longrightarrow> unat (x :: 'a :: len word) < 2 ^ n"
   by (metis lt2p_lem not_le of_nat_le_iff of_nat_numeral semiring_1_class.of_nat_power uint_nat)
 
 lemma unat_shiftl_less_t2n:
   "\<lbrakk> unat (x :: 'a :: len word) < 2 ^ (m - n); m < LENGTH('a) \<rbrakk> \<Longrightarrow> unat (x << n) < 2 ^ m"
   by (metis (no_types) Word_Lemmas.of_nat_power diff_le_self le_less_trans shiftl_less_t2n
                        unat_less_power word_unat.Rep_inverse)
 
 lemma unat_is_aligned_add:
   "\<lbrakk> is_aligned p n; unat d < 2 ^ n \<rbrakk>
    \<Longrightarrow> unat (p + d && mask n) = unat d \<and> unat (p + d && ~~(mask n)) = unat p"
   by (metis add.right_neutral and_mask_eq_iff_le_mask and_not_mask le_mask_iff mask_add_aligned
             mask_out_add_aligned mult_zero_right shiftl_t2n shiftr_le_0)
 
 lemma unat_shiftr_shiftl_mask_zero:
   "\<lbrakk> c + a \<ge> LENGTH('a) + b ; c < LENGTH('a) \<rbrakk>
    \<Longrightarrow> unat (((q :: 'a :: len word) >> a << b) && ~~(mask c)) = 0"
   by (fastforce intro: unat_is_aligned_add[where p=0 and n=c, simplified, THEN conjunct2]
                        unat_shiftl_less_t2n unat_shiftr_less_t2n unat_pow_le_intro)
 
 lemmas of_nat_ucast = ucast_of_nat[symmetric]
 
 lemma shift_then_mask_eq_shift_low_bits:
   "x \<le> mask (low_bits + high_bits) \<Longrightarrow> (x >> low_bits) && mask high_bits = x >> low_bits"
   by (simp add: leq_mask_shift le_mask_imp_and_mask)
 
 lemma leq_low_bits_iff_zero:
   "\<lbrakk> x \<le> mask (low bits + high bits); x >> low_bits = 0 \<rbrakk> \<Longrightarrow> (x && mask low_bits = 0) = (x = 0)"
   using and_mask_eq_iff_shiftr_0 by force
 
 lemma unat_less_iff:
   "\<lbrakk> unat (a :: 'a :: len word) = b; c < 2 ^ LENGTH('a) \<rbrakk> \<Longrightarrow> (a < of_nat c) = (b < c)"
   using unat_ucast_less_no_overflow_simp by blast
 
 lemma is_aligned_no_overflow3:
  "\<lbrakk> is_aligned (a :: 'a :: len word) n; n < LENGTH('a); b < 2 ^ n; c \<le> 2 ^ n; b < c \<rbrakk>
   \<Longrightarrow> a + b \<le> a + (c - 1)"
   by (meson is_aligned_no_wrap' le_m1_iff_lt not_le word_less_sub_1 word_plus_mono_right)
 
 lemma mask_add_aligned_right:
   "is_aligned p n \<Longrightarrow> (q + p) && mask n = q && mask n"
   by (simp add: mask_add_aligned add.commute)
 
 lemma leq_high_bits_shiftr_low_bits_leq_bits_mask:
   "x \<le> mask high_bits \<Longrightarrow> (x :: 'a :: len word) << low_bits \<le> mask (low_bits + high_bits)"
   by (metis le_mask_shiftl_le_mask)
 
 lemma from_to_bool_last_bit:
   "from_bool (to_bool (x && 1)) = x && 1"
   by (metis from_bool_to_bool_iff word_and_1)
 
 lemma word_two_power_neg_ineq:
   "2 ^ m \<noteq> (0 :: 'a word) \<Longrightarrow> 2 ^ n \<le> - (2 ^ m :: 'a :: len word)"
   apply (cases "n < LENGTH('a)"; simp add: power_overflow)
   apply (cases "m < LENGTH('a)"; simp add: power_overflow)
   apply (simp add: word_le_nat_alt unat_minus word_size)
   apply (cases "LENGTH('a)"; simp)
   apply (simp add: less_Suc_eq_le)
   apply (drule power_increasing[where a=2 and n=n] power_increasing[where a=2 and n=m], simp)+
   apply (drule(1) add_le_mono)
   apply simp
   done
 
 lemma unat_shiftl_absorb:
   "\<lbrakk> x \<le> 2 ^ p; p + k < LENGTH('a) \<rbrakk> \<Longrightarrow> unat (x :: 'a :: len word) * 2 ^ k = unat (x * 2 ^ k)"
   by (smt add_diff_cancel_right' add_lessD1 le_add2 le_less_trans mult.commute nat_le_power_trans
           unat_lt2p unat_mult_lem unat_power_lower word_le_nat_alt)
 
 lemma word_plus_mono_right_split:
   "\<lbrakk> unat ((x :: 'a :: len word) && mask sz) + unat z < 2 ^ sz; sz < LENGTH('a) \<rbrakk>
    \<Longrightarrow> x \<le> x + z"
   apply (subgoal_tac "(x && ~~(mask sz)) + (x && mask sz) \<le> (x && ~~(mask sz)) + ((x && mask sz) + z)")
    apply (simp add:word_plus_and_or_coroll2 field_simps)
   apply (rule word_plus_mono_right)
    apply (simp add: less_le_trans no_olen_add_nat)
   using Word_Lemmas.of_nat_power is_aligned_no_wrap' by force
 
 lemma mul_not_mask_eq_neg_shiftl:
   "~~(mask n) = -1 << n"
   by (simp add: NOT_mask shiftl_t2n)
 
 lemma shiftr_mul_not_mask_eq_and_not_mask:
   "(x >> n) * ~~(mask n) = - (x && ~~(mask n))"
   by (metis NOT_mask and_not_mask mult_minus_left semiring_normalization_rules(7) shiftl_t2n)
 
 lemma mask_eq_n1_shiftr:
   "n \<le> LENGTH('a) \<Longrightarrow> (mask n :: 'a :: len word) = -1 >> (LENGTH('a) - n)"
   by (metis diff_diff_cancel eq_refl mask_full shiftr_mask2)
 
 lemma is_aligned_mask_out_add_eq:
   "is_aligned p n \<Longrightarrow> (p + x) && ~~(mask n) = p + (x && ~~(mask n))"
   by (simp add: mask_out_sub_mask mask_add_aligned)
 
 lemmas is_aligned_mask_out_add_eq_sub
     = is_aligned_mask_out_add_eq[where x="a - b" for a b, simplified field_simps]
 
 lemma aligned_bump_down:
   "is_aligned x n \<Longrightarrow> (x - 1) && ~~(mask n) = x - 2 ^ n"
   by (drule is_aligned_mask_out_add_eq[where x="-1"]) (simp add: NOT_mask)
 
 lemma unat_2tp_if:
   "unat (2 ^ n :: ('a :: len) word) = (if n < LENGTH ('a) then 2 ^ n else 0)"
   by (split if_split, simp_all add: power_overflow)
 
 lemma mask_of_mask:
   "mask (n::nat) && mask (m::nat) = mask (min m n)"
   by word_eqI_solve
 
 lemma unat_signed_ucast_less_ucast:
   "LENGTH('a) \<le> LENGTH('b) \<Longrightarrow> unat (ucast (x :: 'a :: len word) :: 'b :: len signed word) = unat x"
   by (simp add: unat_ucast_up_simp)
 
 lemma toEnum_of_ucast:
   "LENGTH('b) \<le> LENGTH('a) \<Longrightarrow>
    (toEnum (unat (b::'b :: len word))::'a :: len word) = of_nat (unat b)"
   by (simp add: unat_pow_le_intro)
 
 lemmas unat_ucast_mask = unat_ucast_eq_unat_and_mask[where w=a for a]
 
 lemma t2n_mask_eq_if:
   "2 ^ n && mask m = (if n < m then 2 ^ n else 0)"
   by (rule word_eqI, auto simp add: word_size nth_w2p split: if_split)
 
 lemma unat_ucast_le:
   "unat (ucast (x :: 'a :: len word) :: 'b :: len word) \<le> unat x"
   by (simp add: ucast_nat_def word_unat_less_le)
 
 lemma ucast_le_up_down_iff:
   "\<lbrakk> LENGTH('a) \<le> LENGTH('b); (x :: 'b :: len word) \<le> ucast (max_word :: 'a :: len word) \<rbrakk>
    \<Longrightarrow> (ucast x \<le> (y :: 'a word)) = (x \<le> ucast y)"
   using le_max_word_ucast_id ucast_le_ucast by metis
 
 lemma ucast_ucast_mask_shift:
   "a \<le> LENGTH('a) + b
    \<Longrightarrow> ucast (ucast (p && mask a >> b) :: 'a :: len word) = p && mask a >> b"
   by (metis add.commute le_mask_iff shiftr_mask_le ucast_ucast_eq_mask_shift word_and_le')
 
 lemma unat_ucast_mask_shift:
   "a \<le> LENGTH('a) + b
    \<Longrightarrow> unat (ucast (p && mask a >> b) :: 'a :: len word) = unat (p && mask a >> b)"
   by (metis linear ucast_ucast_mask_shift unat_ucast_up_simp)
 
 lemma mask_overlap_zero:
   "a \<le> b \<Longrightarrow> (p && mask a) && ~~(mask b) = 0"
   by (metis NOT_mask_AND_mask mask_lower_twice2 max_def)
 
 lemma mask_shifl_overlap_zero:
   "a + c \<le> b \<Longrightarrow> (p && mask a << c) && ~~(mask b) = 0"
   by (metis and_mask_0_iff_le_mask mask_mono mask_shiftl_decompose order_trans shiftl_over_and_dist word_and_le' word_and_le2)
 
 lemma mask_overlap_zero':
   "a \<ge> b \<Longrightarrow> (p && ~~(mask a)) && mask b = 0"
   using mask_AND_NOT_mask mask_AND_less_0 by blast
 
 lemma mask_rshift_mult_eq_rshift_lshift:
   "((a :: 'a :: len word) >> b) * (1 << c) = (a >> b << c)"
   by (simp add: shiftl_t2n)
 
 lemma shift_alignment:
   "a \<ge> b \<Longrightarrow> is_aligned (p >> a << a) b"
   using is_aligned_shift is_aligned_weaken by blast
 
 lemma mask_split_sum_twice:
   "a \<ge> b \<Longrightarrow> (p && ~~(mask a)) + ((p && mask a) && ~~(mask b)) + (p && mask b) = p"
   by (simp add: add.commute multiple_mask_trivia word_bw_comms(1) word_bw_lcs(1) word_plus_and_or_coroll2)
 
 lemma mask_shift_eq_mask_mask:
   "(p && mask a >> b << b) = (p && mask a) && ~~(mask b)"
   by (simp add: and_not_mask)
 
 lemma mask_shift_sum:
   "\<lbrakk> a \<ge> b; unat n = unat (p && mask b) \<rbrakk>
    \<Longrightarrow> (p && ~~(mask a)) + (p && mask a >> b) * (1 << b) + n = (p :: 'a :: len word)"
   by (metis and_not_mask mask_rshift_mult_eq_rshift_lshift mask_split_sum_twice word_unat.Rep_eqD)
 
 lemma is_up_compose:
   "\<lbrakk> is_up uc; is_up uc' \<rbrakk> \<Longrightarrow> is_up (uc' \<circ> uc)"
   unfolding is_up_def by (simp add: Word.target_size Word.source_size)
 
 lemma of_int_sint_scast:
   "of_int (sint (x :: 'a :: len word)) = (scast x :: 'b :: len word)"
   by (fact Word.of_int_sint) 
 
 lemma scast_of_nat_to_signed [simp]:
   "scast (of_nat x :: 'a :: len word) = (of_nat x :: 'a signed word)"
   by (metis cast_simps(23) scast_scast_id(2))
 
 lemma scast_of_nat_signed_to_unsigned_add:
   "scast (of_nat x + of_nat y :: 'a :: len signed word) = (of_nat x + of_nat y :: 'a :: len word)"
   by (metis of_nat_add scast_of_nat)
 
 lemma scast_of_nat_unsigned_to_signed_add:
   "(scast (of_nat x + of_nat y :: 'a :: len word)) = (of_nat x + of_nat y :: 'a :: len signed word)"
   by (metis Abs_fnat_hom_add scast_of_nat_to_signed)
 
 lemma and_mask_cases:
   fixes x :: "'a :: len word"
   assumes len: "n < LENGTH('a)"
   shows "x && mask n \<in> of_nat ` set [0 ..< 2 ^ n]"
   apply (simp flip: take_bit_eq_mask)
   apply (rule image_eqI [of _ _ \<open>unat (take_bit n x)\<close>])
   using len apply simp_all
   apply transfer
   apply simp
   done
 
 lemma sint_of_nat_ge_zero:
   "x < 2 ^ (LENGTH('a) - 1) \<Longrightarrow> sint (of_nat x :: 'a :: len word) \<ge> 0"
   by (simp add: bit_iff_odd)
 
 lemma sint_eq_uint_2pl:
   "\<lbrakk> (a :: 'a :: len word) < 2 ^ (LENGTH('a) - 1) \<rbrakk>
    \<Longrightarrow> sint a = uint a"
   by (simp add: not_msb_from_less sint_eq_uint word_2p_lem word_size)
 
 lemma sint_of_nat_le:
   "\<lbrakk> b < 2 ^ (LENGTH('a) - 1); a \<le> b \<rbrakk>
    \<Longrightarrow> sint (of_nat a :: 'a :: len word) \<le> sint (of_nat b :: 'a :: len word)"
   by (smt Word_Lemmas.of_nat_power diff_less le_less_trans len_gt_0 len_of_numeral_defs(2)
           nat_power_minus_less of_nat_le_iff sint_eq_uint_2pl uint_nat unat_of_nat_len)
 
 lemma int_eq_sint:
   "x < 2 ^ (LENGTH('a) - 1) \<Longrightarrow> sint (of_nat x :: 'a :: len word) = int x"
   by (smt Word_Lemmas.of_nat_power diff_less le_less_trans len_gt_0 len_of_numeral_defs(2)
           nat_less_le sint_eq_uint_2pl uint_nat unat_lt2p unat_of_nat_len unat_power_lower)
 
 lemma sint_ctz:
   "LENGTH('a) > 2
    \<Longrightarrow> 0 \<le> sint (of_nat (word_ctz (x :: 'a :: len word)) :: 'a signed word)
         \<and> sint (of_nat (word_ctz x) :: 'a signed word) \<le> int (LENGTH('a))"
   apply (subgoal_tac "LENGTH('a) < 2 ^ (LENGTH('a) - 1)")
    apply (rule conjI)
     apply (metis len_signed order_le_less_trans sint_of_nat_ge_zero word_ctz_le)
    apply (metis int_eq_sint len_signed sint_of_nat_le word_ctz_le)
   by (rule small_powers_of_2, simp)
 
 lemma pow_sub_less:
   "\<lbrakk> a + b \<le> LENGTH('a); unat (x :: 'a :: len word) = 2 ^ a \<rbrakk>
    \<Longrightarrow> unat (x * 2 ^ b - 1) < 2 ^ (a + b)"
   by (metis (mono_tags) eq_or_less_helperD not_less of_nat_numeral power_add
                         semiring_1_class.of_nat_power unat_pow_le_intro word_unat.Rep_inverse)
 
 lemma sle_le_2pl:
   "\<lbrakk> (b :: 'a :: len word) < 2 ^ (LENGTH('a) - 1); a \<le> b \<rbrakk> \<Longrightarrow> a <=s b"
   by (simp add: not_msb_from_less word_sle_msb_le)
 
 lemma sless_less_2pl:
   "\<lbrakk> (b :: 'a :: len word) < 2 ^ (LENGTH('a) - 1); a < b \<rbrakk> \<Longrightarrow> a <s b"
   using not_msb_from_less word_sless_msb_less by blast
 
 lemma and_mask2:
   "w << n >> n = w && mask (size w - n)"
   by (cases "n \<le> size w"; clarsimp simp: word_and_le2 and_mask shiftl_zero_size)
 
 lemma unat_of_nat_word_log2:
   "LENGTH('a) < 2 ^ LENGTH('b)
    \<Longrightarrow> unat (of_nat (word_log2 (n :: 'a :: len word)) :: 'b :: len word) = word_log2 n"
   by (metis less_trans unat_of_nat_eq word_log2_max word_size)
 
 lemma aligned_sub_aligned_simple:
   "\<lbrakk> is_aligned a n; is_aligned b n \<rbrakk> \<Longrightarrow> is_aligned (a - b) n"
   by (simp add: aligned_sub_aligned)
 
 lemma minus_one_shift:
   "- (1 << n) = (-1 << n :: 'a::len word)"
   by (simp add: mask_eq_decr_exp NOT_eq flip: mul_not_mask_eq_neg_shiftl)
 
 lemma ucast_eq_mask:
   "(UCAST('a::len \<rightarrow> 'b::len) x = UCAST('a \<rightarrow> 'b) y) =
    (x && mask LENGTH('b) = y && mask LENGTH('b))"
   by (rule iffI; word_eqI_solve)
 
 context
   fixes w :: "'a::len word"
 begin
 
 private lemma sbintrunc_uint_ucast:
   assumes "Suc n = LENGTH('b::len)"
   shows "sbintrunc n (uint (ucast w :: 'b word)) = sbintrunc n (uint w)"
   by (metis assms sbintrunc_bintrunc ucast_eq word_ubin.eq_norm)
 
 private lemma test_bit_sbintrunc:
   assumes "i < LENGTH('a)"
   shows "(word_of_int (sbintrunc n (uint w)) :: 'a word) !! i
            = (if n < i then w !! n else w !! i)"
   using assms by (simp add: nth_sbintr)
                  (simp add: test_bit_bin)
 
 private lemma test_bit_sbintrunc_ucast:
   assumes len_a: "i < LENGTH('a)"
   shows "(word_of_int (sbintrunc (LENGTH('b) - 1) (uint (ucast w :: 'b word))) :: 'a word) !! i
           = (if LENGTH('b::len) \<le> i then w !! (LENGTH('b) - 1) else w !! i)"
   apply (subst sbintrunc_uint_ucast)
    apply simp
   apply (subst test_bit_sbintrunc)
    apply (rule len_a)
   apply (rule if_cong[OF _ refl refl])
   using leD less_linear by fastforce
 
 lemma scast_ucast_high_bits:
   \<open>scast (ucast w :: 'b::len word) = w
      \<longleftrightarrow> (\<forall> i \<in> {LENGTH('b) ..< size w}. w !! i = w !! (LENGTH('b) - 1))\<close>
 proof (cases \<open>LENGTH('a) \<le> LENGTH('b)\<close>)
   case True
   moreover define m where \<open>m = LENGTH('b) - LENGTH('a)\<close>
   ultimately have \<open>LENGTH('b) = m + LENGTH('a)\<close>
     by simp
   then show ?thesis
     apply (simp_all add: signed_ucast_eq word_size)
     apply (rule bit_word_eqI)
     apply (simp add: bit_signed_take_bit_iff)
     done
 next
   case False
   define q where \<open>q = LENGTH('b) - 1\<close>
   then have \<open>LENGTH('b) = Suc q\<close>
     by simp
   moreover define m where \<open>m = Suc LENGTH('a) - LENGTH('b)\<close>
   with False \<open>LENGTH('b) = Suc q\<close> have \<open>LENGTH('a) = m + q\<close>
     by (simp add: not_le)
   ultimately show ?thesis
     apply (simp_all add: signed_ucast_eq word_size)
     apply (transfer fixing: m q)
     apply (simp add: signed_take_bit_take_bit)
     apply rule
     apply (subst bit_eq_iff)
     apply (simp add: bit_take_bit_iff bit_signed_take_bit_iff min_def)
     apply (auto simp add: Suc_le_eq)
     using less_imp_le_nat apply blast
     using less_imp_le_nat apply blast
     done
 qed
   
 lemma scast_ucast_mask_compare:
   "scast (ucast w :: 'b::len word) = w
    \<longleftrightarrow> (w \<le> mask (LENGTH('b) - 1) \<or> ~~(mask (LENGTH('b) - 1)) \<le> w)"
   apply (clarsimp simp: le_mask_high_bits neg_mask_le_high_bits scast_ucast_high_bits word_size)
   apply (rule iffI; clarsimp)
    apply (rename_tac i j; case_tac "i = LENGTH('b) - 1"; case_tac "j = LENGTH('b) - 1")
   by auto
 
 lemma ucast_less_shiftl_helper':
   "\<lbrakk> LENGTH('b) + (a::nat) < LENGTH('a); 2 ^ (LENGTH('b) + a) \<le> n\<rbrakk>
    \<Longrightarrow> (ucast (x :: 'b::len word) << a) < (n :: 'a::len word)"
   apply (erule order_less_le_trans[rotated])
   using ucast_less[where x=x and 'a='a]
   apply (simp only: shiftl_t2n field_simps)
   apply (rule word_less_power_trans2; simp)
   done
 
 end
 
 lemma ucast_ucast_mask2:
   "is_down (UCAST ('a \<rightarrow> 'b)) \<Longrightarrow>
    UCAST ('b::len \<rightarrow> 'c::len) (UCAST ('a::len \<rightarrow> 'b::len) x) = UCAST ('a \<rightarrow> 'c) (x && mask LENGTH('b))"
   by word_eqI_solve
 
 lemma ucast_NOT:
   "ucast (~~x) = ~~(ucast x) && mask (LENGTH('a))" for x::"'a::len word"
   by word_eqI
 
 lemma ucast_NOT_down:
   "is_down UCAST('a::len \<rightarrow> 'b::len) \<Longrightarrow> UCAST('a \<rightarrow> 'b) (~~x) = ~~(UCAST('a \<rightarrow> 'b) x)"
   by word_eqI
 
 lemma of_bl_mult_and_not_mask_eq:
   "\<lbrakk>is_aligned (a :: 'a::len word) n; length b + m \<le> n\<rbrakk>
    \<Longrightarrow> a + of_bl b * (2^m) && ~~(mask n) = a"
   by (smt add.left_neutral add_diff_cancel_right' add_mask_lower_bits and_mask_plus is_aligned_mask
           is_aligned_weaken le_less_trans of_bl_length2 subtract_mask(1))
 
 lemma bin_to_bl_of_bl_eq:
   "\<lbrakk>is_aligned (a::'a::len word) n; length b + c \<le> n; length b + c < LENGTH('a)\<rbrakk>
   \<Longrightarrow> bin_to_bl (length b) (uint ((a + of_bl b * 2^c) >> c)) = b"
   apply (subst word_plus_and_or_coroll)
    apply (erule is_aligned_get_word_bits)
     apply (rule is_aligned_AND_less_0)
      apply (simp add: is_aligned_mask)
     apply (rule order_less_le_trans)
      apply (rule of_bl_length2)
      apply simp
     apply (simp add: two_power_increasing)
    apply simp
   apply (rule nth_equalityI)
    apply (simp only: len_bin_to_bl)
   apply (clarsimp simp only: len_bin_to_bl nth_bin_to_bl word_test_bit_def[symmetric])
   apply (simp add: nth_shiftr nth_shiftl
                    shiftl_t2n[where n=c, simplified mult.commute, simplified, symmetric])
   apply (simp add: is_aligned_nth[THEN iffD1, rule_format] test_bit_of_bl rev_nth)
   apply arith
   done
 
 end
diff --git a/thys/Word_Lib/Word_Lemmas_32.thy b/thys/Word_Lib/Word_Lemmas_32.thy
--- a/thys/Word_Lib/Word_Lemmas_32.thy
+++ b/thys/Word_Lib/Word_Lemmas_32.thy
@@ -1,305 +1,305 @@
 (*
  * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
  *
  * SPDX-License-Identifier: BSD-2-Clause
  *)
 
 section "Lemmas for Word Length 32"
 
 theory Word_Lemmas_32
 imports
   Word_Lemmas
   Word_Setup_32
 begin
 
 lemma ucast_8_32_inj:
   "inj (ucast ::  8 word \<Rightarrow> 32 word)"
   by (rule down_ucast_inj) (clarsimp simp: is_down_def target_size source_size)
 
 lemma upto_2_helper:
   "{0..<2 :: 32 word} = {0, 1}"
   by (safe; simp) unat_arith
 
 lemmas upper_bits_unset_is_l2p_32 = upper_bits_unset_is_l2p [where 'a=32, folded word_bits_def]
 lemmas le_2p_upper_bits_32 = le_2p_upper_bits [where 'a=32, folded word_bits_def]
 lemmas le2p_bits_unset_32 = le2p_bits_unset[where 'a=32, folded word_bits_def]
 
 lemma word_bits_len_of:
   "len_of TYPE (32) = word_bits"
   by (simp add: word_bits_conv)
 
 lemmas unat_power_lower32' = unat_power_lower[where 'a=32]
 lemmas unat_power_lower32 [simp] = unat_power_lower32'[unfolded word_bits_len_of]
 
 lemmas word32_less_sub_le' = word_less_sub_le[where 'a = 32]
 lemmas word32_less_sub_le[simp] = word32_less_sub_le' [folded word_bits_def]
 
 lemma word_bits_size:
   "size (w::word32) = word_bits"
   by (simp add: word_bits_def word_size)
 
 lemmas word32_power_less_1' = word_power_less_1[where 'a = 32]
 lemmas word32_power_less_1[simp] = word32_power_less_1'[folded word_bits_def]
 
 lemma of_nat32_0:
   "\<lbrakk>of_nat n = (0::word32); n < 2 ^ word_bits\<rbrakk> \<Longrightarrow> n = 0"
   by (erule of_nat_0, simp add: word_bits_def)
 
 lemma unat_mask_2_less_4:
   "unat (p && mask 2 :: word32) < 4"
   apply (rule unat_less_helper)
   apply (rule order_le_less_trans, rule word_and_le1)
   apply (simp add: mask_eq)
   done
 
 lemmas unat_of_nat32' = unat_of_nat_eq[where 'a=32]
 lemmas unat_of_nat32 = unat_of_nat32'[unfolded word_bits_len_of]
 
 lemmas word_power_nonzero_32 = word_power_nonzero [where 'a=32, folded word_bits_def]
 
 lemmas unat_mult_simple = iffD1 [OF unat_mult_lem [where 'a = 32, unfolded word_bits_len_of]]
 
 lemmas div_power_helper_32 = div_power_helper [where 'a=32, folded word_bits_def]
 
 lemma n_less_word_bits:
   "(n < word_bits) = (n < 32)"
   by (simp add: word_bits_def)
 
 lemmas of_nat_less_pow_32 = of_nat_power [where 'a=32, folded word_bits_def]
 
 lemma lt_word_bits_lt_pow:
   "sz < word_bits \<Longrightarrow> sz < 2 ^ word_bits"
   by (simp add: word_bits_conv)
 
 lemma unat_less_word_bits:
   fixes y :: word32
   shows "x < unat y \<Longrightarrow> x < 2 ^ word_bits"
   unfolding word_bits_def
   by (rule order_less_trans [OF _ unat_lt2p])
 
 lemmas unat_mask_word32' = unat_mask[where 'a=32]
 lemmas unat_mask_word32 = unat_mask_word32'[folded word_bits_def]
 
 lemma unat_less_2p_word_bits:
   "unat (x :: 32 word) < 2 ^ word_bits"
   apply (simp only: word_bits_def)
   apply (rule unat_lt2p)
   done
 
 lemma Suc_unat_mask_div:
   "Suc (unat (mask sz div word_size::word32)) = 2 ^ (min sz word_bits - 2)"
   apply (case_tac "sz < word_bits")
-   apply (case_tac "2\<le>sz")
+   apply (case_tac "2 \<le> sz")
     apply (clarsimp simp: word_size_def word_bits_def min_def mask_eq)
     apply (drule (2) Suc_div_unat_helper
            [where 'a=32 and sz=sz and us=2, simplified, symmetric])
    apply (simp add: not_le word_size_def word_bits_def)
    apply (case_tac sz, simp add: unat_word_ariths)
    apply (case_tac nat, simp add: unat_word_ariths
                                   unat_mask_word32 min_def word_bits_def)
    apply simp
   apply (simp add: unat_word_ariths
                    unat_mask_word32 min_def word_bits_def word_size_def)
   done
 
 lemmas word32_minus_one_le' = word_minus_one_le[where 'a=32]
 lemmas word32_minus_one_le = word32_minus_one_le'[simplified]
 
 lemma ucast_not_helper:
   fixes a::word8
   assumes a: "a \<noteq> 0xFF"
   shows "ucast a \<noteq> (0xFF::word32)"
 proof
   assume "ucast a = (0xFF::word32)"
   also
   have "(0xFF::word32) = ucast (0xFF::word8)" by simp
   finally
   show False using a
     apply -
     apply (drule up_ucast_inj, simp)
     apply simp
     done
 qed
 
 lemma less_4_cases:
   "(x::word32) < 4 \<Longrightarrow> x=0 \<or> x=1 \<or> x=2 \<or> x=3"
   apply clarsimp
   apply (drule word_less_cases, erule disjE, simp, simp)+
   done
 
 lemma unat_ucast_8_32:
   fixes x :: "word8"
   shows "unat (ucast x :: word32) = unat x"
   by transfer simp
 
 lemma if_then_1_else_0:
   "((if P then 1 else 0) = (0 :: word32)) = (\<not> P)"
   by simp
 
 lemma if_then_0_else_1:
   "((if P then 0 else 1) = (0 :: word32)) = (P)"
   by simp
 
 lemmas if_then_simps = if_then_0_else_1 if_then_1_else_0
 
 lemma ucast_le_ucast_8_32:
   "(ucast x \<le> (ucast y :: word32)) = (x \<le> (y :: word8))"
   by (simp add: ucast_le_ucast)
 
 lemma in_16_range:
   "0 \<in> S \<Longrightarrow> r \<in> (\<lambda>x. r + x * (16 :: word32)) ` S"
   "n - 1 \<in> S \<Longrightarrow> (r + (16 * n - 16)) \<in> (\<lambda>x :: word32. r + x * 16) ` S"
   by (clarsimp simp: image_def elim!: bexI[rotated])+
 
 lemma eq_2_32_0:
   "(2 ^ 32 :: word32) = 0"
   by simp
 
 lemma x_less_2_0_1:
   fixes x :: word32 shows
   "x < 2 \<Longrightarrow> x = 0 \<or> x = 1"
   by (rule x_less_2_0_1') auto
 
 lemmas mask_32_max_word  = max_word_mask [symmetric, where 'a=32, simplified]
 
 lemma of_nat32_n_less_equal_power_2:
  "n < 32 \<Longrightarrow> ((of_nat n)::32 word) < 2 ^ n"
   by (rule of_nat_n_less_equal_power_2, clarsimp simp: word_size)
 
 lemma word_rsplit_0:
   "word_rsplit (0 :: word32) = [0, 0, 0, 0 :: word8]"
   by (simp add: word_rsplit_def bin_rsplit_def)
 
 lemma unat_ucast_10_32 :
   fixes x :: "10 word"
   shows "unat (ucast x :: word32) = unat x"
   by transfer simp
 
 lemma bool_mask [simp]:
   fixes x :: word32
   shows "(0 < x && 1) = (x && 1 = 1)"
   by (rule bool_mask') auto
 
 lemma word32_bounds:
   "- (2 ^ (size (x :: word32) - 1)) = (-2147483648 :: int)"
   "((2 ^ (size (x :: word32) - 1)) - 1) = (2147483647 :: int)"
   "- (2 ^ (size (y :: 32 signed word) - 1)) = (-2147483648 :: int)"
   "((2 ^ (size (y :: 32 signed word) - 1)) - 1) = (2147483647 :: int)"
   by (simp_all add: word_size)
 
 lemma word_ge_min:"sint (x::32 word) \<ge> -2147483648"
   by (metis sint_ge word32_bounds(1) word_size)
 
 lemmas signed_arith_ineq_checks_to_eq_word32'
     = signed_arith_ineq_checks_to_eq[where 'a=32]
       signed_arith_ineq_checks_to_eq[where 'a="32 signed"]
 
 lemmas signed_arith_ineq_checks_to_eq_word32
     = signed_arith_ineq_checks_to_eq_word32' [unfolded word32_bounds]
 
 lemmas signed_mult_eq_checks32_to_64'
     = signed_mult_eq_checks_double_size[where 'a=32 and 'b=64]
       signed_mult_eq_checks_double_size[where 'a="32 signed" and 'b=64]
 
 lemmas signed_mult_eq_checks32_to_64 = signed_mult_eq_checks32_to_64'[simplified]
 
 lemmas sdiv_word32_max' = sdiv_word_max [where 'a=32] sdiv_word_max [where 'a="32 signed"]
 lemmas sdiv_word32_max = sdiv_word32_max'[simplified word_size, simplified]
 
 lemmas sdiv_word32_min' = sdiv_word_min [where 'a=32] sdiv_word_min [where 'a="32 signed"]
 lemmas sdiv_word32_min = sdiv_word32_min' [simplified word_size, simplified]
 
 lemmas sint32_of_int_eq' = sint_of_int_eq [where 'a=32]
 lemmas sint32_of_int_eq = sint32_of_int_eq' [simplified]
 
 lemma ucast_of_nats [simp]:
   "(ucast (of_nat x :: word32) :: sword32) = (of_nat x)"
   "(ucast (of_nat x :: word32) :: sword16) = (of_nat x)"
   "(ucast (of_nat x :: word32) :: sword8) = (of_nat x)"
   "(ucast (of_nat x :: word16) :: sword16) = (of_nat x)"
   "(ucast (of_nat x :: word16) :: sword8) = (of_nat x)"
   "(ucast (of_nat x :: word8) :: sword8) = (of_nat x)"
   by (simp_all add: of_nat_take_bit take_bit_word_eq_self)
 
 lemmas signed_shift_guard_simpler_32'
     = power_strict_increasing_iff[where b="2 :: nat" and y=31]
 lemmas signed_shift_guard_simpler_32 = signed_shift_guard_simpler_32'[simplified]
 
 lemma word32_31_less:
   "31 < len_of TYPE (32 signed)" "31 > (0 :: nat)"
   "31 < len_of TYPE (32)" "31 > (0 :: nat)"
   by auto
 
 lemmas signed_shift_guard_to_word_32
     = signed_shift_guard_to_word[OF word32_31_less(1-2)]
     signed_shift_guard_to_word[OF word32_31_less(3-4)]
 
 lemma le_step_down_word_3:
   fixes x :: "32 word"
   shows "\<lbrakk>x \<le>  y; x \<noteq> y; y < 2 ^ 32 - 1\<rbrakk> \<Longrightarrow> x \<le> y - 1"
   by (rule le_step_down_word_2, assumption+)
 
 lemma shiftr_1:
   "(x::word32) >> 1 = 0 \<Longrightarrow> x < 2"
   by word_bitwise clarsimp
 
 lemma has_zero_byte:
   "~~ (((((v::word32) && 0x7f7f7f7f) + 0x7f7f7f7f) || v) || 0x7f7f7f7f) \<noteq> 0
     \<Longrightarrow> v && 0xff000000 = 0 \<or> v && 0xff0000 = 0 \<or> v && 0xff00 = 0 \<or> v && 0xff = 0"
   apply clarsimp
   apply word_bitwise
   by metis
 
 lemma mask_step_down_32:
   \<open>\<exists>x. mask x = b\<close> if \<open>b && 1 = 1\<close>
     and \<open>\<exists>x. x < 32 \<and> mask x = b >> 1\<close> for b :: \<open>32word\<close>
 proof -
   from \<open>b && 1 = 1\<close> have \<open>odd b\<close>
     by (auto simp add: mod_2_eq_odd and_one_eq)
   then have \<open>b mod 2 = 1\<close>
     using odd_iff_mod_2_eq_one by blast
   from \<open>\<exists>x. x < 32 \<and> mask x = b >> 1\<close> obtain x where \<open>x < 32\<close> \<open>mask x = b >> 1\<close> by blast
   then have \<open>mask x = b div 2\<close>
     using shiftr1_is_div_2 [of b] by simp
   with \<open>b mod 2 = 1\<close> have \<open>2 * mask x + 1 = 2 * (b div 2) + b mod 2\<close>
     by (simp only:) 
   also have \<open>\<dots> = b\<close>
     by (simp add: mult_div_mod_eq)
   finally have \<open>2 * mask x + 1 = b\<close> .
   moreover have \<open>mask (Suc x) = 2 * mask x + (1 :: 'a::len word)\<close>
     by (simp add: mask_Suc_rec)
   ultimately show ?thesis
     by auto
 qed
 
 lemma unat_of_int_32:
   "\<lbrakk>i \<ge> 0; i \<le>2 ^ 31\<rbrakk> \<Longrightarrow> (unat ((of_int i)::sword32)) = nat i"
   unfolding unat_eq_nat_uint
   apply (subst eq_nat_nat_iff)
     apply (auto simp add: take_bit_int_eq_self)
   done
 
 lemmas word_ctz_not_minus_1_32 = word_ctz_not_minus_1[where 'a=32, simplified]
 
 (* Helper for packing then unpacking a 64-bit variable. *)
 lemma cast_chunk_assemble_id_64[simp]:
   "(((ucast ((ucast (x::64 word))::32 word))::64 word) || (((ucast ((ucast (x >> 32))::32 word))::64 word) << 32)) = x"
   by (simp add:cast_chunk_assemble_id)
 
 (* Another variant of packing and unpacking a 64-bit variable. *)
 lemma cast_chunk_assemble_id_64'[simp]:
   "(((ucast ((scast (x::64 word))::32 word))::64 word) || (((ucast ((scast (x >> 32))::32 word))::64 word) << 32)) = x"
   by (simp add:cast_chunk_scast_assemble_id)
 
 (* Specialisations of down_cast_same for adding to local simpsets. *)
 lemma cast_down_u64: "(scast::64 word \<Rightarrow> 32 word) = (ucast::64 word \<Rightarrow> 32 word)"
   apply (subst down_cast_same[symmetric])
    apply (simp add:is_down)+
   done
 
 lemma cast_down_s64: "(scast::64 sword \<Rightarrow> 32 word) = (ucast::64 sword \<Rightarrow> 32 word)"
   apply (subst down_cast_same[symmetric])
    apply (simp add:is_down)+
   done
 
 end
diff --git a/thys/Word_Lib/Word_Lemmas_64.thy b/thys/Word_Lib/Word_Lemmas_64.thy
--- a/thys/Word_Lib/Word_Lemmas_64.thy
+++ b/thys/Word_Lib/Word_Lemmas_64.thy
@@ -1,294 +1,294 @@
 (*
  * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
  *
  * SPDX-License-Identifier: BSD-2-Clause
  *)
 
 section "Lemmas for Word Length 64"
 
 theory Word_Lemmas_64
 imports
   Word_Lemmas
   Word_Setup_64
 begin
 
 lemma ucast_8_64_inj:
   "inj (ucast ::  8 word \<Rightarrow> 64 word)"
   by (rule down_ucast_inj) (clarsimp simp: is_down_def target_size source_size)
 
 lemma upto_2_helper:
   "{0..<2 :: 64 word} = {0, 1}"
   by (safe; simp) unat_arith
 
 lemmas upper_bits_unset_is_l2p_64 = upper_bits_unset_is_l2p [where 'a=64, folded word_bits_def]
 lemmas le_2p_upper_bits_64 = le_2p_upper_bits [where 'a=64, folded word_bits_def]
 lemmas le2p_bits_unset_64 = le2p_bits_unset[where 'a=64, folded word_bits_def]
 
 lemma word_bits_len_of:
   "len_of TYPE (64) = word_bits"
   by (simp add: word_bits_conv)
 
 lemmas unat_power_lower64' = unat_power_lower[where 'a=64]
 lemmas unat_power_lower64 [simp] = unat_power_lower64'[unfolded word_bits_len_of]
 
 lemmas word64_less_sub_le' = word_less_sub_le[where 'a = 64]
 lemmas word64_less_sub_le[simp] = word64_less_sub_le' [folded word_bits_def]
 
 lemma word_bits_size:
   "size (w::word64) = word_bits"
   by (simp add: word_bits_def word_size)
 
 lemmas word64_power_less_1' = word_power_less_1[where 'a = 64]
 lemmas word64_power_less_1[simp] = word64_power_less_1'[folded word_bits_def]
 
 lemma of_nat64_0:
   "\<lbrakk>of_nat n = (0::word64); n < 2 ^ word_bits\<rbrakk> \<Longrightarrow> n = 0"
   by (erule of_nat_0, simp add: word_bits_def)
 
 lemma unat_mask_2_less_4:
   "unat (p && mask 2 :: word64) < 4"
   apply (rule unat_less_helper)
   apply (rule order_le_less_trans, rule word_and_le1)
   apply (simp add: mask_eq)
   done
 
 lemmas unat_of_nat64' = unat_of_nat_eq[where 'a=64]
 lemmas unat_of_nat64 = unat_of_nat64'[unfolded word_bits_len_of]
 
 lemmas word_power_nonzero_64 = word_power_nonzero [where 'a=64, folded word_bits_def]
 
 lemmas unat_mult_simple = iffD1 [OF unat_mult_lem [where 'a = 64, unfolded word_bits_len_of]]
 
 lemmas div_power_helper_64 = div_power_helper [where 'a=64, folded word_bits_def]
 
 lemma n_less_word_bits:
   "(n < word_bits) = (n < 64)"
   by (simp add: word_bits_def)
 
 lemmas of_nat_less_pow_64 = of_nat_power [where 'a=64, folded word_bits_def]
 
 lemma lt_word_bits_lt_pow:
   "sz < word_bits \<Longrightarrow> sz < 2 ^ word_bits"
   by (simp add: word_bits_conv)
 
 lemma unat_less_word_bits:
   fixes y :: word64
   shows "x < unat y \<Longrightarrow> x < 2 ^ word_bits"
   unfolding word_bits_def
   by (rule order_less_trans [OF _ unat_lt2p])
 
 lemmas unat_mask_word64' = unat_mask[where 'a=64]
 lemmas unat_mask_word64 = unat_mask_word64'[folded word_bits_def]
 
 lemma unat_less_2p_word_bits:
   "unat (x :: 64 word) < 2 ^ word_bits"
   apply (simp only: word_bits_def)
   apply (rule unat_lt2p)
   done
 
 lemma Suc_unat_mask_div:
   "Suc (unat (mask sz div word_size::word64)) = 2 ^ (min sz word_bits - 3)"
   apply (case_tac "sz < word_bits")
-   apply (case_tac "3\<le>sz")
+   apply (case_tac "3 \<le> sz")
     apply (clarsimp simp: word_size_def word_bits_def min_def mask_eq)
     apply (drule (2) Suc_div_unat_helper
            [where 'a=64 and sz=sz and us=3, simplified, symmetric])
    apply (simp add: not_le word_size_def word_bits_def)
    apply (case_tac sz, simp add: unat_word_ariths)
    apply (case_tac nat, simp add: unat_word_ariths
                                   unat_mask_word64 min_def word_bits_def)
    apply (case_tac nata, simp add: unat_word_ariths unat_mask_word64 word_bits_def)
    apply simp
   apply (simp add: unat_word_ariths
                    unat_mask_word64 min_def word_bits_def word_size_def)
   done
 
 lemmas word64_minus_one_le' = word_minus_one_le[where 'a=64]
 lemmas word64_minus_one_le = word64_minus_one_le'[simplified]
 
 lemma ucast_not_helper:
   fixes a::word8
   assumes a: "a \<noteq> 0xFF"
   shows "ucast a \<noteq> (0xFF::word64)"
 proof
   assume "ucast a = (0xFF::word64)"
   also
   have "(0xFF::word64) = ucast (0xFF::word8)" by simp
   finally
   show False using a
     apply -
     apply (drule up_ucast_inj, simp)
     apply simp
     done
 qed
 
 lemma less_4_cases:
   "(x::word64) < 4 \<Longrightarrow> x=0 \<or> x=1 \<or> x=2 \<or> x=3"
   apply clarsimp
   apply (drule word_less_cases, erule disjE, simp, simp)+
   done
 
 lemma if_then_1_else_0:
   "((if P then 1 else 0) = (0 :: word64)) = (\<not> P)"
   by simp
 
 lemma if_then_0_else_1:
   "((if P then 0 else 1) = (0 :: word64)) = (P)"
   by simp
 
 lemmas if_then_simps = if_then_0_else_1 if_then_1_else_0
 
 lemma ucast_le_ucast_8_64:
   "(ucast x \<le> (ucast y :: word64)) = (x \<le> (y :: word8))"
   by (simp add: ucast_le_ucast)
 
 lemma in_16_range:
   "0 \<in> S \<Longrightarrow> r \<in> (\<lambda>x. r + x * (16 :: word64)) ` S"
   "n - 1 \<in> S \<Longrightarrow> (r + (16 * n - 16)) \<in> (\<lambda>x :: word64. r + x * 16) ` S"
   by (clarsimp simp: image_def elim!: bexI[rotated])+
 
 lemma eq_2_64_0:
   "(2 ^ 64 :: word64) = 0"
   by simp
 
 lemma x_less_2_0_1:
   fixes x :: word64 shows
   "x < 2 \<Longrightarrow> x = 0 \<or> x = 1"
   by (rule x_less_2_0_1') auto
 
 lemmas mask_64_max_word  = max_word_mask [symmetric, where 'a=64, simplified]
 
 lemma of_nat64_n_less_equal_power_2:
  "n < 64 \<Longrightarrow> ((of_nat n)::64 word) < 2 ^ n"
   by (rule of_nat_n_less_equal_power_2, clarsimp simp: word_size)
 
 lemma word_rsplit_0:
   "word_rsplit (0 :: word64) = [0, 0, 0, 0, 0, 0, 0, 0 :: word8]"
   by (simp add: word_rsplit_def bin_rsplit_def)
 
 lemma unat_ucast_10_64 :
   fixes x :: "10 word"
   shows "unat (ucast x :: word64) = unat x"
   by transfer simp
 
 lemma bool_mask [simp]:
   fixes x :: word64
   shows "(0 < x && 1) = (x && 1 = 1)"
   by (rule bool_mask') auto
 
 lemma word64_bounds:
   "- (2 ^ (size (x :: word64) - 1)) = (-9223372036854775808 :: int)"
   "((2 ^ (size (x :: word64) - 1)) - 1) = (9223372036854775807 :: int)"
   "- (2 ^ (size (y :: 64 signed word) - 1)) = (-9223372036854775808 :: int)"
   "((2 ^ (size (y :: 64 signed word) - 1)) - 1) = (9223372036854775807 :: int)"
   by (simp_all add: word_size)
 
 lemma word_ge_min:"sint (x::64 word) \<ge> -9223372036854775808"
   by (metis sint_ge word64_bounds(1) word_size)
 
 lemmas signed_arith_ineq_checks_to_eq_word64'
     = signed_arith_ineq_checks_to_eq[where 'a=64]
       signed_arith_ineq_checks_to_eq[where 'a="64 signed"]
 
 lemmas signed_arith_ineq_checks_to_eq_word64
     = signed_arith_ineq_checks_to_eq_word64' [unfolded word64_bounds]
 
 lemmas signed_mult_eq_checks64_to_64'
     = signed_mult_eq_checks_double_size[where 'a=64 and 'b=64]
       signed_mult_eq_checks_double_size[where 'a="64 signed" and 'b=64]
 
 lemmas signed_mult_eq_checks64_to_64 = signed_mult_eq_checks64_to_64'[simplified]
 
 lemmas sdiv_word64_max' = sdiv_word_max [where 'a=64] sdiv_word_max [where 'a="64 signed"]
 lemmas sdiv_word64_max = sdiv_word64_max'[simplified word_size, simplified]
 
 lemmas sdiv_word64_min' = sdiv_word_min [where 'a=64] sdiv_word_min [where 'a="64 signed"]
 lemmas sdiv_word64_min = sdiv_word64_min' [simplified word_size, simplified]
 
 lemmas sint64_of_int_eq' = sint_of_int_eq [where 'a=64]
 lemmas sint64_of_int_eq = sint64_of_int_eq' [simplified]
 
 lemma ucast_of_nats [simp]:
   "(ucast (of_nat x :: word64) :: sword64) = (of_nat x)"
   "(ucast (of_nat x :: word64) :: sword16) = (of_nat x)"
   "(ucast (of_nat x :: word64) :: sword8) = (of_nat x)"
   "(ucast (of_nat x :: word16) :: sword16) = (of_nat x)"
   "(ucast (of_nat x :: word16) :: sword8) = (of_nat x)"
   "(ucast (of_nat x :: word8) :: sword8) = (of_nat x)"
   by (simp_all add: of_nat_take_bit take_bit_word_eq_self)
 
 lemmas signed_shift_guard_simpler_64'
     = power_strict_increasing_iff[where b="2 :: nat" and y=31]
 lemmas signed_shift_guard_simpler_64 = signed_shift_guard_simpler_64'[simplified]
 
 lemma word64_31_less:
   "31 < len_of TYPE (64 signed)" "31 > (0 :: nat)"
   "31 < len_of TYPE (64)" "31 > (0 :: nat)"
   by auto
 
 lemmas signed_shift_guard_to_word_64
     = signed_shift_guard_to_word[OF word64_31_less(1-2)]
     signed_shift_guard_to_word[OF word64_31_less(3-4)]
 
 lemma le_step_down_word_3:
   fixes x :: "64 word"
   shows "\<lbrakk>x \<le>  y; x \<noteq> y; y < 2 ^ 64 - 1\<rbrakk> \<Longrightarrow> x \<le> y - 1"
   by (rule le_step_down_word_2, assumption+)
 
 lemma shiftr_1:
   "(x::word64) >> 1 = 0 \<Longrightarrow> x < 2"
   by word_bitwise clarsimp
 
 lemma mask_step_down_64:
   \<open>\<exists>x. mask x = b\<close> if \<open>b && 1 = 1\<close>
     and \<open>\<exists>x. x < 64 \<and> mask x = b >> 1\<close> for b :: \<open>64word\<close>
 proof -
   from \<open>b && 1 = 1\<close> have \<open>odd b\<close>
     by (auto simp add: mod_2_eq_odd and_one_eq)
   then have \<open>b mod 2 = 1\<close>
     using odd_iff_mod_2_eq_one by blast
   from \<open>\<exists>x. x < 64 \<and> mask x = b >> 1\<close> obtain x where \<open>x < 64\<close> \<open>mask x = b >> 1\<close> by blast
   then have \<open>mask x = b div 2\<close>
     using shiftr1_is_div_2 [of b] by simp
   with \<open>b mod 2 = 1\<close> have \<open>2 * mask x + 1 = 2 * (b div 2) + b mod 2\<close>
     by (simp only:) 
   also have \<open>\<dots> = b\<close>
     by (simp add: mult_div_mod_eq)
   finally have \<open>2 * mask x + 1 = b\<close> .
   moreover have \<open>mask (Suc x) = 2 * mask x + (1 :: 'a::len word)\<close>
     by (simp add: mask_Suc_rec)
   ultimately show ?thesis
     by auto
 qed
 
 lemma unat_of_int_64:
   "\<lbrakk>i \<ge> 0; i \<le> 2 ^ 63\<rbrakk> \<Longrightarrow> (unat ((of_int i)::sword64)) = nat i"
   unfolding unat_eq_nat_uint
   apply (subst eq_nat_nat_iff)
   apply (simp_all add: take_bit_int_eq_self)
   done
 
 lemmas word_ctz_not_minus_1_64 = word_ctz_not_minus_1[where 'a=64, simplified]
 
 (* Helper for packing then unpacking a 64-bit variable. *)
 lemma cast_chunk_assemble_id_64[simp]:
   "(((ucast ((ucast (x::64 word))::32 word))::64 word) || (((ucast ((ucast (x >> 32))::32 word))::64 word) << 32)) = x"
   by (simp add:cast_chunk_assemble_id)
 
 (* Another variant of packing and unpacking a 64-bit variable. *)
 lemma cast_chunk_assemble_id_64'[simp]:
   "(((ucast ((scast (x::64 word))::32 word))::64 word) || (((ucast ((scast (x >> 32))::32 word))::64 word) << 32)) = x"
   by (simp add:cast_chunk_scast_assemble_id)
 
 (* Specialisations of down_cast_same for adding to local simpsets. *)
 lemma cast_down_u64: "(scast::64 word \<Rightarrow> 32 word) = (ucast::64 word \<Rightarrow> 32 word)"
   apply (subst down_cast_same[symmetric])
    apply (simp add:is_down)+
   done
 
 lemma cast_down_s64: "(scast::64 sword \<Rightarrow> 32 word) = (ucast::64 sword \<Rightarrow> 32 word)"
   apply (subst down_cast_same[symmetric])
    apply (simp add:is_down)+
   done
 
 end
diff --git a/thys/Word_Lib/Word_Lib.thy b/thys/Word_Lib/Word_Lib.thy
--- a/thys/Word_Lib/Word_Lib.thy
+++ b/thys/Word_Lib/Word_Lib.thy
@@ -1,744 +1,744 @@
 (*
  * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
  *
  * SPDX-License-Identifier: BSD-2-Clause
  *)
 
 section "Additional Word Operations"
 
 theory Word_Lib
   imports
   "HOL-Library.Signed_Division"
   "HOL-Word.Misc_set_bit"
   Word_Syntax
   Signed_Words
 begin
 
 definition
   ptr_add :: "'a :: len word \<Rightarrow> nat \<Rightarrow> 'a word" where
   "ptr_add ptr n \<equiv> ptr + of_nat n"
 
 definition
   complement :: "'a :: len word \<Rightarrow> 'a word"  where
  "complement x \<equiv> ~~ x"
 
 definition
   alignUp :: "'a::len word \<Rightarrow> nat \<Rightarrow> 'a word" where
  "alignUp x n \<equiv> x + 2 ^ n - 1 && complement (2 ^ n - 1)"
 
 (* standard notation for blocks of 2^n-1 words, usually aligned;
    abbreviation so it simplifies directly *)
 abbreviation mask_range :: "'a::len word \<Rightarrow> nat \<Rightarrow> 'a word set" where
   "mask_range p n \<equiv> {p .. p + mask n}"
 
 (* Haskellish names/syntax *)
 notation (input)
   test_bit ("testBit")
 
 definition
   w2byte :: "'a :: len word \<Rightarrow> 8 word" where
   "w2byte \<equiv> ucast"
 
 lemmas sdiv_int_def = signed_divide_int_def
 lemmas smod_int_def = signed_modulo_int_def
 
 instantiation word :: (len) signed_division
 begin
 
 lift_definition signed_divide_word :: \<open>'a::len word \<Rightarrow> 'a word \<Rightarrow> 'a word\<close>
   is \<open>\<lambda>k l. signed_take_bit (LENGTH('a) - Suc 0) k sdiv signed_take_bit (LENGTH('a) - Suc 0) l\<close>
   by (simp flip: signed_take_bit_decr_length_iff)
 
 lift_definition signed_modulo_word :: \<open>'a::len word \<Rightarrow> 'a word \<Rightarrow> 'a word\<close>
   is \<open>\<lambda>k l. signed_take_bit (LENGTH('a) - Suc 0) k smod signed_take_bit (LENGTH('a) - Suc 0) l\<close>
   by (simp flip: signed_take_bit_decr_length_iff)
 
 instance ..
 
 end
 
-lemma sdiv_word_def:
+lemma sdiv_word_def [code]:
   \<open>v sdiv w = word_of_int (sint v sdiv sint w)\<close>
   for v w :: \<open>'a::len word\<close>
   by transfer simp
 
-lemma smod_word_def:
+lemma smod_word_def [code]:
   \<open>v smod w = word_of_int (sint v smod sint w)\<close>
   for v w :: \<open>'a::len word\<close>
   by transfer simp
 
 lemma sdiv_smod_id:
   \<open>(a sdiv b) * b + (a smod b) = a\<close>
   for a b :: \<open>'a::len word\<close>
   by (cases \<open>sint a < 0\<close>; cases \<open>sint b < 0\<close>) (simp_all add: signed_modulo_int_def sdiv_word_def smod_word_def)
 
 (* Tests *)
 lemma
   "( 4 :: word32) sdiv  4 =  1"
   "(-4 :: word32) sdiv  4 = -1"
   "(-3 :: word32) sdiv  4 =  0"
   "( 3 :: word32) sdiv -4 =  0"
   "(-3 :: word32) sdiv -4 =  0"
   "(-5 :: word32) sdiv -4 =  1"
   "( 5 :: word32) sdiv -4 = -1"
   by (simp_all add: sdiv_word_def signed_divide_int_def)
 
 lemma
   "( 4 :: word32) smod  4 =   0"
   "( 3 :: word32) smod  4 =   3"
   "(-3 :: word32) smod  4 =  -3"
   "( 3 :: word32) smod -4 =   3"
   "(-3 :: word32) smod -4 =  -3"
   "(-5 :: word32) smod -4 =  -1"
   "( 5 :: word32) smod -4 =   1"
   by (simp_all add: smod_word_def signed_modulo_int_def signed_divide_int_def)
 
 
 (* Count leading zeros  *)
 definition
   word_clz :: "'a::len word \<Rightarrow> nat"
 where
   "word_clz w \<equiv> length (takeWhile Not (to_bl w))"
 
 (* Count trailing zeros  *)
 definition
   word_ctz :: "'a::len word \<Rightarrow> nat"
 where
   "word_ctz w \<equiv> length (takeWhile Not (rev (to_bl w)))"
 
 definition
   word_log2 :: "'a::len word \<Rightarrow> nat"
 where
   "word_log2 (w::'a::len word) \<equiv> size w - 1 - word_clz w"
 
 
 (* Bit population count. Equivalent of __builtin_popcount. *)
 definition
   pop_count :: "('a::len) word \<Rightarrow> nat"
 where
   "pop_count w \<equiv> length (filter id (to_bl w))"
 
 
 (* Sign extension from bit n *)
 
 definition
   sign_extend :: "nat \<Rightarrow> 'a::len word \<Rightarrow> 'a word"
 where
   "sign_extend n w \<equiv> if w !! n then w || ~~ (mask n) else w && mask n"
 
 lemma sign_extend_eq_signed_take_bit:
   \<open>sign_extend = signed_take_bit\<close>
 proof (rule ext)+
   fix n and w :: \<open>'a::len word\<close>
   show \<open>sign_extend n w = signed_take_bit n w\<close>
   proof (rule bit_word_eqI)
     fix q
     assume \<open>q < LENGTH('a)\<close>
     then show \<open>bit (sign_extend n w) q \<longleftrightarrow> bit (signed_take_bit n w) q\<close>
       by (auto simp add: test_bit_eq_bit bit_signed_take_bit_iff
         sign_extend_def bit_and_iff bit_or_iff bit_not_iff bit_mask_iff not_less
         exp_eq_0_imp_not_bit not_le min_def)
   qed
 qed
 
 definition
   sign_extended :: "nat \<Rightarrow> 'a::len word \<Rightarrow> bool"
 where
   "sign_extended n w \<equiv> \<forall>i. n < i \<longrightarrow> i < size w \<longrightarrow> w !! i = w !! n"
 
 
 lemma ptr_add_0 [simp]:
   "ptr_add ref 0 = ref "
   unfolding ptr_add_def by simp
 
 lemma shiftl_power:
   "(shiftl1 ^^ x) (y::'a::len word) = 2 ^ x * y"
   apply (induct x)
    apply simp
   apply (simp add: shiftl1_2t)
   done
 
 lemmas of_bl_reasoning = to_bl_use_of_bl of_bl_append
 
 lemma uint_of_bl_is_bl_to_bin_drop:
   "length (dropWhile Not l) \<le> LENGTH('a) \<Longrightarrow> uint (of_bl l :: 'a::len word) = bl_to_bin l"
   apply transfer
   apply (simp add: take_bit_eq_mod)
   apply (rule Divides.mod_less)
    apply (rule bl_to_bin_ge0)
   using bl_to_bin_lt2p_drop apply (rule order.strict_trans2)
   apply simp
   done
 
 corollary uint_of_bl_is_bl_to_bin:
   "length l\<le>LENGTH('a) \<Longrightarrow> uint ((of_bl::bool list\<Rightarrow> ('a :: len) word) l) = bl_to_bin l"
   apply(rule uint_of_bl_is_bl_to_bin_drop)
   using le_trans length_dropWhile_le by blast
 
 lemma bin_to_bl_or:
   "bin_to_bl n (a OR b) = map2 (\<or>) (bin_to_bl n a) (bin_to_bl n b)"
   using bl_or_aux_bin[where n=n and v=a and w=b and bs="[]" and cs="[]"]
   by simp
 
 lemma word_ops_nth [simp]:
   shows
   word_or_nth:  "(x || y) !! n = (x !! n \<or> y !! n)" and
   word_and_nth: "(x && y) !! n = (x !! n \<and> y !! n)" and
   word_xor_nth: "(x xor y) !! n = (x !! n \<noteq> y !! n)"
   by ((cases "n < size x",
       auto dest: test_bit_size simp: word_ops_nth_size word_size)[1])+
 
 (* simp del to avoid warning on the simp add in iff *)
 declare test_bit_1 [simp del, iff]
 
 (* test: *)
 lemma "1 < (1024::32 word) \<and> 1 \<le> (1024::32 word)" by simp
 
 lemma and_not_mask:
   "w AND NOT (mask n) = (w >> n) << n"
   for w :: \<open>'a::len word\<close>
   apply (rule word_eqI)
   apply (simp add : word_ops_nth_size word_size)
   apply (simp add : nth_shiftr nth_shiftl)
   by auto
 
 lemma and_mask:
   "w AND mask n = (w << (size w - n)) >> (size w - n)"
   for w :: \<open>'a::len word\<close>
   apply (rule word_eqI)
   apply (simp add : word_ops_nth_size word_size)
   apply (simp add : nth_shiftr nth_shiftl)
   by auto
 
 lemma AND_twice [simp]:
   "(w && m) && m = w && m"
-  by (simp add: word_eqI)
+  by (fact and.right_idem)
 
 lemma word_combine_masks:
   "w && m = z \<Longrightarrow> w && m' = z' \<Longrightarrow> w && (m || m') = (z || z')"
   by (auto simp: word_eq_iff)
 
 lemma nth_w2p_same:
   "(2^n :: 'a :: len word) !! n = (n < LENGTH('a))"
   by (simp add : nth_w2p)
 
 lemma p2_gt_0:
   "(0 < (2 ^ n :: 'a :: len word)) = (n < LENGTH('a))"
   apply (simp add : word_gt_0)
   apply safe
    apply (erule swap)
    apply (rule word_eqI)
    apply (simp add : nth_w2p)
   apply (drule word_eqD)
   apply simp
   apply (erule notE)
   apply (erule nth_w2p_same [THEN iffD2])
   done
 
 lemmas uint_2p_alt = uint_2p [unfolded p2_gt_0]
 
 lemma shiftr_div_2n_w: "n < size w \<Longrightarrow> w >> n = w div (2^n :: 'a :: len word)"
   apply (unfold word_div_def)
   apply (simp add : uint_2p_alt word_size)
   apply (rule word_uint.Rep_inverse' [THEN sym])
   apply (rule shiftr_div_2n)
   done
 
 lemmas less_def = less_eq [symmetric]
 lemmas le_def = not_less [symmetric, where ?'a = nat]
 
 lemmas p2_eq_0 [simp] = trans [OF eq_commute
   iffD2 [OF Not_eq_iff p2_gt_0, folded le_def, unfolded word_gt_0 not_not]]
 
 lemma neg_mask_is_div':
   "n < size w \<Longrightarrow> w AND NOT (mask n) = ((w div (2 ^ n)) * (2 ^ n))"
   for w :: \<open>'a::len word\<close>
   by (simp add : and_not_mask shiftr_div_2n_w shiftl_t2n word_size)
 
 lemma neg_mask_is_div:
   "w AND NOT (mask n) = (w div 2^n) * 2^n"
   for w :: \<open>'a::len word\<close>
   apply (cases "n < size w")
    apply (erule neg_mask_is_div')
   apply (simp add: word_size)
   apply (frule p2_gt_0 [THEN Not_eq_iff [THEN iffD2], THEN iffD2])
   apply (simp add: word_gt_0  del: p2_eq_0)
   apply (rule word_eqI)
   apply (simp add: word_ops_nth_size word_size)
   done
 
 lemma and_mask_arith':
   "0 < n \<Longrightarrow> w AND mask n = (w * 2^(size w - n)) div 2^(size w - n)"
   for w :: \<open>'a::len word\<close>
   by (simp add: and_mask shiftr_div_2n_w shiftl_t2n word_size mult.commute)
 
 lemmas p2len = iffD2 [OF p2_eq_0 order_refl]
 
 lemma and_mask_arith:
   "w AND mask n = (w * 2^(size w - n)) div 2^(size w - n)"
   for w :: \<open>'a::len word\<close>
   apply (cases "0 < n")
    apply (auto elim!: and_mask_arith')
   apply (simp add: word_size)
   done
 
 lemma mask_2pm1: "mask n = 2 ^ n - (1 :: 'a::len word)"
   by (fact mask_eq_decr_exp)
 
 lemma add_mask_fold:
   "x + 2 ^ n - 1 = x + mask n"
   for x :: \<open>'a::len word\<close>
   by (simp add: mask_eq_decr_exp)
 
 lemma word_and_mask_le_2pm1: "w && mask n \<le> 2 ^ n - 1"
   by (simp add: mask_2pm1[symmetric] word_and_le1)
 
 lemma is_aligned_AND_less_0:
   "u && mask n = 0 \<Longrightarrow> v < 2^n \<Longrightarrow> u && v = 0"
   apply (drule less_mask_eq)
   apply (simp add: mask_2pm1)
   apply (rule word_eqI)
   apply (clarsimp simp add: word_size)
   apply (drule_tac x=na in word_eqD)
   apply (drule_tac x=na in word_eqD)
   apply simp
   done
 
 lemma le_shiftr1:
   "u <= v \<Longrightarrow> shiftr1 u <= shiftr1 v"
   apply (unfold word_le_def shiftr1_eq word_ubin.eq_norm)
   apply (unfold bin_rest_trunc_i
                 trans [OF bintrunc_bintrunc_l word_ubin.norm_Rep,
                           unfolded word_ubin.norm_Rep,
                        OF order_refl [THEN le_SucI]])
   apply (case_tac "uint u" rule: bin_exhaust)
   apply (rename_tac bs bit)
   apply (case_tac "uint v" rule: bin_exhaust)
   apply (rename_tac bs' bit')
   apply (case_tac "bit")
    apply (case_tac "bit'", auto simp: less_eq_int_code)[1]
   apply (case_tac bit')
     apply (simp add: less_eq_int_code)
   apply (simp add: less_eq_int_code)
   done
 
 lemma le_shiftr:
   "u \<le> v \<Longrightarrow> u >> (n :: nat) \<le> (v :: 'a :: len word) >> n"
   apply (unfold shiftr_def)
   apply (induct_tac "n")
    apply auto
   apply (erule le_shiftr1)
   done
 
 lemma shiftr_mask_le:
   "n <= m \<Longrightarrow> mask n >> m = (0 :: 'a::len word)"
   apply (rule word_eqI)
   apply (simp add: word_size nth_shiftr)
   done
 
 lemmas shiftr_mask = order_refl [THEN shiftr_mask_le, simp]
 
 lemma word_leI:
   "(\<And>n.  \<lbrakk>n < size (u::'a::len word); u !! n \<rbrakk> \<Longrightarrow> (v::'a::len word) !! n) \<Longrightarrow> u <= v"
   apply (rule xtr4)
    apply (rule word_and_le2)
   apply (rule word_eqI)
   apply (simp add: word_ao_nth)
   apply safe
     apply assumption
    apply (erule_tac [2] asm_rl)
   apply (unfold word_size)
   by auto
 
 lemma le_mask_iff:
   "(w \<le> mask n) = (w >> n = 0)"
   for w :: \<open>'a::len word\<close>
   apply safe
    apply (rule word_le_0_iff [THEN iffD1])
    apply (rule xtr3)
     apply (erule_tac [2] le_shiftr)
    apply simp
   apply (rule word_leI)
   apply (rename_tac n')
   apply (drule_tac x = "n' - n" in word_eqD)
   apply (simp add : nth_shiftr word_size)
   apply (case_tac "n <= n'")
   by auto
 
 lemma and_mask_eq_iff_shiftr_0:
   "(w AND mask n = w) = (w >> n = 0)"
   for w :: \<open>'a::len word\<close>
   apply (unfold test_bit_eq_iff [THEN sym])
   apply (rule iffI)
    apply (rule ext)
    apply (rule_tac [2] ext)
    apply (auto simp add : word_ao_nth nth_shiftr)
     apply (drule arg_cong)
     apply (drule iffD2)
      apply assumption
     apply (simp add : word_ao_nth)
    prefer 2
    apply (simp add : word_size test_bit_bin)
   apply (drule_tac f = "%u. u !! (x - n)" in arg_cong)
   apply (simp add : nth_shiftr)
   apply (case_tac "n <= x")
    apply auto
   done
 
 lemmas and_mask_eq_iff_le_mask = trans
   [OF and_mask_eq_iff_shiftr_0 le_mask_iff [THEN sym]]
 
 lemma mask_shiftl_decompose:
   "mask m << n = mask (m + n) && ~~ (mask n)"
   by (auto intro!: word_eqI simp: and_not_mask nth_shiftl nth_shiftr word_size)
 
 lemma one_bit_shiftl: "set_bit 0 n True = (1 :: 'a :: len word) << n"
   apply (rule word_eqI)
   apply (auto simp add: test_bit_set_gen nth_shiftl word_size
               simp del: word_set_bit_0 shiftl_1)
   done
 
 lemmas one_bit_pow = trans [OF one_bit_shiftl shiftl_1]
 
 lemmas bin_sc_minus_simps =
   bin_sc_simps (2,3,4) [THEN [2] trans, OF bin_sc_minus [THEN sym]]
 
 lemma NOT_eq:
   "NOT (x :: 'a :: len word) = - x - 1"
   apply (cut_tac x = "x" in word_add_not)
   apply (drule add.commute [THEN trans])
   apply (drule eq_diff_eq [THEN iffD2])
   by simp
 
 lemma NOT_mask: "NOT (mask n :: 'a::len word) = - (2 ^ n)"
   by (simp add : NOT_eq mask_2pm1)
 
 lemma le_m1_iff_lt: "(x > (0 :: 'a :: len word)) = ((y \<le> x - 1) = (y < x))"
   by uint_arith
 
 lemmas gt0_iff_gem1 = iffD1 [OF iffD1 [OF iff_left_commute le_m1_iff_lt] order_refl]
 
 lemmas power_2_ge_iff = trans [OF gt0_iff_gem1 [THEN sym] p2_gt_0]
 
 lemma le_mask_iff_lt_2n:
   "n < len_of TYPE ('a) = (((w :: 'a :: len word) \<le> mask n) = (w < 2 ^ n))"
   unfolding mask_2pm1 by (rule trans [OF p2_gt_0 [THEN sym] le_m1_iff_lt])
 
 lemmas mask_lt_2pn =
   le_mask_iff_lt_2n [THEN iffD1, THEN iffD1, OF _ order_refl]
 
 lemma bang_eq:
   fixes x :: "'a::len word"
   shows "(x = y) = (\<forall>n. x !! n = y !! n)"
   by (subst test_bit_eq_iff[symmetric]) fastforce
 
 lemma word_unat_power:
   "(2 :: 'a :: len word) ^ n = of_nat (2 ^ n)"
   by simp
 
 lemma of_nat_mono_maybe:
   assumes xlt: "x < 2 ^ len_of TYPE ('a)"
   shows   "y < x \<Longrightarrow> of_nat y < (of_nat x :: 'a :: len word)"
   apply (subst word_less_nat_alt)
   apply (subst unat_of_nat)+
   apply (subst mod_less)
    apply (erule order_less_trans [OF _ xlt])
   apply (subst mod_less [OF xlt])
   apply assumption
   done
 
 lemma shiftl_over_and_dist:
   fixes a::"'a::len word"
   shows "(a AND b) << c = (a << c) AND (b << c)"
   apply(rule word_eqI)
   apply(simp add: word_ao_nth nth_shiftl, safe)
   done
 
 lemma shiftr_over_and_dist:
   fixes a::"'a::len word"
   shows "a AND b >> c = (a >> c) AND (b >> c)"
   apply(rule word_eqI)
   apply(simp add:nth_shiftr word_ao_nth)
   done
 
 lemma sshiftr_over_and_dist:
   fixes a::"'a::len word"
   shows "a AND b >>> c = (a >>> c) AND (b >>> c)"
   apply(rule word_eqI)
   apply(simp add:nth_sshiftr word_ao_nth word_size)
   done
 
 lemma shiftl_over_or_dist:
   fixes a::"'a::len word"
   shows "a OR b << c = (a << c) OR (b << c)"
   apply(rule word_eqI)
   apply(simp add:nth_shiftl word_ao_nth, safe)
   done
 
 lemma shiftr_over_or_dist:
   fixes a::"'a::len word"
   shows "a OR b >> c = (a >> c) OR (b >> c)"
   apply(rule word_eqI)
   apply(simp add:nth_shiftr word_ao_nth)
   done
 
 lemma sshiftr_over_or_dist:
   fixes a::"'a::len word"
   shows "a OR b >>> c = (a >>> c) OR (b >>> c)"
   apply(rule word_eqI)
   apply(simp add:nth_sshiftr word_ao_nth word_size)
   done
 
 lemmas shift_over_ao_dists =
   shiftl_over_or_dist shiftr_over_or_dist
   sshiftr_over_or_dist shiftl_over_and_dist
   shiftr_over_and_dist sshiftr_over_and_dist
 
 lemma shiftl_shiftl:
   fixes a::"'a::len word"
   shows "a << b << c = a << (b + c)"
   apply(rule word_eqI)
   apply(auto simp:word_size nth_shiftl add.commute add.left_commute)
   done
 
 lemma shiftr_shiftr:
   fixes a::"'a::len word"
   shows "a >> b >> c = a >> (b + c)"
   apply(rule word_eqI)
   apply(simp add:word_size nth_shiftr add.left_commute add.commute)
   done
 
 lemma shiftl_shiftr1:
   fixes a::"'a::len word"
   shows "c \<le> b \<Longrightarrow> a << b >> c = a AND (mask (size a - b)) << (b - c)"
   apply(rule word_eqI)
   apply(auto simp:nth_shiftr nth_shiftl word_size word_ao_nth)
   done
 
 lemma shiftl_shiftr2:
   fixes a::"'a::len word"
   shows "b < c \<Longrightarrow> a << b >> c = (a >> (c - b)) AND (mask (size a - c))"
   apply(rule word_eqI)
   apply(auto simp:nth_shiftr nth_shiftl word_size word_ao_nth)
   done
 
 lemma shiftr_shiftl1:
   fixes a::"'a::len word"
   shows "c \<le> b \<Longrightarrow> a >> b << c = (a >> (b - c)) AND (NOT (mask c))"
   apply(rule word_eqI)
   apply(auto simp:nth_shiftr nth_shiftl word_size word_ops_nth_size)
   done
 
 lemma shiftr_shiftl2:
   fixes a::"'a::len word"
   shows "b < c \<Longrightarrow> a >> b << c = (a << (c - b)) AND (NOT (mask c))"
   apply(rule word_eqI)
   apply(auto simp:nth_shiftr nth_shiftl word_size word_ops_nth_size)
   done
 
 lemmas multi_shift_simps =
   shiftl_shiftl shiftr_shiftr
   shiftl_shiftr1 shiftl_shiftr2
   shiftr_shiftl1 shiftr_shiftl2
 
 lemma word_and_max_word:
   fixes a::"'a::len word"
   shows "x = max_word \<Longrightarrow> a AND x = a"
   by simp
 
 lemma word_and_full_mask_simp:
   \<open>x && Bit_Operations.mask LENGTH('a) = x\<close> for x :: \<open>'a::len word\<close>
 proof (rule bit_eqI)
   fix n
   assume \<open>2 ^ n \<noteq> (0 :: 'a word)\<close>
   then have \<open>n < LENGTH('a)\<close>
     by simp
   then show \<open>bit (x && Bit_Operations.mask LENGTH('a)) n \<longleftrightarrow> bit x n\<close>
     by (simp add: bit_and_iff bit_mask_iff)
 qed
 	
 lemma word8_and_max_simp:
   \<open>x && 0xFF = x\<close> for x :: \<open>8 word\<close>
   using word_and_full_mask_simp [of x]
   by (simp add: numeral_eq_Suc mask_Suc_exp)
 	
 lemma word16_and_max_simp:
   \<open>x && 0xFFFF = x\<close> for x :: \<open>16 word\<close>
   using word_and_full_mask_simp [of x]
   by (simp add: numeral_eq_Suc mask_Suc_exp)
 	
 lemma word32_and_max_simp:
   \<open>x && 0xFFFFFFFF = x\<close> for x :: \<open>32 word\<close>
   using word_and_full_mask_simp [of x]
   by (simp add: numeral_eq_Suc mask_Suc_exp)
 	
 lemma word64_and_max_simp:
   \<open>x && 0xFFFFFFFFFFFFFFFF = x\<close> for x :: \<open>64 word\<close>
   using word_and_full_mask_simp [of x]
   by (simp add: numeral_eq_Suc mask_Suc_exp)
 	
 lemmas word_and_max_simps =
   word8_and_max_simp
   word16_and_max_simp
   word32_and_max_simp
   word64_and_max_simp
 
 lemma word_and_1_bl:
   fixes x::"'a::len word"
   shows "(x AND 1) = of_bl [x !! 0]"
   by (simp add: mod_2_eq_odd test_bit_word_eq and_one_eq)
 
 lemma word_1_and_bl:
   fixes x::"'a::len word"
   shows "(1 AND x) = of_bl [x !! 0]"
   by (simp add: mod_2_eq_odd test_bit_word_eq one_and_eq)
 
 lemma scast_scast_id [simp]:
   "scast (scast x :: ('a::len) signed word) = (x :: 'a word)"
   "scast (scast y :: ('a::len) word) = (y :: 'a signed word)"
   by (auto simp: is_up scast_up_scast_id)
 
 lemma scast_ucast_id [simp]:
     "scast (ucast (x :: 'a::len word) :: 'a signed word) = x"
   by (metis down_cast_same is_down len_signed order_refl scast_scast_id(1))
 
 lemma ucast_scast_id [simp]:
     "ucast (scast (x :: 'a::len signed word) :: 'a word) = x"
   by (metis scast_scast_id(2) scast_ucast_id)
 
 lemma scast_of_nat [simp]:
     "scast (of_nat x :: 'a::len signed word) = (of_nat x :: 'a word)"
   by transfer simp
 
 lemma ucast_of_nat:
   "is_down (ucast :: 'a :: len word \<Rightarrow> 'b :: len word)
     \<Longrightarrow> ucast (of_nat n :: 'a word) = (of_nat n :: 'b word)"
   by transfer simp
 
 (* shortcut for some specific lengths *)
 lemma word_fixed_sint_1[simp]:
   "sint (1::8 word) = 1"
   "sint (1::16 word) = 1"
   "sint (1::32 word) = 1"
   "sint (1::64 word) = 1"
   by (auto simp: sint_word_ariths)
 
 lemma word_sint_1 [simp]:
   "sint (1::'a::len word) = (if LENGTH('a) = 1 then -1 else 1)"
   by (cases \<open>LENGTH('a)\<close>)
     (simp_all add: not_le sint_uint le_Suc_eq sbintrunc_minus_simps)
 
 lemma scast_1':
   "(scast (1::'a::len word) :: 'b::len word) =
    (word_of_int (sbintrunc (LENGTH('a::len) - Suc 0) (1::int)))"
   by transfer simp
 
 lemma scast_1:
   "(scast (1::'a::len word) :: 'b::len word) = (if LENGTH('a) = 1 then -1 else 1)"
   by (fact signed_1)
 
 lemma scast_eq_scast_id [simp]:
   "((scast (a :: 'a::len signed word) :: 'a word) = scast b) = (a = b)"
   by (metis ucast_scast_id)
 
 lemma ucast_eq_ucast_id [simp]:
   "((ucast (a :: 'a::len word) :: 'a signed word) = ucast b) = (a = b)"
   by (metis scast_ucast_id)
 
 lemma scast_ucast_norm [simp]:
   "(ucast (a :: 'a::len word) = (b :: 'a signed word)) = (a = scast b)"
   "((b :: 'a signed word) = ucast (a :: 'a::len word)) = (a = scast b)"
   by (metis scast_ucast_id ucast_scast_id)+
 
 lemma of_bl_drop:
   "of_bl (drop n xs) = (of_bl xs && mask (length xs - n))"
   apply (clarsimp simp: bang_eq test_bit_of_bl rev_nth cong: rev_conj_cong)
   apply (safe; simp add: word_size to_bl_nth)
   done
 
 lemma of_int_uint:
   "of_int (uint x) = x"
   by (fact word_of_int_uint)
 
 lemma shiftr_mask2:
   "n \<le> LENGTH('a) \<Longrightarrow> (mask n >> m :: ('a :: len) word) = mask (n - m)"
   apply (rule word_eqI)
   apply (simp add: nth_shiftr word_size)
   apply arith
   done
 
 corollary word_plus_and_or_coroll:
   "x && y = 0 \<Longrightarrow> x + y = x || y"
   using word_plus_and_or[where x=x and y=y]
   by simp
 
 corollary word_plus_and_or_coroll2:
   "(x && w) + (x && ~~ w) = x"
   apply (subst word_plus_and_or_coroll)
    apply (rule word_eqI, simp add: word_size word_ops_nth_size)
   apply (rule word_eqI, simp add: word_size word_ops_nth_size)
   apply blast
   done
 
 lemma less_le_mult_nat':
   "w * c < b * c ==> 0 \<le> c ==> Suc w * c \<le> b * (c::nat)"
   apply (rule mult_right_mono)
    apply (rule Suc_leI)
    apply (erule (1) mult_right_less_imp_less)
   apply assumption
   done
 
 lemmas less_le_mult_nat = less_le_mult_nat'[simplified distrib_right, simplified]
 
 (* FIXME: these should eventually be moved to HOL/Word. *)
 lemmas extra_sle_sless_unfolds [simp] =
     word_sle_eq[where a=0 and b=1]
     word_sle_eq[where a=0 and b="numeral n"]
     word_sle_eq[where a=1 and b=0]
     word_sle_eq[where a=1 and b="numeral n"]
     word_sle_eq[where a="numeral n" and b=0]
     word_sle_eq[where a="numeral n" and b=1]
     word_sless_alt[where a=0 and b=1]
     word_sless_alt[where a=0 and b="numeral n"]
     word_sless_alt[where a=1 and b=0]
     word_sless_alt[where a=1 and b="numeral n"]
     word_sless_alt[where a="numeral n" and b=0]
     word_sless_alt[where a="numeral n" and b=1]
   for n
 
 
 lemma to_bl_1:
   "to_bl (1::'a::len word) = replicate (LENGTH('a) - 1) False @ [True]"
   by (rule nth_equalityI) (auto simp add: to_bl_unfold nth_append rev_nth bit_1_iff not_less not_le)
 
 lemma list_of_false:
   "True \<notin> set xs \<Longrightarrow> xs = replicate (length xs) False"
   by (induct xs, simp_all)
 
 lemma eq_zero_set_bl:
   "(w = 0) = (True \<notin> set (to_bl w))"
   using list_of_false word_bl.Rep_inject by fastforce
 
 lemma diff_diff_less:
   "(i < m - (m - (n :: nat))) = (i < m \<and> i < n)"
   by auto
 
 lemma pop_count_0[simp]:
   "pop_count 0 = 0"
   by (clarsimp simp:pop_count_def)
 
 lemma pop_count_1[simp]:
   "pop_count 1 = 1"
   by (clarsimp simp:pop_count_def to_bl_1)
 
 lemma pop_count_0_imp_0:
   "(pop_count w = 0) = (w = 0)"
   apply (rule iffI)
    apply (clarsimp simp:pop_count_def)
    apply (subst (asm) filter_empty_conv)
    apply (clarsimp simp:eq_zero_set_bl)
    apply fast
   apply simp
   done
 
 end
diff --git a/thys/Word_Lib/Word_Next.thy b/thys/Word_Lib/Word_Next.thy
--- a/thys/Word_Lib/Word_Next.thy
+++ b/thys/Word_Lib/Word_Next.thy
@@ -1,118 +1,130 @@
 (* SPDX-License-Identifier: BSD-3-Clause *)
 
 section\<open>Increment and Decrement Machine Words Without Wrap-Around\<close>
 
 theory Word_Next
 imports
   Aligned
 begin
 
-text\<open>Previous and next words addresses, without wrap around.\<close>
-
-definition word_next :: "'a::len word \<Rightarrow> 'a::len word" where
-  "word_next a \<equiv> if a = max_word then max_word else a + 1"
-
-definition word_prev :: "'a::len word \<Rightarrow> 'a::len word" where
-  "word_prev a \<equiv> if a = 0 then 0 else a - 1"
-
-text\<open>Examples:\<close>
-
-lemma [code]:
-  \<open>Word.the_int (word_next w :: 'a::len word) =
-    (if w = - 1 then Word.the_int w else Word.the_int w + 1)\<close>
-  apply (simp add: word_next_def) apply transfer
-  apply (simp add: take_bit_minus_one_eq_mask mask_eq_exp_minus_1)
-  subgoal for k
-    using take_bit_incr_eq [of \<open>LENGTH('a)\<close> k]
-    apply (simp add: ac_simps)
-    done
+lemma take_bit_eq_mask_iff:
+  \<open>take_bit n k = mask n \<longleftrightarrow> take_bit n (k + 1) = 0\<close>
+  for k :: int
+  apply auto
+   apply (subst take_bit_add [symmetric])
+   apply (simp add: mask_eq_exp_minus_1)
+  apply (metis bintrunc_bintrunc diff_0 diff_add_cancel diff_minus_eq_add mask_eq_take_bit_minus_one take_bit_diff)
   done
 
-lemma [code]:
-  \<open>Word.the_int (word_prev w :: 'a::len word) =
-    (if w = 0 then Word.the_int w else Word.the_int w - 1)\<close>
-  apply (simp add: word_prev_def)
-  apply transfer
-  subgoal for k
-    apply rule
-    apply (subst take_bit_diff [symmetric])
-    using take_bit_int_less_exp [of \<open>LENGTH('a)\<close> k]
-    apply (simp add: take_bit_int_eq_self_iff less_le)
-    done
-  done
-
-lemma "word_next (2:: 8 word) = 3" by eval
-lemma "word_next (255:: 8 word) = 255" by eval
-lemma "word_prev (2:: 8 word) = 1" by eval
-lemma "word_prev (0:: 8 word) = 0" by eval
+lemma take_bit_eq_mask_iff_exp_dvd:
+  \<open>take_bit n k = mask n \<longleftrightarrow> 2 ^ n dvd k + 1\<close>
+  for k :: int
+  by (simp add: take_bit_eq_mask_iff flip: take_bit_eq_0_iff)
 
 lemma plus_one_helper[elim!]:
   "x < n + (1 :: 'a :: len word) \<Longrightarrow> x \<le> n"
   apply (simp add: word_less_nat_alt word_le_nat_alt field_simps)
   apply (case_tac "1 + n = 0")
-   apply simp
+   apply simp_all
   apply (subst(asm) unatSuc, assumption)
   apply arith
   done
 
 lemma plus_one_helper2:
   "\<lbrakk> x \<le> n; n + 1 \<noteq> 0 \<rbrakk> \<Longrightarrow> x < n + (1 :: 'a :: len word)"
   by (simp add: word_less_nat_alt word_le_nat_alt field_simps
                 unatSuc)
 
 lemma less_x_plus_1:
   fixes x :: "'a :: len word" shows
   "x \<noteq> max_word \<Longrightarrow> (y < (x + 1)) = (y < x \<or> y = x)"
   apply (rule iffI)
    apply (rule disjCI)
    apply (drule plus_one_helper)
    apply simp
   apply (subgoal_tac "x < x + 1")
    apply (erule disjE, simp_all)
   apply (rule plus_one_helper2 [OF order_refl])
   apply (rule notI, drule max_word_wrap)
   apply simp
   done
 
-
-lemma word_Suc_leq: fixes k::"'a::len word" shows "k \<noteq> max_word \<Longrightarrow> x < k + 1 \<longleftrightarrow> x \<le> k"
+lemma word_Suc_leq:
+  fixes k::"'a::len word" shows "k \<noteq> max_word \<Longrightarrow> x < k + 1 \<longleftrightarrow> x \<le> k"
   using less_x_plus_1 word_le_less_eq by auto
 
-lemma word_Suc_le: fixes k::"'a::len word" shows "x \<noteq> max_word \<Longrightarrow> x + 1 \<le> k \<longleftrightarrow> x < k"
+lemma word_Suc_le:
+   fixes k::"'a::len word" shows "x \<noteq> max_word \<Longrightarrow> x + 1 \<le> k \<longleftrightarrow> x < k"
   by (meson not_less word_Suc_leq)
 
 lemma word_lessThan_Suc_atMost:
   \<open>{..< k + 1} = {..k}\<close> if \<open>k \<noteq> - 1\<close> for k :: \<open>'a::len word\<close>
   using that by (simp add: lessThan_def atMost_def word_Suc_leq)
 
 lemma word_atLeastLessThan_Suc_atLeastAtMost:
   \<open>{l ..< u + 1} = {l..u}\<close> if \<open>u \<noteq> - 1\<close> for l :: \<open>'a::len word\<close>
   using that by (simp add: atLeastAtMost_def atLeastLessThan_def word_lessThan_Suc_atMost)
 
 lemma word_atLeastAtMost_Suc_greaterThanAtMost:
   \<open>{m<..u} = {m + 1..u}\<close> if \<open>m \<noteq> - 1\<close> for m :: \<open>'a::len word\<close>
   using that by (simp add: greaterThanAtMost_def greaterThan_def atLeastAtMost_def atLeast_def word_Suc_le)
 
 lemma word_atLeastLessThan_Suc_atLeastAtMost_union:
   fixes l::"'a::len word"
   assumes "m \<noteq> max_word" and "l \<le> m" and "m \<le> u"
   shows "{l..m} \<union> {m+1..u} = {l..u}"
   proof -
   from ivl_disj_un_two(8)[OF assms(2) assms(3)] have "{l..u} = {l..m} \<union> {m<..u}" by blast
   with assms show ?thesis by(simp add: word_atLeastAtMost_Suc_greaterThanAtMost)
   qed
 
 lemma max_word_less_eq_iff [simp]:
   \<open>- 1 \<le> w \<longleftrightarrow> w = - 1\<close> for w :: \<open>'a::len word\<close>
-  by (auto simp add: le_less)  
+  by (fact word_order.extremum_unique)
+
+text \<open>Previous and next words addresses, without wrap around.\<close>
+
+lift_definition word_next :: \<open>'a::len word \<Rightarrow> 'a word\<close>
+  is \<open>\<lambda>k. if 2 ^ LENGTH('a) dvd k + 1 then - 1 else k + 1\<close>
+  by (simp flip: take_bit_eq_0_iff) (metis take_bit_add)
+
+lift_definition word_prev :: \<open>'a::len word \<Rightarrow> 'a word\<close>
+  is \<open>\<lambda>k. if 2 ^ LENGTH('a) dvd k then 0 else k - 1\<close>
+  by (simp flip: take_bit_eq_0_iff) (metis take_bit_diff)
+
+lemma word_next_unfold:
+  \<open>word_next w = (if w = - 1 then - 1 else w + 1)\<close>
+  by transfer (simp add: take_bit_minus_one_eq_mask flip: take_bit_eq_mask_iff_exp_dvd)
+
+lemma word_prev_unfold:
+  \<open>word_prev w = (if w = 0 then 0 else w - 1)\<close>
+  by transfer (simp flip: take_bit_eq_0_iff)
+
+lemma [code]:
+  \<open>Word.the_int (word_next w :: 'a::len word) =
+    (if w = - 1 then Word.the_int w else Word.the_int w + 1)\<close>
+  by transfer
+    (simp add: take_bit_minus_one_eq_mask mask_eq_exp_minus_1 take_bit_incr_eq flip: take_bit_eq_mask_iff_exp_dvd) 
+
+lemma [code]:
+  \<open>Word.the_int (word_prev w :: 'a::len word) =
+    (if w = 0 then Word.the_int w else Word.the_int w - 1)\<close>
+  by transfer (simp add: take_bit_eq_0_iff take_bit_decr_eq)
+
+text\<open>Examples:\<close>
+
+lemma "word_next (2:: 8 word) = 3" by eval
+lemma "word_next (255:: 8 word) = 255" by eval
+lemma "word_prev (2:: 8 word) = 1" by eval
+lemma "word_prev (0:: 8 word) = 0" by eval
 
 lemma word_adjacent_union:
   "word_next e = s' \<Longrightarrow> s \<le> e \<Longrightarrow> s' \<le> e' \<Longrightarrow> {s..e} \<union> {s'..e'} = {s .. e'}"
-  apply (simp add: word_next_def ivl_disj_un_two_touch split: if_splits)
+  apply (simp add: word_next_unfold ivl_disj_un_two_touch split: if_splits)
   apply (drule sym)
   apply simp
   apply (subst word_atLeastLessThan_Suc_atLeastAtMost_union)
      apply (simp_all add: word_Suc_le)
   done
 
 end