diff --git a/thys/Native_Word/Word_Type_Copies.thy b/thys/Native_Word/Word_Type_Copies.thy --- a/thys/Native_Word/Word_Type_Copies.thy +++ b/thys/Native_Word/Word_Type_Copies.thy @@ -1,341 +1,341 @@ (* Title: Word_Type_Copies.thy Author: Florian Haftmann, TU Muenchen *) chapter \Systematic approach towards type copies of word type\ theory Word_Type_Copies imports "HOL-Library.Word" "Word_Lib.Most_significant_bit" "Word_Lib.Least_significant_bit" "Word_Lib.Generic_set_bit" Code_Target_Word_Base begin lemma int_of_integer_unsigned_eq [simp]: \int_of_integer (unsigned w) = uint w\ by transfer simp lemma int_of_integer_signed_eq [simp]: \int_of_integer (signed w) = sint w\ by transfer simp lemma word_of_int_of_integer_eq [simp]: \word_of_int (int_of_integer k) = word_of_integer k\ by (simp add: word_of_integer.rep_eq) text \The lifting machinery is not localized, hence the abstract proofs are carried out using morphisms.\ locale word_type_copy = fixes of_word :: \'b::len word \ 'a\ and word_of :: \'a \ 'b word\ assumes type_definition: \type_definition word_of of_word UNIV\ begin lemma word_of_word: \word_of (of_word w) = w\ using type_definition by (simp add: type_definition_def) lemma of_word_of [code abstype]: \of_word (word_of p) = p\ \ \Use an abstract type for code generation to disable pattern matching on \<^term>\of_word\.\ using type_definition by (simp add: type_definition_def) lemma word_of_eqI: \p = q\ if \word_of p = word_of q\ proof - from that have \of_word (word_of p) = of_word (word_of q)\ by simp then show ?thesis by (simp add: of_word_of) qed lemma eq_iff_word_of: \p = q \ word_of p = word_of q\ by (auto intro: word_of_eqI) end bundle constraintless begin declaration \ let val cs = map (rpair NONE o fst o dest_Const) [\<^term>\0\, \<^term>\(+)\, \<^term>\uminus\, \<^term>\(-)\, \<^term>\1\, \<^term>\(*)\, \<^term>\(div)\, \<^term>\(mod)\, \<^term>\HOL.equal\, \<^term>\(\)\, \<^term>\(<)\, \<^term>\(dvd)\, \<^term>\of_bool\, \<^term>\numeral\, \<^term>\of_nat\, \<^term>\bit\, \<^term>\NOT\, \<^term>\Bit_Operations.and\, \<^term>\Bit_Operations.or\, \<^term>\Bit_Operations.xor\, \<^term>\mask\, \<^term>\push_bit\, \<^term>\drop_bit\, \<^term>\take_bit\, \<^term>\Bit_Operations.set_bit\, \<^term>\unset_bit\, \<^term>\flip_bit\, \<^term>\msb\, \<^term>\lsb\, \<^term>\size\, \<^term>\Generic_set_bit.set_bit\, \<^term>\set_bits\] in K (Context.mapping I (fold Proof_Context.add_const_constraint cs)) end \ end locale word_type_copy_ring = word_type_copy opening constraintless + constrains word_of :: \'a \ 'b::len word\ assumes word_of_0 [code]: \word_of 0 = 0\ and word_of_1 [code]: \word_of 1 = 1\ and word_of_add [code]: \word_of (p + q) = word_of p + word_of q\ and word_of_minus [code]: \word_of (- p) = - (word_of p)\ and word_of_diff [code]: \word_of (p - q) = word_of p - word_of q\ and word_of_mult [code]: \word_of (p * q) = word_of p * word_of q\ and word_of_div [code]: \word_of (p div q) = word_of p div word_of q\ and word_of_mod [code]: \word_of (p mod q) = word_of p mod word_of q\ and equal_iff_word_of [code]: \HOL.equal p q \ HOL.equal (word_of p) (word_of q)\ and less_eq_iff_word_of [code]: \p \ q \ word_of p \ word_of q\ and less_iff_word_of [code]: \p < q \ word_of p < word_of q\ begin lemma of_class_comm_ring_1: \OFCLASS('a, comm_ring_1_class)\ by standard (simp_all add: eq_iff_word_of word_of_0 word_of_1 word_of_add word_of_minus word_of_diff word_of_mult algebra_simps) lemma of_class_semiring_modulo: \OFCLASS('a, semiring_modulo_class)\ by standard (simp_all add: eq_iff_word_of word_of_0 word_of_1 word_of_add word_of_minus word_of_diff word_of_mult word_of_mod word_of_div algebra_simps mod_mult_div_eq) lemma of_class_equal: \OFCLASS('a, equal_class)\ by standard (simp add: eq_iff_word_of equal_iff_word_of equal) lemma of_class_linorder: \OFCLASS('a, linorder_class)\ by standard (auto simp add: eq_iff_word_of less_eq_iff_word_of less_iff_word_of) end locale word_type_copy_bits = word_type_copy_ring opening constraintless bit_operations_syntax + constrains word_of :: \'a::{comm_ring_1, semiring_modulo, equal, linorder} \ 'b::len word\ fixes signed_drop_bit :: \nat \ 'a \ 'a\ assumes bit_eq_word_of [code]: \bit p = bit (word_of p)\ and word_of_not [code]: \word_of (NOT p) = NOT (word_of p)\ and word_of_and [code]: \word_of (p AND q) = word_of p AND word_of q\ and word_of_or [code]: \word_of (p OR q) = word_of p OR word_of q\ and word_of_xor [code]: \word_of (p XOR q) = word_of p XOR word_of q\ and word_of_mask [code]: \word_of (mask n) = mask n\ and word_of_push_bit [code]: \word_of (push_bit n p) = push_bit n (word_of p)\ and word_of_drop_bit [code]: \word_of (drop_bit n p) = drop_bit n (word_of p)\ and word_of_signed_drop_bit [code]: \word_of (signed_drop_bit n p) = Word.signed_drop_bit n (word_of p)\ and word_of_take_bit [code]: \word_of (take_bit n p) = take_bit n (word_of p)\ and word_of_set_bit [code]: \word_of (Bit_Operations.set_bit n p) = Bit_Operations.set_bit n (word_of p)\ and word_of_unset_bit [code]: \word_of (unset_bit n p) = unset_bit n (word_of p)\ and word_of_flip_bit [code]: \word_of (flip_bit n p) = flip_bit n (word_of p)\ begin lemma word_of_bool: \word_of (of_bool n) = of_bool n\ by (simp add: word_of_0 word_of_1) lemma word_of_nat: \word_of (of_nat n) = of_nat n\ by (induction n) (simp_all add: word_of_0 word_of_1 word_of_add) lemma word_of_numeral [simp]: \word_of (numeral n) = numeral n\ proof - have \word_of (of_nat (numeral n)) = of_nat (numeral n)\ by (simp only: word_of_nat) then show ?thesis by simp qed lemma word_of_power: \word_of (p ^ n) = word_of p ^ n\ by (induction n) (simp_all add: word_of_1 word_of_mult word_of_numeral) lemma even_iff_word_of: \2 dvd p \ 2 dvd word_of p\ (is \?P \ ?Q\) proof assume ?P then obtain q where \p = 2 * q\ .. then show ?Q by (simp add: word_of_mult word_of_numeral) next assume ?Q then obtain w where \word_of p = 2 * w\ .. then have \of_word (word_of p) = of_word (2 * w)\ by simp then have \p = 2 * of_word w\ by (simp add: eq_iff_word_of word_of_word word_of_mult word_of_numeral) then show ?P by simp qed lemma of_class_ring_bit_operations: \OFCLASS('a, ring_bit_operations_class)\ proof - have induct: \P p\ if stable: \(\p. p div 2 = p \ P p)\ and rec: \(\p b. P p \ (of_bool b + 2 * p) div 2 = p \ P (of_bool b + 2 * p))\ for p :: 'a and P proof - from stable have stable': \(\p. word_of p div 2 = word_of p \ P p)\ by (simp add: eq_iff_word_of word_of_div word_of_numeral) from rec have rec': \(\p b. P p \ (of_bool b + 2 * word_of p) div 2 = word_of p \ P (of_bool b + 2 * p))\ by (simp add: eq_iff_word_of word_of_add word_of_bool word_of_mult word_of_div word_of_numeral) define w where \w = word_of p\ then have \p = of_word w\ by (simp add: of_word_of) also have \P (of_word w)\ proof (induction w rule: bits_induct) case (stable w) show ?case by (rule stable') (simp add: word_of_word stable) next case (rec w b) have \P (of_bool b + 2 * of_word w)\ by (rule rec') (simp_all add: word_of_word rec) also have \of_bool b + 2 * of_word w = of_word (of_bool b + 2 * w)\ by (simp add: eq_iff_word_of word_of_word word_of_add word_of_1 word_of_mult word_of_numeral word_of_0) finally show ?case . qed finally show \P p\ . qed have \class.semiring_parity_axioms (+) (0::'a) (*) 1 (mod)\ by standard (simp_all add: eq_iff_word_of word_of_0 word_of_1 word_of_numeral even_iff_word_of word_of_mod even_iff_mod_2_eq_zero) with of_class_semiring_modulo have \OFCLASS('a, semiring_parity_class)\ by (rule semiring_parity_class.intro) moreover have \class.semiring_bits_axioms (+) (-) (0::'a) (*) 1 (div) (mod) bit\ apply (standard, fact induct) apply (simp_all only: eq_iff_word_of word_of_0 word_of_1 word_of_bool word_of_numeral word_of_add word_of_diff word_of_mult word_of_div word_of_mod word_of_power even_iff_word_of bit_eq_word_of push_bit_take_bit drop_bit_take_bit even_drop_bit_iff_not_bit flip: push_bit_eq_mult drop_bit_eq_div take_bit_eq_mod mask_eq_exp_minus_1) apply (auto simp add: ac_simps bit_simps drop_bit_exp_eq push_bit_of_1) done ultimately have \OFCLASS('a, semiring_bits_class)\ by (rule semiring_bits_class.intro) moreover have \class.semiring_bit_operations_axioms (+) (-) (*) (1::'a) (div) (mod) bit (AND) (OR) (XOR) mask Bit_Operations.set_bit unset_bit flip_bit push_bit drop_bit take_bit\ by standard (simp_all add: eq_iff_word_of word_of_push_bit word_of_power bit_eq_word_of word_of_and word_of_or word_of_xor word_of_mask word_of_diff word_of_1 bit_simps word_of_set_bit set_bit_eq_or word_of_unset_bit word_of_flip_bit flip_bit_eq_xor word_of_mult word_of_drop_bit word_of_div word_of_take_bit word_of_mod flip: mask_eq_exp_minus_1 push_bit_eq_mult drop_bit_eq_div take_bit_eq_mod) ultimately have \OFCLASS('a, semiring_bit_operations_class)\ by (rule semiring_bit_operations_class.intro) moreover have \OFCLASS('a, ring_parity_class)\ using \OFCLASS('a, semiring_parity_class)\ by (rule ring_parity_class.intro) standard moreover have \class.ring_bit_operations_axioms (+) (-) (0::'a) (*) 1 bit uminus NOT\ by standard (simp_all add: eq_iff_word_of word_of_power word_of_numeral - bit_eq_word_of word_of_diff word_of_1 bit_simps + bit_eq_word_of word_of_diff word_of_1 bit_simps linorder_not_le word_of_not word_of_0 word_of_minus minus_eq_not_minus_1) ultimately show \OFCLASS('a, ring_bit_operations_class)\ by (rule ring_bit_operations_class.intro) qed lemma [code]: \take_bit n a = a AND mask n\ for a :: 'a by (simp add: eq_iff_word_of word_of_take_bit word_of_and word_of_mask take_bit_eq_mask) lemma [code]: \mask (Suc n) = push_bit n (1 :: 'a) OR mask n\ \mask 0 = (0 :: 'a)\ by (simp_all add: eq_iff_word_of word_of_mask word_of_or word_of_push_bit word_of_0 word_of_1 mask_Suc_exp push_bit_of_1) lemma [code]: \Bit_Operations.set_bit n w = w OR push_bit n 1\ for w :: 'a by (simp add: eq_iff_word_of word_of_set_bit word_of_or word_of_push_bit word_of_1 set_bit_eq_or) lemma [code]: \unset_bit n w = w AND NOT (push_bit n 1)\ for w :: 'a by (simp add: eq_iff_word_of word_of_unset_bit word_of_and word_of_not word_of_push_bit word_of_1 unset_bit_eq_and_not) lemma [code]: \flip_bit n w = w XOR push_bit n 1\ for w :: 'a by (simp add: eq_iff_word_of word_of_flip_bit word_of_xor word_of_push_bit word_of_1 flip_bit_eq_xor) end locale word_type_copy_more = word_type_copy_bits + constrains word_of :: \'a::{ring_bit_operations, equal, linorder} \ 'b::len word\ fixes of_nat :: \nat \ 'a\ and nat_of :: \'a \ nat\ and of_int :: \int \ 'a\ and int_of :: \'a \ int\ and of_integer :: \integer \ 'a\ and integer_of :: \'a \ integer\ assumes word_of_nat_eq: \word_of (of_nat n) = word_of_nat n\ and nat_of_eq_word_of: \nat_of p = unat (word_of p)\ and word_of_int_eq: \word_of (of_int k) = word_of_int k\ and int_of_eq_word_of: \int_of p = uint (word_of p)\ and word_of_integer_eq: \word_of (of_integer l) = word_of_integer l\ and integer_of_eq_word_of: \integer_of p = unsigned (word_of p)\ begin lemma of_word_numeral [code_post]: \of_word (numeral n) = numeral n\ by (simp add: eq_iff_word_of word_of_word word_of_numeral) lemma of_word_0 [code_post]: \of_word 0 = 0\ by (simp add: eq_iff_word_of word_of_0 word_of_word) lemma of_word_1 [code_post]: \of_word 1 = 1\ by (simp add: eq_iff_word_of word_of_1 word_of_word) text \Use pretty numerals from integer for pretty printing\ lemma numeral_eq_integer [code_unfold]: \numeral n = of_integer (numeral n)\ by (simp add: eq_iff_word_of word_of_integer_eq word_of_numeral word_of_integer.rep_eq) lemma neg_numeral_eq_integer [code_unfold]: \- numeral n = of_integer (- numeral n)\ by (simp add: eq_iff_word_of word_of_integer_eq word_of_minus word_of_numeral word_of_integer.rep_eq) end locale word_type_copy_misc = word_type_copy_more opening constraintless bit_operations_syntax + constrains word_of :: \'a::{ring_bit_operations, equal, linorder} \ 'b::len word\ fixes size :: nat and set_bits_aux :: \(nat \ bool) \ nat \ 'a \ 'a\ assumes size_eq_length: \size = LENGTH('b::len)\ and msb_iff_word_of [code]: \msb p \ msb (word_of p)\ and lsb_iff_word_of [code]: \lsb p \ lsb (word_of p)\ and size_eq_word_of: \Nat.size (p :: 'a) = Nat.size (word_of p)\ and word_of_generic_set_bit [code]: \word_of (Generic_set_bit.set_bit p n b) = Generic_set_bit.set_bit (word_of p) n b\ and word_of_set_bits: \word_of (set_bits P) = set_bits P\ and word_of_set_bits_aux: \word_of (set_bits_aux P n p) = Code_Target_Word_Base.set_bits_aux P n (word_of p)\ begin lemma size_eq [code]: \Nat.size p = size\ for p :: 'a by (simp add: size_eq_length size_eq_word_of word_size) lemma set_bits_aux_code [code]: \set_bits_aux f n w = (if n = 0 then w else let n' = n - 1 in set_bits_aux f n' (push_bit 1 w OR (if f n' then 1 else 0)))\ by (simp add: eq_iff_word_of word_of_set_bits_aux Let_def word_of_mult word_of_or word_of_0 word_of_1 set_bits_aux_rec [of f n]) lemma set_bits_code [code]: \set_bits P = set_bits_aux P size 0\ by (simp add: fun_eq_iff eq_iff_word_of word_of_set_bits word_of_set_bits_aux word_of_0 size_eq_length set_bits_conv_set_bits_aux) lemma of_class_lsb: \OFCLASS('a, lsb_class)\ by standard (simp add: fun_eq_iff lsb_iff_word_of even_iff_word_of lsb_odd) lemma of_class_set_bit: \OFCLASS('a, set_bit_class)\ - by standard (simp add: eq_iff_word_of word_of_generic_set_bit bit_eq_word_of word_of_power word_of_numeral word_of_0 bit_simps) + by standard (simp add: eq_iff_word_of word_of_generic_set_bit bit_eq_word_of word_of_power word_of_0 bit_simps linorder_not_le) lemma of_class_bit_comprehension: \OFCLASS('a, bit_comprehension_class)\ by standard (simp add: eq_iff_word_of word_of_set_bits bit_eq_word_of set_bits_bit_eq) end end 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 @@ -1,1334 +1,1331 @@ (* * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230) * * SPDX-License-Identifier: BSD-2-Clause *) section "Word Alignment" theory Aligned imports "HOL-Library.Word" More_Word Word_EqI begin context includes bit_operations_syntax begin lift_definition is_aligned :: \'a::len word \ nat \ bool\ is \\k n. 2 ^ n dvd take_bit LENGTH('a) k\ by simp lemma is_aligned_iff_udvd: \is_aligned w n \ 2 ^ n udvd w\ by transfer (simp flip: take_bit_eq_0_iff add: min_def) lemma is_aligned_iff_take_bit_eq_0: \is_aligned w n \ take_bit n w = 0\ by (simp add: is_aligned_iff_udvd take_bit_eq_0_iff exp_dvd_iff_exp_udvd) lemma is_aligned_iff_dvd_int: \is_aligned ptr n \ 2 ^ n dvd uint ptr\ by transfer simp lemma is_aligned_iff_dvd_nat: \is_aligned ptr n \ 2 ^ n dvd unat ptr\ proof - have \unat ptr = nat \uint ptr\\ by transfer simp then have \2 ^ n dvd unat ptr \ 2 ^ n dvd uint ptr\ by (simp only: dvd_nat_abs_iff) simp then show ?thesis by (simp add: is_aligned_iff_dvd_int) qed lemma is_aligned_0 [simp]: \is_aligned 0 n\ by transfer simp lemma is_aligned_at_0 [simp]: \is_aligned w 0\ by transfer simp lemma is_aligned_beyond_length: \is_aligned w n \ w = 0\ if \LENGTH('a) \ n\ for w :: \'a::len word\ using that apply (simp add: is_aligned_iff_udvd) apply transfer apply auto done lemma is_alignedI [intro?]: \is_aligned x n\ if \x = 2 ^ n * k\ for x :: \'a::len word\ proof (unfold is_aligned_iff_udvd) from that show \2 ^ n udvd x\ using dvd_triv_left exp_dvd_iff_exp_udvd by blast qed lemma is_alignedE: fixes w :: \'a::len word\ assumes \is_aligned w n\ obtains q where \w = 2 ^ n * word_of_nat q\ \q < 2 ^ (LENGTH('a) - n)\ proof (cases \n < LENGTH('a)\) case False with assms have \w = 0\ by (simp add: is_aligned_beyond_length) with that [of 0] show thesis by simp next case True moreover define m where \m = LENGTH('a) - n\ ultimately have l: \LENGTH('a) = n + m\ and \m \ 0\ by simp_all from \n < LENGTH('a)\ have *: \unat (2 ^ n :: 'a word) = 2 ^ n\ by transfer simp from assms have \2 ^ n udvd w\ by (simp add: is_aligned_iff_udvd) then obtain v :: \'a word\ where \unat w = unat (2 ^ n :: 'a word) * unat v\ .. moreover define q where \q = unat v\ ultimately have unat_w: \unat w = 2 ^ n * q\ by (simp add: *) then have \word_of_nat (unat w) = (word_of_nat (2 ^ n * q) :: 'a word)\ by simp then have w: \w = 2 ^ n * word_of_nat q\ by simp moreover have \q < 2 ^ (LENGTH('a) - n)\ proof (rule ccontr) assume \\ q < 2 ^ (LENGTH('a) - n)\ then have \2 ^ (LENGTH('a) - n) \ q\ by simp then have \2 ^ LENGTH('a) \ 2 ^ n * q\ by (simp add: l power_add) with unat_w [symmetric] show False by (metis le_antisym nat_less_le unsigned_less) qed ultimately show thesis using that by blast qed lemma is_alignedE' [elim?]: fixes w :: \'a::len word\ assumes \is_aligned w n\ obtains q where \w = push_bit n (word_of_nat q)\ \q < 2 ^ (LENGTH('a) - n)\ proof - from assms obtain q where \w = 2 ^ n * word_of_nat q\ \q < 2 ^ (LENGTH('a) - n)\ by (rule is_alignedE) then have \w = push_bit n (word_of_nat q)\ by (simp add: push_bit_eq_mult) with that show thesis using \q < 2 ^ (LENGTH('a) - n)\ . qed lemma is_aligned_mask: \is_aligned w n \ w AND mask n = 0\ by (simp add: is_aligned_iff_take_bit_eq_0 take_bit_eq_mask) lemma is_aligned_imp_not_bit: \\ bit w m\ if \is_aligned w n\ and \m < n\ for w :: \'a::len word\ proof - from \is_aligned w n\ obtain q where \w = push_bit n (word_of_nat q)\ \q < 2 ^ (LENGTH('a) - n)\ .. moreover have \\ bit (push_bit n (word_of_nat q :: 'a word)) m\ using \m < n\ by (simp add: bit_simps) ultimately show ?thesis by simp qed lemma is_aligned_weaken: "\ is_aligned w x; x \ y \ \ is_aligned w y" unfolding is_aligned_iff_dvd_nat by (erule dvd_trans [rotated]) (simp add: le_imp_power_dvd) lemma is_alignedE_pre: fixes w::"'a::len word" assumes aligned: "is_aligned w n" shows rl: "\q. w = 2 ^ n * (of_nat q) \ q < 2 ^ (LENGTH('a) - n)" using aligned is_alignedE by blast lemma aligned_add_aligned: fixes x::"'a::len word" assumes aligned1: "is_aligned x n" and aligned2: "is_aligned y m" and lt: "m \ 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" using q1v unat_mult_power_lem xv by blast have "unat y = 2 ^ m * q2" using q2v unat_mult_power_lem yv by blast then show ?thesis using f1 by (simp add: power_add semiring_normalization_rules(34)) qed (* (2 ^ k * q1 + q2) *) show "\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 "\ = 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 "\ = (2 ^ m * (2 ^ k * q1 + q2)) mod 2 ^ LENGTH('a)" by (subst upls, rule refl) also have "\ = 2 ^ m * ((2 ^ k * q1 + q2) mod 2 ^ (LENGTH('a) - m))" proof - have "m \ 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 "\ 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: "\is_aligned (x::'a::len word) n; is_aligned y m; m \ n\ \ 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 (push_bit m k) 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 (push_bit m k)" 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 (push_bit m k) = unat (2 ^ m * k)" by (simp add: push_bit_eq_mult ac_simps) also have "\ = (2 ^ m * unat k) mod (2 ^ LENGTH('a))" using mv by (simp add: unat_word_ariths(2)) also have "\ = 2 ^ m * (unat k mod 2 ^ q)" by (subst mq [symmetric], subst power_add, subst mod_mult2_eq) simp finally show "unat (push_bit m k) = 2 ^ m * (unat k mod 2 ^ q)" . qed then show ?thesis by (unfold is_aligned_iff_dvd_nat) next assume "\ m < LENGTH('a)" then show ?thesis by (simp add: not_less power_overflow is_aligned_mask 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 "\ 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 \ x = 0" by simp 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 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 \ 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 \ p + (2 ^ n - 1)" proof cases assume "n n ptr \ ptr + 2^sz - 1" by (drule is_aligned_no_overflow') (simp add: field_simps) lemma replicate_not_True: "\n. xs = replicate n False \ True \ set xs" by (induct xs) auto lemma map_zip_replicate_False_xor: "n = length xs \ map (\(x, y). x = (\ y)) (zip xs (replicate n False)) = xs" by (induct xs arbitrary: n, auto) lemma drop_minus_lem: "\ n \ length xs; 0 < n; n' = length xs \ \ 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: "\ n < length xs; n' = length xs \ \ 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 aligned_add_xor: \(x + 2 ^ n) XOR 2 ^ n = x\ if al: \is_aligned (x::'a::len word) n'\ and le: \n < n'\ proof - have \\ bit x n\ using that by (rule is_aligned_imp_not_bit) then have \x + 2 ^ n = x OR 2 ^ n\ by (subst disjunctive_add) (auto simp add: bit_simps disjunctive_add) moreover have \(x OR 2 ^ n) XOR 2 ^ n = x\ by (rule bit_word_eqI) (auto simp add: bit_simps \\ bit x n\) ultimately show ?thesis by simp qed lemma is_aligned_add_mult_multI: fixes p :: "'a::len word" shows "\is_aligned p m; n \ m; n' = n\ \ 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 "\is_aligned p m; n \ m; n' = n\ \ is_aligned (p + x * 2 ^ n) n'" apply (erule aligned_add_aligned) apply (auto intro: is_alignedI [where k="x"]) done lemma is_aligned_no_wrap''': fixes ptr :: "'a::len word" shows"\ is_aligned ptr sz; sz < LENGTH('a); off < 2 ^ sz \ \ 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 "\ is_aligned p n; \ is_aligned p n; n < LENGTH('a) \ \ P; \ p = 0; n \ LENGTH('a) \ \ P \ \ 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: "\ is_aligned x n; x < 2 ^ n \ \ x = 0" by (simp add: is_aligned_mask less_mask_eq) corollary is_aligned_less_sz: "\is_aligned a sz; a \ 0\ \ \ a < 2 ^ sz" by (rule notI, drule(1) aligned_small_is_0, erule(1) notE) lemma aligned_at_least_t2n_diff: "\is_aligned x n; is_aligned y n; x < y\ \ x \ 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 is_aligned_no_overflow'': "\is_aligned x n; x + 2 ^ n \ 0\ \ x \ 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_bitI: \is_aligned p m\ if \\n. n < m \ \ bit p n\ apply (simp add: is_aligned_mask) apply (rule bit_word_eqI) using that apply (auto simp add: bit_simps) done lemma is_aligned_nth [word_eqI_simps]: "is_aligned p m = (\n < m. \ bit p n)" apply (auto intro: is_aligned_bitI simp add: is_aligned_mask bit_eq_iff) apply (auto simp: bit_simps) using bit_imp_le_length not_less apply blast done lemma range_inter: "({a..b} \ {c..d} = {}) = (\x. \(a \ x \ x \ b \ c \ x \ x \ d))" by auto lemma aligned_inter_non_empty: "\ {p..p + (2 ^ n - 1)} \ {p..p + 2 ^ m - 1} = {}; is_aligned p n; is_aligned p m\ \ 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: "\ is_aligned a n" shows "a mod 2 ^ n \ 0" apply (rule ccontr) using al apply (rule notE) apply simp apply (rule is_alignedI [of _ _ \a div 2 ^ n\]) apply (metis add.right_neutral mult.commute word_mod_div_equality) done lemma nat_add_offset_le: 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" by (auto simp: le_iff_add) have "x * 2 ^ n + y \ x * 2 ^ n + 2 ^ n" using yv xv by simp also have "\ = (x + 1) * 2 ^ n" by simp also have "\ \ 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_le: fixes ptr::"'a::len word" assumes al: "is_aligned ptr sz" and szv: "sz < LENGTH('a)" and off: "off \ 2 ^ sz" shows "unat ptr + off \ 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 \ 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 \ n \ is_aligned (x AND NOT (mask n)) m" by (rule is_aligned_bitI) (simp add: bit_simps) 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\ if \is_aligned p n\ for p :: \'a::len word\ using that apply (cases \n < LENGTH('a)\) 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: "\is_aligned (x :: 'a :: len word) n; \n' \ n. n' < LENGTH('a) \ \ bit p n'\ \ x + p AND NOT (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 add: bit_simps) apply (rule bit_word_eqI) apply (auto simp add: bit_simps not_less word_size) apply (metis is_aligned_nth not_le) done lemma is_aligned_andI1: "is_aligned x n \ is_aligned (x AND y) n" by (simp add: is_aligned_nth bit_simps) lemma is_aligned_andI2: "is_aligned y n \ is_aligned (x AND y) n" by (simp add: is_aligned_nth bit_simps) lemma is_aligned_shiftl: "is_aligned w (n - m) \ is_aligned (push_bit m w) n" by (simp add: is_aligned_nth bit_simps) lemma is_aligned_shiftr: "is_aligned w (n + m) \ is_aligned (drop_bit m w) n" by (simp add: is_aligned_nth bit_simps) lemma is_aligned_shiftl_self: "is_aligned (push_bit n p) n" by (rule is_aligned_shift) lemma is_aligned_neg_mask_eq: "is_aligned p n \ p AND NOT (mask n) = p" apply (rule bit_word_eqI) apply (auto simp add: bit_simps is_aligned_nth) done lemma is_aligned_shiftr_shiftl: "is_aligned w n \ push_bit n (drop_bit n w) = w" apply (rule bit_word_eqI) apply (auto simp add: bit_simps is_aligned_nth) using not_le_imp_less apply blast apply (metis add_diff_inverse_nat) done lemma aligned_shiftr_mask_shiftl: "is_aligned x n \ push_bit n (drop_bit n x AND mask v) = x AND mask (v + n)" apply (rule word_eqI) apply (simp add: word_size bit_simps) apply (subgoal_tac "\m. bit x m \ m \ 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 bit_simps) done lemma mask_zero: "is_aligned x a \ x AND mask a = 0" by (metis is_aligned_mask) lemma is_aligned_neg_mask_eq_concrete: "\ is_aligned p n; msk AND NOT (mask n) = NOT (mask n) \ \ p AND msk = p" by (metis word_bw_assocs(1) word_bw_comms(1) is_aligned_neg_mask_eq) lemma is_aligned_and_not_zero: "\ is_aligned n k; n \ 0 \ \ 2 ^ k \ n" using is_aligned_less_sz leI by blast lemma is_aligned_and_2_to_k: "(n AND 2 ^ k - 1) = 0 \ is_aligned (n :: 'a :: len word) k" by (simp add: is_aligned_mask mask_eq_decr_exp) lemma is_aligned_power2: "b \ a \ is_aligned (2 ^ a) b" by (metis is_aligned_triv is_aligned_weaken) lemma aligned_sub_aligned': "\ is_aligned (a :: 'a :: len word) n; is_aligned b n; n < LENGTH('a) \ \ is_aligned (a - b) n" by (simp add: aligned_sub_aligned) lemma is_aligned_neg_mask_weaken: "\ is_aligned p n; m \ n \ \ p AND NOT (mask m) = p" using is_aligned_neg_mask_eq is_aligned_weaken by blast lemma is_aligned_neg_mask2 [simp]: "is_aligned (a AND NOT (mask n)) n" by (rule is_aligned_bitI) (simp add: bit_simps) lemma is_aligned_0': "is_aligned 0 n" by (fact is_aligned_0) 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 "\ 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 (simp flip: take_bit_eq_mod) apply (rule bit_word_eqI) apply (auto simp add: bit_simps) apply (metis assms(2) bit_or_iff is_aligned_mask is_aligned_nth leD less_mask_eq word_and_le1 word_bw_lcs(1) word_neq_0_conv word_plus_and_or_coroll) apply (meson assms(2) leI less_2p_is_upper_bits_unset) apply (metis assms(2) bit_disjunctive_add_iff bit_imp_le_length bit_push_bit_iff is_alignedE' less_2p_is_upper_bits_unset) done next assume "\ 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 aligned_neq_into_no_overlap: fixes x :: "'a::len word" assumes neq: "x \ y" and alx: "is_aligned x sz" and aly: "is_aligned y sz" shows "{x .. x + (2 ^ sz - 1)} \ {y .. y + (2 ^ sz - 1)} = {}" proof cases assume szv: "sz < LENGTH('a)" show ?thesis proof (rule equals0I, clarsimp) fix z assume xb: "x \ z" and xt: "z \ x + (2 ^ sz - 1)" and yb: "y \ z" and yt: "z \ y + (2 ^ sz - 1)" have rl: "\(p::'a word) k w. \uint p + uint k < 2 ^ LENGTH('a); w = p + k; w \ p + (2 ^ sz - 1) \ \ 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 transfer apply simp apply (auto simp add: le_less power_2_ge_iff szv) apply (metis le_less_trans mask_eq_decr_exp mask_lt_2pn order_less_imp_le 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 "\ = 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 "\ 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 is_aligned_add_helper: "\ is_aligned p n; d < 2 ^ n \ \ (p + d AND mask n = d) \ (p + d AND (NOT (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) apply (simp_all flip: take_bit_eq_mask) apply (metis take_bit_eq_mask word_bw_lcs(1) word_log_esimps(1)) apply (metis add.commute add_left_imp_eq take_bit_eq_mask word_plus_and_or_coroll2) done lemmas mask_inner_mask = mask_eqs(1) lemma mask_add_aligned: "is_aligned p n \ (p + q) AND mask n = q AND mask n" apply (simp add: is_aligned_mask) apply (subst mask_inner_mask [symmetric]) apply simp done lemma mask_out_add_aligned: assumes al: "is_aligned p n" shows "p + (q AND NOT (mask n)) = (p + q) AND NOT (mask n)" using mask_add_aligned [OF al] by (simp add: mask_out_sub_mask) lemma is_aligned_add_or: "\is_aligned p n; d < 2 ^ n\ \ p + d = p OR d" - apply (subst disjunctive_add) - apply (simp_all add: is_aligned_iff_take_bit_eq_0) - apply (simp add: bit_eq_iff) - apply (auto simp add: bit_simps) + apply (subst disjunctive_add, simp_all) + apply (clarsimp simp: is_aligned_nth less_2p_is_upper_bits_unset) subgoal for m apply (cases \m < n\) - apply (auto simp add: not_less) - apply (metis bit_take_bit_iff less_mask_eq take_bit_eq_mask) + apply (auto simp add: not_less dest: bit_imp_possible_bit) done done lemma not_greatest_aligned: "\ x < y; is_aligned x n; is_aligned y n \ \ x + 2 ^ n \ 0" by (metis NOT_mask add_diff_cancel_right' diff_0 is_aligned_neg_mask_eq not_le word_and_le1) lemma neg_mask_mono_le: "x \ y \ x AND NOT(mask n) \ y AND NOT(mask n)" for x :: "'a :: len word" proof (rule ccontr, simp add: linorder_not_le, cases "n < LENGTH('a)") case False then show "y AND NOT(mask n) < x AND NOT(mask n) \ False" by (simp add: mask_eq_decr_exp linorder_not_less power_overflow) next case True assume a: "x \ y" and b: "y AND NOT(mask n) < x AND NOT(mask n)" have word_bits: "n < LENGTH('a)" by fact have "y \ (y AND NOT(mask n)) + (y AND mask n)" by (simp add: word_plus_and_or_coroll2 add.commute) also have "\ \ (y AND NOT(mask n)) + 2 ^ n" apply (rule word_plus_mono_right) apply (rule order_less_imp_le, rule and_mask_less_size) apply (simp add: word_size word_bits) apply (rule is_aligned_no_overflow'', simp add: is_aligned_neg_mask word_bits) apply (rule not_greatest_aligned, rule b; simp add: is_aligned_neg_mask) done also have "\ \ x AND NOT(mask n)" using b apply (subst add.commute) apply (rule le_plus) apply (rule aligned_at_least_t2n_diff; simp add: is_aligned_neg_mask) apply (rule ccontr, simp add: linorder_not_le) apply (drule aligned_small_is_0[rotated]; simp add: is_aligned_neg_mask) done also have "\ \ x" by (rule word_and_le2) also have "x \ y" by fact finally show "False" using b by simp qed lemma and_neg_mask_eq_iff_not_mask_le: "w AND NOT(mask n) = NOT(mask n) \ NOT(mask n) \ w" for w :: \'a::len word\ by (metis eq_iff neg_mask_mono_le word_and_le1 word_and_le2 word_bw_same(1)) lemma neg_mask_le_high_bits [word_eqI_simps]: \NOT (mask n) \ w \ (\i \ {n ..< size w}. bit w i)\ (is \?P \ ?Q\) for w :: \'a::len word\ proof assume ?Q then have \w AND NOT (mask n) = NOT (mask n)\ by (auto simp add: bit_simps word_size intro: bit_word_eqI) then show ?P by (simp add: and_neg_mask_eq_iff_not_mask_le) next assume ?P then have *: \w AND NOT (mask n) = NOT (mask n)\ by (simp add: and_neg_mask_eq_iff_not_mask_le) show \?Q\ proof (rule ccontr) assume \\ (\i\{n.. then obtain m where m: \\ bit w m\ \n \ m\ \m < LENGTH('a)\ by (auto simp add: word_size) from * have \bit (w AND NOT (mask n)) m \ bit (NOT (mask n :: 'a word)) m\ by auto with m show False by (auto simp add: bit_simps) qed qed lemma is_aligned_add_less_t2n: "\is_aligned (p::'a::len word) n; d < 2^n; n \ m; p < 2^m\ \ 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: "\ is_aligned x n; y < 2 ^ n; x \ 0 \ \ x + y \ 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 lemma is_aligned_over_length: "\ is_aligned p n; LENGTH('a) \ n \ \ (p::'a::len word) = 0" by (simp add: is_aligned_mask mask_over_length) lemma is_aligned_no_overflow_mask: "is_aligned x n \ x \ x + mask n" by (simp add: mask_eq_decr_exp) (erule is_aligned_no_overflow') lemma aligned_mask_step: "\ n' \ n; p' \ p + mask n; is_aligned p n; is_aligned p' n' \ \ (p'::'a::len word) + mask n' \ p + mask n" apply (cases "LENGTH('a) \ 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: dvd_def is_aligned_iff_dvd_nat) 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 is_aligned_mask_offset_unat: fixes off :: "('a::len) word" and x :: "'a word" assumes al: "is_aligned x sz" and offv: "off \ 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 "\ sz < LENGTH('a)" with al have "x = 0" by (meson is_aligned_get_word_bits) thus ?thesis by simp qed lemma aligned_less_plus_1: "\ is_aligned x n; n > 0 \ \ x < x + 1" apply (rule plus_one_helper2) apply (rule order_refl) apply (clarsimp simp: field_simps) apply (drule arg_cong[where f="\x. x - 1"]) apply (clarsimp simp: is_aligned_mask) apply (drule word_eqD[where x=0]) apply (simp add: even_mask_iff) done lemma aligned_add_offset_less: "\is_aligned x n; is_aligned y n; x < y; z < 2 ^ n\ \ 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 gap_between_aligned: "\a < (b :: 'a ::len word); is_aligned a n; is_aligned b n; n < LENGTH('a) \ \ a + (2^n - 1) < b" by (simp add: aligned_add_offset_less) lemma is_aligned_add_step_le: "\ is_aligned (a::'a::len word) n; is_aligned b n; a < b; b \ a + mask n \ \ False" apply (simp flip: not_le) apply (erule notE) apply (cases "LENGTH('a) \ n") apply (drule (1) is_aligned_over_length)+ apply (drule mask_over_length) apply clarsimp apply (clarsimp simp: word_le_nat_alt not_less not_le) apply (subst (asm) unat_plus_simple[THEN iffD1], erule is_aligned_no_overflow_mask) apply (subst (asm) unat_add_lem' [symmetric]) apply (simp add: is_aligned_mask_offset_unat) apply (metis gap_between_aligned linorder_not_less mask_eq_decr_exp unat_arith_simps(2)) done lemma aligned_add_mask_lessD: "\ x + mask n < y; is_aligned x n \ \ 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: "\ is_aligned x n; is_aligned y n; n < LENGTH('a) \ \ (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 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 \ {n .. n + (2 ^ s2 - 1)}" and s1s2: "s1 \ s2" and s10: "0 < s1" (* Probably can be folded into the proof \ *) shows "\q. m - n = of_nat q * 2 ^ s1 \ q < 2 ^ (s2 - s1)" proof - have rl: "\m s. \ m < 2 ^ (LENGTH('a) - s); s < LENGTH('a) \ \ 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 \ m" by clarsimp then have "(2::'a word) ^ s2 * of_nat nq \ 2 ^ s1 * of_nat mq" using nnq mmq by simp then have "2 ^ s2 * nq \ 2 ^ s1 * mq" using s1wb s2wb by (simp add: word_le_nat_alt us1 us2) then have nqmq: "2 ^ sq * nq \ 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 "\ = 2 ^ s1 * of_nat mq - 2 ^ s1 * 2 ^ sq * of_nat nq" using sq by (simp add: power_add) also have "\ = 2 ^ s1 * (of_nat mq - 2 ^ sq * of_nat nq)" by (simp add: field_simps) also have "\ = 2 ^ s1 * of_nat (mq - 2 ^ sq * nq)" using s1wb s2wb us1 us2 nqmq by (simp add: of_nat_diff) finally have mn: "m - n = of_nat (mq - 2 ^ sq * nq) * 2 ^ s1" by simp moreover from nm have "m - n \ 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 \LENGTH('a)\ \mq - 2 ^ sq * nq\] 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 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: "\is_aligned p n; is_aligned q n\ \ is_aligned (p + q) n" by (simp add: is_aligned_mask mask_add_aligned) lemma aligned_shift: "\x < 2 ^ n; is_aligned (y :: 'a :: len word) n;n \ LENGTH('a)\ \ drop_bit n (x + y) = drop_bit n y" apply (subst word_plus_and_or_coroll; rule bit_word_eqI) apply (auto simp add: bit_simps is_aligned_nth) apply (metis less_2p_is_upper_bits_unset not_le) apply (metis le_add1 less_2p_is_upper_bits_unset test_bit_bin) done lemma aligned_shift': "\x < 2 ^ n; is_aligned (y :: 'a :: len word) n;n \ LENGTH('a)\ \ drop_bit n (y + x) = drop_bit n y" apply (subst word_plus_and_or_coroll; rule bit_word_eqI) apply (auto simp add: bit_simps is_aligned_nth) apply (metis less_2p_is_upper_bits_unset not_le) apply (metis bit_imp_le_length le_add1 less_2p_is_upper_bits_unset) done lemma and_neg_mask_plus_mask_mono: "(p AND NOT (mask n)) + mask n \ p" for p :: \'a::len word\ apply (rule word_le_minus_cancel[where x = "p AND NOT (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 \ (ptr AND NOT (mask n)) + (2 ^ n - 1)" for ptr :: \'a::len word\ by (simp add: and_neg_mask_plus_mask_mono mask_2pm1[symmetric]) lemma is_aligned_sub_helper: "\ is_aligned (p - d) n; d < 2 ^ n \ \ (p AND mask n = d) \ (p AND (NOT (mask n)) = p - d)" by (drule(1) is_aligned_add_helper, simp) lemma is_aligned_after_mask: "\is_aligned k m;m\ n\ \ is_aligned (k AND mask n) m" by (rule is_aligned_andI1) lemma and_mask_plus: "\is_aligned ptr m; m \ n; a < 2 ^ m\ \ ptr + a AND mask n = (ptr AND 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 AND mask n) AND NOT (mask m) = (ptr + a AND NOT (mask m) ) AND 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 is_aligned_add_not_aligned: "\is_aligned (p::'a::len word) n; \ is_aligned (q::'a::len word) n\ \ \ is_aligned (p + q) n" by (metis is_aligned_addD1) lemma neg_mask_add_aligned: "\ is_aligned p n; q < 2 ^ n \ \ (p + q) AND NOT (mask n) = p AND NOT (mask n)" by (metis is_aligned_add_helper is_aligned_neg_mask_eq) 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 \ k" by (rule inc_le) then have "(a + 1) * 2 ^ m \ 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 "\ \ 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 (meson nat_mult_power_less_eq zero_less_numeral) done finally show ?thesis . qed lemma offset_not_aligned: "\ is_aligned (p::'a::len word) n; i > 0; i < 2 ^ n; n < LENGTH('a)\ \ \ is_aligned (p + of_nat i) n" apply (erule is_aligned_add_not_aligned) apply transfer apply (auto simp add: is_aligned_iff_udvd) apply (metis (no_types, lifting) le_less_trans less_not_refl2 less_or_eq_imp_le of_nat_eq_0_iff take_bit_eq_0_iff take_bit_nat_eq_self_iff take_bit_of_nat unat_lt2p unat_power_lower) done lemma le_or_mask: "w \ w' \ w OR mask x \ w' OR mask x" for w w' :: \'a::len word\ by (metis neg_mask_add_mask add.commute le_word_or1 mask_2pm1 neg_mask_mono_le word_plus_mono_left) end end diff --git a/thys/Word_Lib/Bits_Int.thy b/thys/Word_Lib/Bits_Int.thy --- a/thys/Word_Lib/Bits_Int.thy +++ b/thys/Word_Lib/Bits_Int.thy @@ -1,1573 +1,1573 @@ (* * Copyright Brian Huffman, PSU; Jeremy Dawson and Gerwin Klein, NICTA * * SPDX-License-Identifier: BSD-2-Clause *) section \Bitwise Operations on integers\ theory Bits_Int imports "Word_Lib.Most_significant_bit" "Word_Lib.Least_significant_bit" "Word_Lib.Generic_set_bit" "Word_Lib.Bit_Comprehension" begin subsection \Implicit bit representation of \<^typ>\int\\ lemma bin_last_def: "(odd :: int \ bool) w \ w mod 2 = 1" by (fact odd_iff_mod_2_eq_one) lemma bin_last_numeral_simps [simp]: "\ odd (0 :: int)" "odd (1 :: int)" "odd (- 1 :: int)" "odd (Numeral1 :: int)" "\ odd (numeral (Num.Bit0 w) :: int)" "odd (numeral (Num.Bit1 w) :: int)" "\ odd (- numeral (Num.Bit0 w) :: int)" "odd (- numeral (Num.Bit1 w) :: int)" by simp_all lemma bin_rest_numeral_simps [simp]: "(\k::int. k div 2) 0 = 0" "(\k::int. k div 2) 1 = 0" "(\k::int. k div 2) (- 1) = - 1" "(\k::int. k div 2) Numeral1 = 0" "(\k::int. k div 2) (numeral (Num.Bit0 w)) = numeral w" "(\k::int. k div 2) (numeral (Num.Bit1 w)) = numeral w" "(\k::int. k div 2) (- numeral (Num.Bit0 w)) = - numeral w" "(\k::int. k div 2) (- numeral (Num.Bit1 w)) = - numeral (w + Num.One)" by simp_all lemma bin_rl_eqI: "\(\k::int. k div 2) x = (\k::int. k div 2) y; odd x = odd y\ \ x = y" by (auto elim: oddE) lemma [simp]: shows bin_rest_lt0: "(\k::int. k div 2) i < 0 \ i < 0" and bin_rest_ge_0: "(\k::int. k div 2) i \ 0 \ i \ 0" by auto lemma bin_rest_gt_0 [simp]: "(\k::int. k div 2) x > 0 \ x > 1" by auto subsection \Bit projection\ lemma bin_nth_eq_iff: "(bit :: int \ nat \ bool) x = (bit :: int \ nat \ bool) y \ x = y" by (simp add: bit_eq_iff fun_eq_iff) lemma bin_eqI: "x = y" if "\n. (bit :: int \ nat \ bool) x n \ (bit :: int \ nat \ bool) y n" using that by (rule bit_eqI) lemma bin_eq_iff: "x = y \ (\n. (bit :: int \ nat \ bool) x n = (bit :: int \ nat \ bool) y n)" - by (fact bit_eq_iff) + by (metis bit_eq_iff) lemma bin_nth_zero [simp]: "\ (bit :: int \ nat \ bool) 0 n" by simp lemma bin_nth_1 [simp]: "(bit :: int \ nat \ bool) 1 n \ n = 0" by (cases n) (simp_all add: bit_Suc) lemma bin_nth_minus1 [simp]: "(bit :: int \ nat \ bool) (- 1) n" by simp lemma bin_nth_numeral: "(\k::int. k div 2) x = y \ (bit :: int \ nat \ bool) x (numeral n) = (bit :: int \ nat \ bool) y (pred_numeral n)" by (simp add: numeral_eq_Suc bit_Suc) lemmas bin_nth_numeral_simps [simp] = bin_nth_numeral [OF bin_rest_numeral_simps(8)] lemmas bin_nth_simps = bit_0 bit_Suc bin_nth_zero bin_nth_minus1 bin_nth_numeral_simps lemma nth_2p_bin: "(bit :: int \ nat \ bool) (2 ^ n) m = (m = n)" \ \for use when simplifying with \bin_nth_Bit\\ by (auto simp add: bit_exp_iff) lemma nth_rest_power_bin: "(bit :: int \ nat \ bool) (((\k::int. k div 2) ^^ k) w) n = (bit :: int \ nat \ bool) w (n + k)" apply (induct k arbitrary: n) apply clarsimp apply clarsimp apply (simp only: bit_Suc [symmetric] add_Suc) done lemma bin_nth_numeral_unfold: "(bit :: int \ nat \ bool) (numeral (num.Bit0 x)) n \ n > 0 \ (bit :: int \ nat \ bool) (numeral x) (n - 1)" "(bit :: int \ nat \ bool) (numeral (num.Bit1 x)) n \ (n > 0 \ (bit :: int \ nat \ bool) (numeral x) (n - 1))" by (cases n; simp)+ subsection \Truncating\ definition bin_sign :: "int \ int" where "bin_sign k = (if k \ 0 then 0 else - 1)" lemma bin_sign_simps [simp]: "bin_sign 0 = 0" "bin_sign 1 = 0" "bin_sign (- 1) = - 1" "bin_sign (numeral k) = 0" "bin_sign (- numeral k) = -1" by (simp_all add: bin_sign_def) lemma bin_sign_rest [simp]: "bin_sign ((\k::int. k div 2) w) = bin_sign w" by (simp add: bin_sign_def) lemma bintrunc_mod2p: "(take_bit :: nat \ int \ int) n w = w mod 2 ^ n" by (fact take_bit_eq_mod) lemma sbintrunc_mod2p: "(signed_take_bit :: nat \ int \ int) n w = (w + 2 ^ n) mod 2 ^ Suc n - 2 ^ n" by (simp add: bintrunc_mod2p signed_take_bit_eq_take_bit_shift) lemma sbintrunc_eq_take_bit: \(signed_take_bit :: nat \ int \ int) n k = take_bit (Suc n) (k + 2 ^ n) - 2 ^ n\ by (fact signed_take_bit_eq_take_bit_shift) lemma sign_bintr: "bin_sign ((take_bit :: nat \ int \ int) n w) = 0" by (simp add: bin_sign_def) lemma bintrunc_n_0: "(take_bit :: nat \ int \ int) n 0 = 0" by (fact take_bit_of_0) lemma sbintrunc_n_0: "(signed_take_bit :: nat \ int \ int) n 0 = 0" by (fact signed_take_bit_of_0) lemma sbintrunc_n_minus1: "(signed_take_bit :: nat \ int \ int) n (- 1) = -1" by (fact signed_take_bit_of_minus_1) lemma bintrunc_Suc_numeral: "(take_bit :: nat \ int \ int) (Suc n) 1 = 1" "(take_bit :: nat \ int \ int) (Suc n) (- 1) = 1 + 2 * (take_bit :: nat \ int \ int) n (- 1)" "(take_bit :: nat \ int \ int) (Suc n) (numeral (Num.Bit0 w)) = 2 * (take_bit :: nat \ int \ int) n (numeral w)" "(take_bit :: nat \ int \ int) (Suc n) (numeral (Num.Bit1 w)) = 1 + 2 * (take_bit :: nat \ int \ int) n (numeral w)" "(take_bit :: nat \ int \ int) (Suc n) (- numeral (Num.Bit0 w)) = 2 * (take_bit :: nat \ int \ int) n (- numeral w)" "(take_bit :: nat \ int \ int) (Suc n) (- numeral (Num.Bit1 w)) = 1 + 2 * (take_bit :: nat \ int \ int) n (- numeral (w + Num.One))" by (simp_all add: take_bit_Suc) lemma sbintrunc_0_numeral [simp]: "(signed_take_bit :: nat \ int \ int) 0 1 = -1" "(signed_take_bit :: nat \ int \ int) 0 (numeral (Num.Bit0 w)) = 0" "(signed_take_bit :: nat \ int \ int) 0 (numeral (Num.Bit1 w)) = -1" "(signed_take_bit :: nat \ int \ int) 0 (- numeral (Num.Bit0 w)) = 0" "(signed_take_bit :: nat \ int \ int) 0 (- numeral (Num.Bit1 w)) = -1" by simp_all lemma sbintrunc_Suc_numeral: "(signed_take_bit :: nat \ int \ int) (Suc n) 1 = 1" "(signed_take_bit :: nat \ int \ int) (Suc n) (numeral (Num.Bit0 w)) = 2 * (signed_take_bit :: nat \ int \ int) n (numeral w)" "(signed_take_bit :: nat \ int \ int) (Suc n) (numeral (Num.Bit1 w)) = 1 + 2 * (signed_take_bit :: nat \ int \ int) n (numeral w)" "(signed_take_bit :: nat \ int \ int) (Suc n) (- numeral (Num.Bit0 w)) = 2 * (signed_take_bit :: nat \ int \ int) n (- numeral w)" "(signed_take_bit :: nat \ int \ int) (Suc n) (- numeral (Num.Bit1 w)) = 1 + 2 * (signed_take_bit :: nat \ int \ int) n (- numeral (w + Num.One))" by (simp_all add: signed_take_bit_Suc) lemma bin_sign_lem: "(bin_sign ((signed_take_bit :: nat \ int \ int) n bin) = -1) = bit bin n" by (simp add: bin_sign_def) lemma nth_bintr: "(bit :: int \ nat \ bool) ((take_bit :: nat \ int \ int) m w) n \ n < m \ (bit :: int \ nat \ bool) w n" by (fact bit_take_bit_iff) lemma nth_sbintr: "(bit :: int \ nat \ bool) ((signed_take_bit :: nat \ int \ int) m w) n = (if n < m then (bit :: int \ nat \ bool) w n else (bit :: int \ nat \ bool) w m)" by (simp add: bit_signed_take_bit_iff min_def) lemma bin_nth_Bit0: "(bit :: int \ nat \ bool) (numeral (Num.Bit0 w)) n \ (\m. n = Suc m \ (bit :: int \ nat \ bool) (numeral w) m)" using bit_double_iff [of \numeral w :: int\ n] by (auto intro: exI [of _ \n - 1\]) lemma bin_nth_Bit1: "(bit :: int \ nat \ bool) (numeral (Num.Bit1 w)) n \ n = 0 \ (\m. n = Suc m \ (bit :: int \ nat \ bool) (numeral w) m)" using even_bit_succ_iff [of \2 * numeral w :: int\ n] bit_double_iff [of \numeral w :: int\ n] by auto lemma bintrunc_bintrunc_l: "n \ m \ (take_bit :: nat \ int \ int) m ((take_bit :: nat \ int \ int) n w) = (take_bit :: nat \ int \ int) n w" by (simp add: min.absorb2) lemma sbintrunc_sbintrunc_l: "n \ m \ (signed_take_bit :: nat \ int \ int) m ((signed_take_bit :: nat \ int \ int) n w) = (signed_take_bit :: nat \ int \ int) n w" by (simp add: min.absorb2) lemma bintrunc_bintrunc_ge: "n \ m \ (take_bit :: nat \ int \ int) n ((take_bit :: nat \ int \ int) m w) = (take_bit :: nat \ int \ int) n w" by (rule bin_eqI) (auto simp: nth_bintr) lemma bintrunc_bintrunc_min [simp]: "(take_bit :: nat \ int \ int) m ((take_bit :: nat \ int \ int) n w) = (take_bit :: nat \ int \ int) (min m n) w" by (rule take_bit_take_bit) lemma sbintrunc_sbintrunc_min [simp]: "(signed_take_bit :: nat \ int \ int) m ((signed_take_bit :: nat \ int \ int) n w) = (signed_take_bit :: nat \ int \ int) (min m n) w" by (rule signed_take_bit_signed_take_bit) lemmas sbintrunc_Suc_Pls = signed_take_bit_Suc [where a="0::int", simplified bin_last_numeral_simps bin_rest_numeral_simps] lemmas sbintrunc_Suc_Min = signed_take_bit_Suc [where a="-1::int", simplified bin_last_numeral_simps bin_rest_numeral_simps] lemmas sbintrunc_Sucs = sbintrunc_Suc_Pls sbintrunc_Suc_Min sbintrunc_Suc_numeral lemmas sbintrunc_Pls = signed_take_bit_0 [where a="0::int", simplified bin_last_numeral_simps bin_rest_numeral_simps] lemmas sbintrunc_Min = signed_take_bit_0 [where a="-1::int", simplified bin_last_numeral_simps bin_rest_numeral_simps] lemmas sbintrunc_0_simps = sbintrunc_Pls sbintrunc_Min lemmas sbintrunc_simps = sbintrunc_0_simps sbintrunc_Sucs lemma bintrunc_minus: "0 < n \ (take_bit :: nat \ int \ int) (Suc (n - 1)) w = (take_bit :: nat \ int \ int) n w" by auto lemma sbintrunc_minus: "0 < n \ (signed_take_bit :: nat \ int \ int) (Suc (n - 1)) w = (signed_take_bit :: nat \ int \ int) n w" by auto lemmas sbintrunc_minus_simps = sbintrunc_Sucs [THEN [2] sbintrunc_minus [symmetric, THEN trans]] lemma sbintrunc_BIT_I: \0 < n \ (signed_take_bit :: nat \ int \ int) (n - 1) 0 = y \ (signed_take_bit :: nat \ int \ int) n 0 = 2 * y\ by simp lemma sbintrunc_Suc_Is: \(signed_take_bit :: nat \ int \ int) n (- 1) = y \ (signed_take_bit :: nat \ int \ int) (Suc n) (- 1) = 1 + 2 * y\ by auto lemma sbintrunc_Suc_lem: "(signed_take_bit :: nat \ int \ int) (Suc n) x = y \ m = Suc n \ (signed_take_bit :: nat \ int \ int) m x = y" by (rule ssubst) lemmas sbintrunc_Suc_Ialts = sbintrunc_Suc_Is [THEN sbintrunc_Suc_lem] lemma sbintrunc_bintrunc_lt: "m > n \ (signed_take_bit :: nat \ int \ int) n ((take_bit :: nat \ int \ int) m w) = (signed_take_bit :: nat \ int \ int) n w" by (rule bin_eqI) (auto simp: nth_sbintr nth_bintr) lemma bintrunc_sbintrunc_le: "m \ Suc n \ (take_bit :: nat \ int \ int) m ((signed_take_bit :: nat \ int \ int) n w) = (take_bit :: nat \ int \ int) m w" by (rule take_bit_signed_take_bit) lemmas bintrunc_sbintrunc [simp] = order_refl [THEN bintrunc_sbintrunc_le] lemmas sbintrunc_bintrunc [simp] = lessI [THEN sbintrunc_bintrunc_lt] lemmas bintrunc_bintrunc [simp] = order_refl [THEN bintrunc_bintrunc_l] lemmas sbintrunc_sbintrunc [simp] = order_refl [THEN sbintrunc_sbintrunc_l] lemma bintrunc_sbintrunc' [simp]: "0 < n \ (take_bit :: nat \ int \ int) n ((signed_take_bit :: nat \ int \ int) (n - 1) w) = (take_bit :: nat \ int \ int) n w" by (cases n) simp_all lemma sbintrunc_bintrunc' [simp]: "0 < n \ (signed_take_bit :: nat \ int \ int) (n - 1) ((take_bit :: nat \ int \ int) n w) = (signed_take_bit :: nat \ int \ int) (n - 1) w" by (cases n) simp_all lemma bin_sbin_eq_iff: "(take_bit :: nat \ int \ int) (Suc n) x = (take_bit :: nat \ int \ int) (Suc n) y \ (signed_take_bit :: nat \ int \ int) n x = (signed_take_bit :: nat \ int \ int) n y" apply (rule iffI) apply (rule box_equals [OF _ sbintrunc_bintrunc sbintrunc_bintrunc]) apply simp apply (rule box_equals [OF _ bintrunc_sbintrunc bintrunc_sbintrunc]) apply simp done lemma bin_sbin_eq_iff': "0 < n \ (take_bit :: nat \ int \ int) n x = (take_bit :: nat \ int \ int) n y \ (signed_take_bit :: nat \ int \ int) (n - 1) x = (signed_take_bit :: nat \ int \ int) (n - 1) y" by (cases n) (simp_all add: bin_sbin_eq_iff) lemmas bintrunc_sbintruncS0 [simp] = bintrunc_sbintrunc' [unfolded One_nat_def] lemmas sbintrunc_bintruncS0 [simp] = sbintrunc_bintrunc' [unfolded One_nat_def] lemmas bintrunc_bintrunc_l' = le_add1 [THEN bintrunc_bintrunc_l] lemmas sbintrunc_sbintrunc_l' = le_add1 [THEN sbintrunc_sbintrunc_l] (* although bintrunc_minus_simps, if added to default simpset, tends to get applied where it's not wanted in developing the theories, we get a version for when the word length is given literally *) lemmas nat_non0_gr = trans [OF iszero_def [THEN Not_eq_iff [THEN iffD2]] refl] lemma bintrunc_numeral: "(take_bit :: nat \ int \ int) (numeral k) x = of_bool (odd x) + 2 * (take_bit :: nat \ int \ int) (pred_numeral k) (x div 2)" by (simp add: numeral_eq_Suc take_bit_Suc mod_2_eq_odd) lemma sbintrunc_numeral: "(signed_take_bit :: nat \ int \ int) (numeral k) x = of_bool (odd x) + 2 * (signed_take_bit :: nat \ int \ int) (pred_numeral k) (x div 2)" by (simp add: numeral_eq_Suc signed_take_bit_Suc mod2_eq_if) lemma bintrunc_numeral_simps [simp]: "(take_bit :: nat \ int \ int) (numeral k) (numeral (Num.Bit0 w)) = 2 * (take_bit :: nat \ int \ int) (pred_numeral k) (numeral w)" "(take_bit :: nat \ int \ int) (numeral k) (numeral (Num.Bit1 w)) = 1 + 2 * (take_bit :: nat \ int \ int) (pred_numeral k) (numeral w)" "(take_bit :: nat \ int \ int) (numeral k) (- numeral (Num.Bit0 w)) = 2 * (take_bit :: nat \ int \ int) (pred_numeral k) (- numeral w)" "(take_bit :: nat \ int \ int) (numeral k) (- numeral (Num.Bit1 w)) = 1 + 2 * (take_bit :: nat \ int \ int) (pred_numeral k) (- numeral (w + Num.One))" "(take_bit :: nat \ int \ int) (numeral k) 1 = 1" by (simp_all add: bintrunc_numeral) lemma sbintrunc_numeral_simps [simp]: "(signed_take_bit :: nat \ int \ int) (numeral k) (numeral (Num.Bit0 w)) = 2 * (signed_take_bit :: nat \ int \ int) (pred_numeral k) (numeral w)" "(signed_take_bit :: nat \ int \ int) (numeral k) (numeral (Num.Bit1 w)) = 1 + 2 * (signed_take_bit :: nat \ int \ int) (pred_numeral k) (numeral w)" "(signed_take_bit :: nat \ int \ int) (numeral k) (- numeral (Num.Bit0 w)) = 2 * (signed_take_bit :: nat \ int \ int) (pred_numeral k) (- numeral w)" "(signed_take_bit :: nat \ int \ int) (numeral k) (- numeral (Num.Bit1 w)) = 1 + 2 * (signed_take_bit :: nat \ int \ int) (pred_numeral k) (- numeral (w + Num.One))" "(signed_take_bit :: nat \ int \ int) (numeral k) 1 = 1" by (simp_all add: sbintrunc_numeral) lemma no_bintr_alt1: "(take_bit :: nat \ int \ int) n = (\w. w mod 2 ^ n :: int)" by (rule ext) (rule bintrunc_mod2p) lemma range_bintrunc: "range ((take_bit :: nat \ int \ int) n) = {i. 0 \ i \ i < 2 ^ n}" by (auto simp add: take_bit_eq_mod image_iff) (metis mod_pos_pos_trivial) lemma no_sbintr_alt2: "(signed_take_bit :: nat \ int \ int) n = (\w. (w + 2 ^ n) mod 2 ^ Suc n - 2 ^ n :: int)" by (rule ext) (simp add : sbintrunc_mod2p) lemma range_sbintrunc: "range ((signed_take_bit :: nat \ int \ int) n) = {i. - (2 ^ n) \ i \ i < 2 ^ n}" proof - have \surj (\k::int. k + 2 ^ n)\ by (rule surjI [of _ \(\k. k - 2 ^ n)\]) simp moreover have \(signed_take_bit :: nat \ int \ int) n = ((\k. k - 2 ^ n) \ take_bit (Suc n) \ (\k. k + 2 ^ n))\ by (simp add: sbintrunc_eq_take_bit fun_eq_iff) ultimately show ?thesis apply (simp only: fun.set_map range_bintrunc) apply (auto simp add: image_iff) apply presburger done qed lemma sbintrunc_inc: \k + 2 ^ Suc n \ (signed_take_bit :: nat \ int \ int) n k\ if \k < - (2 ^ n)\ using that by (fact signed_take_bit_int_greater_eq) lemma sbintrunc_dec: \(signed_take_bit :: nat \ int \ int) n k \ k - 2 ^ (Suc n)\ if \k \ 2 ^ n\ using that by (fact signed_take_bit_int_less_eq) lemma bintr_ge0: "0 \ (take_bit :: nat \ int \ int) n w" by (simp add: bintrunc_mod2p) lemma bintr_lt2p: "(take_bit :: nat \ int \ int) n w < 2 ^ n" by (simp add: bintrunc_mod2p) lemma bintr_Min: "(take_bit :: nat \ int \ int) n (- 1) = 2 ^ n - 1" by (simp add: stable_imp_take_bit_eq) lemma sbintr_ge: "- (2 ^ n) \ (signed_take_bit :: nat \ int \ int) n w" by (fact signed_take_bit_int_greater_eq_minus_exp) lemma sbintr_lt: "(signed_take_bit :: nat \ int \ int) n w < 2 ^ n" by (fact signed_take_bit_int_less_exp) lemma sign_Pls_ge_0: "bin_sign bin = 0 \ bin \ 0" for bin :: int by (simp add: bin_sign_def) lemma sign_Min_lt_0: "bin_sign bin = -1 \ bin < 0" for bin :: int by (simp add: bin_sign_def) lemma bin_rest_trunc: "(\k::int. k div 2) ((take_bit :: nat \ int \ int) n bin) = (take_bit :: nat \ int \ int) (n - 1) ((\k::int. k div 2) bin)" by (simp add: take_bit_rec [of n bin]) lemma bin_rest_power_trunc: "((\k::int. k div 2) ^^ k) ((take_bit :: nat \ int \ int) n bin) = (take_bit :: nat \ int \ int) (n - k) (((\k::int. k div 2) ^^ k) bin)" by (induct k) (auto simp: bin_rest_trunc) lemma bin_rest_trunc_i: "(take_bit :: nat \ int \ int) n ((\k::int. k div 2) bin) = (\k::int. k div 2) ((take_bit :: nat \ int \ int) (Suc n) bin)" by (auto simp add: take_bit_Suc) lemma bin_rest_strunc: "(\k::int. k div 2) ((signed_take_bit :: nat \ int \ int) (Suc n) bin) = (signed_take_bit :: nat \ int \ int) n ((\k::int. k div 2) bin)" by (simp add: signed_take_bit_Suc) lemma bintrunc_rest [simp]: "(take_bit :: nat \ int \ int) n ((\k::int. k div 2) ((take_bit :: nat \ int \ int) n bin)) = (\k::int. k div 2) ((take_bit :: nat \ int \ int) n bin)" by (induct n arbitrary: bin) (simp_all add: take_bit_Suc) lemma sbintrunc_rest [simp]: "(signed_take_bit :: nat \ int \ int) n ((\k::int. k div 2) ((signed_take_bit :: nat \ int \ int) n bin)) = (\k::int. k div 2) ((signed_take_bit :: nat \ int \ int) n bin)" by (induct n arbitrary: bin) (simp_all add: signed_take_bit_Suc mod2_eq_if) lemma bintrunc_rest': "(take_bit :: nat \ int \ int) n \ (\k::int. k div 2) \ (take_bit :: nat \ int \ int) n = (\k::int. k div 2) \ (take_bit :: nat \ int \ int) n" by (rule ext) auto lemma sbintrunc_rest': "(signed_take_bit :: nat \ int \ int) n \ (\k::int. k div 2) \ (signed_take_bit :: nat \ int \ int) n = (\k::int. k div 2) \ (signed_take_bit :: nat \ int \ int) n" by (rule ext) auto lemma rco_lem: "f \ g \ f = g \ f \ f \ (g \ f) ^^ n = g ^^ n \ f" apply (rule ext) apply (induct_tac n) apply (simp_all (no_asm)) apply (drule fun_cong) apply (unfold o_def) apply (erule trans) apply simp done lemmas rco_bintr = bintrunc_rest' [THEN rco_lem [THEN fun_cong], unfolded o_def] lemmas rco_sbintr = sbintrunc_rest' [THEN rco_lem [THEN fun_cong], unfolded o_def] subsection \Splitting and concatenation\ definition bin_split :: \nat \ int \ int \ int\ where [simp]: \bin_split n k = (drop_bit n k, take_bit n k)\ lemma [code]: "bin_split (Suc n) w = (let (w1, w2) = bin_split n (w div 2) in (w1, of_bool (odd w) + 2 * w2))" "bin_split 0 w = (w, 0)" by (simp_all add: drop_bit_Suc take_bit_Suc mod_2_eq_odd) lemma bin_cat_eq_push_bit_add_take_bit: \concat_bit n l k = push_bit n k + take_bit n l\ by (simp add: concat_bit_eq) lemma bin_sign_cat: "bin_sign ((\k n l. concat_bit n l k) x n y) = bin_sign x" proof - have \0 \ x\ if \0 \ x * 2 ^ n + y mod 2 ^ n\ proof - have \y mod 2 ^ n < 2 ^ n\ using pos_mod_bound [of \2 ^ n\ y] by simp then have \\ y mod 2 ^ n \ 2 ^ n\ by (simp add: less_le) with that have \x \ - 1\ by auto have *: \- 1 \ (- (y mod 2 ^ n)) div 2 ^ n\ by (simp add: zdiv_zminus1_eq_if) from that have \- (y mod 2 ^ n) \ x * 2 ^ n\ by simp then have \(- (y mod 2 ^ n)) div 2 ^ n \ (x * 2 ^ n) div 2 ^ n\ using zdiv_mono1 zero_less_numeral zero_less_power by blast with * have \- 1 \ x * 2 ^ n div 2 ^ n\ by simp with \x \ - 1\ show ?thesis by simp qed then show ?thesis by (simp add: bin_sign_def not_le not_less bin_cat_eq_push_bit_add_take_bit push_bit_eq_mult take_bit_eq_mod) qed lemma bin_cat_assoc: "(\k n l. concat_bit n l k) ((\k n l. concat_bit n l k) x m y) n z = (\k n l. concat_bit n l k) x (m + n) ((\k n l. concat_bit n l k) y n z)" by (fact concat_bit_assoc) lemma bin_cat_assoc_sym: "(\k n l. concat_bit n l k) x m ((\k n l. concat_bit n l k) y n z) = (\k n l. concat_bit n l k) ((\k n l. concat_bit n l k) x (m - n) y) (min m n) z" by (fact concat_bit_assoc_sym) definition bin_rcat :: \nat \ int list \ int\ where \bin_rcat n = horner_sum (take_bit n) (2 ^ n) \ rev\ lemma bin_rcat_eq_foldl: \bin_rcat n = foldl (\u v. (\k n l. concat_bit n l k) u n v) 0\ proof fix ks :: \int list\ show \bin_rcat n ks = foldl (\u v. (\k n l. concat_bit n l k) u n v) 0 ks\ by (induction ks rule: rev_induct) (simp_all add: bin_rcat_def concat_bit_eq push_bit_eq_mult) qed fun bin_rsplit_aux :: "nat \ nat \ int \ int list \ int list" where "bin_rsplit_aux n m c bs = (if m = 0 \ n = 0 then bs else let (a, b) = bin_split n c in bin_rsplit_aux n (m - n) a (b # bs))" definition bin_rsplit :: "nat \ nat \ int \ int list" where "bin_rsplit n w = bin_rsplit_aux n (fst w) (snd w) []" fun bin_rsplitl_aux :: "nat \ nat \ int \ int list \ int list" where "bin_rsplitl_aux n m c bs = (if m = 0 \ n = 0 then bs else let (a, b) = bin_split (min m n) c in bin_rsplitl_aux n (m - n) a (b # bs))" definition bin_rsplitl :: "nat \ nat \ int \ int list" where "bin_rsplitl n w = bin_rsplitl_aux n (fst w) (snd w) []" declare bin_rsplit_aux.simps [simp del] declare bin_rsplitl_aux.simps [simp del] lemma bin_nth_cat: "(bit :: int \ nat \ bool) ((\k n l. concat_bit n l k) x k y) n = (if n < k then (bit :: int \ nat \ bool) y n else (bit :: int \ nat \ bool) x (n - k))" by (simp add: bit_concat_bit_iff) lemma bin_nth_drop_bit_iff: \(bit :: int \ nat \ bool) (drop_bit n c) k \ (bit :: int \ nat \ bool) c (n + k)\ by (simp add: bit_drop_bit_eq) lemma bin_nth_take_bit_iff: \(bit :: int \ nat \ bool) (take_bit n c) k \ k < n \ (bit :: int \ nat \ bool) c k\ by (fact bit_take_bit_iff) lemma bin_nth_split: "bin_split n c = (a, b) \ (\k. (bit :: int \ nat \ bool) a k = (bit :: int \ nat \ bool) c (n + k)) \ (\k. (bit :: int \ nat \ bool) b k = (k < n \ (bit :: int \ nat \ bool) c k))" by (auto simp add: bin_nth_drop_bit_iff bin_nth_take_bit_iff) lemma bin_cat_zero [simp]: "(\k n l. concat_bit n l k) 0 n w = (take_bit :: nat \ int \ int) n w" by (simp add: bin_cat_eq_push_bit_add_take_bit) lemma bintr_cat1: "(take_bit :: nat \ int \ int) (k + n) ((\k n l. concat_bit n l k) a n b) = (\k n l. concat_bit n l k) ((take_bit :: nat \ int \ int) k a) n b" by (metis bin_cat_assoc bin_cat_zero) lemma bintr_cat: "(take_bit :: nat \ int \ int) m ((\k n l. concat_bit n l k) a n b) = (\k n l. concat_bit n l k) ((take_bit :: nat \ int \ int) (m - n) a) n ((take_bit :: nat \ int \ int) (min m n) b)" by (rule bin_eqI) (auto simp: bin_nth_cat nth_bintr) lemma bintr_cat_same [simp]: "(take_bit :: nat \ int \ int) n ((\k n l. concat_bit n l k) a n b) = (take_bit :: nat \ int \ int) n b" by (auto simp add : bintr_cat) lemma cat_bintr [simp]: "(\k n l. concat_bit n l k) a n ((take_bit :: nat \ int \ int) n b) = (\k n l. concat_bit n l k) a n b" by (simp add: bin_cat_eq_push_bit_add_take_bit) lemma split_bintrunc: "bin_split n c = (a, b) \ b = (take_bit :: nat \ int \ int) n c" by simp lemma bin_cat_split: "bin_split n w = (u, v) \ w = (\k n l. concat_bit n l k) u n v" by (auto simp add: bin_cat_eq_push_bit_add_take_bit bits_ident) lemma drop_bit_bin_cat_eq: \drop_bit n ((\k n l. concat_bit n l k) v n w) = v\ by (rule bit_eqI) (simp add: bit_drop_bit_eq bit_concat_bit_iff) lemma take_bit_bin_cat_eq: \take_bit n ((\k n l. concat_bit n l k) v n w) = take_bit n w\ by (rule bit_eqI) (simp add: bit_concat_bit_iff) lemma bin_split_cat: "bin_split n ((\k n l. concat_bit n l k) v n w) = (v, (take_bit :: nat \ int \ int) n w)" by (simp add: drop_bit_bin_cat_eq take_bit_bin_cat_eq) lemma bin_split_zero [simp]: "bin_split n 0 = (0, 0)" by simp lemma bin_split_minus1 [simp]: "bin_split n (- 1) = (- 1, (take_bit :: nat \ int \ int) n (- 1))" by simp lemma bin_split_trunc: "bin_split (min m n) c = (a, b) \ bin_split n ((take_bit :: nat \ int \ int) m c) = ((take_bit :: nat \ int \ int) (m - n) a, b)" apply (induct n arbitrary: m b c, clarsimp) apply (simp add: bin_rest_trunc Let_def split: prod.split_asm) apply (case_tac m) apply (auto simp: Let_def drop_bit_Suc take_bit_Suc mod_2_eq_odd split: prod.split_asm) done lemma bin_split_trunc1: "bin_split n c = (a, b) \ bin_split n ((take_bit :: nat \ int \ int) m c) = ((take_bit :: nat \ int \ int) (m - n) a, (take_bit :: nat \ int \ int) m b)" apply (induct n arbitrary: m b c, clarsimp) apply (simp add: bin_rest_trunc Let_def split: prod.split_asm) apply (case_tac m) apply (auto simp: Let_def drop_bit_Suc take_bit_Suc mod_2_eq_odd split: prod.split_asm) done lemma bin_cat_num: "(\k n l. concat_bit n l k) a n b = a * 2 ^ n + (take_bit :: nat \ int \ int) n b" by (simp add: bin_cat_eq_push_bit_add_take_bit push_bit_eq_mult) lemma bin_split_num: "bin_split n b = (b div 2 ^ n, b mod 2 ^ n)" by (simp add: drop_bit_eq_div take_bit_eq_mod) lemmas bin_rsplit_aux_simps = bin_rsplit_aux.simps bin_rsplitl_aux.simps lemmas rsplit_aux_simps = bin_rsplit_aux_simps lemmas th_if_simp1 = if_split [where P = "(=) l", THEN iffD1, THEN conjunct1, THEN mp] for l lemmas th_if_simp2 = if_split [where P = "(=) l", THEN iffD1, THEN conjunct2, THEN mp] for l lemmas rsplit_aux_simp1s = rsplit_aux_simps [THEN th_if_simp1] lemmas rsplit_aux_simp2ls = rsplit_aux_simps [THEN th_if_simp2] \ \these safe to \[simp add]\ as require calculating \m - n\\ lemmas bin_rsplit_aux_simp2s [simp] = rsplit_aux_simp2ls [unfolded Let_def] lemmas rbscl = bin_rsplit_aux_simp2s (2) lemmas rsplit_aux_0_simps [simp] = rsplit_aux_simp1s [OF disjI1] rsplit_aux_simp1s [OF disjI2] lemma bin_rsplit_aux_append: "bin_rsplit_aux n m c (bs @ cs) = bin_rsplit_aux n m c bs @ cs" apply (induct n m c bs rule: bin_rsplit_aux.induct) apply (subst bin_rsplit_aux.simps) apply (subst bin_rsplit_aux.simps) apply (clarsimp split: prod.split) done lemma bin_rsplitl_aux_append: "bin_rsplitl_aux n m c (bs @ cs) = bin_rsplitl_aux n m c bs @ cs" apply (induct n m c bs rule: bin_rsplitl_aux.induct) apply (subst bin_rsplitl_aux.simps) apply (subst bin_rsplitl_aux.simps) apply (clarsimp split: prod.split) done lemmas rsplit_aux_apps [where bs = "[]"] = bin_rsplit_aux_append bin_rsplitl_aux_append lemmas rsplit_def_auxs = bin_rsplit_def bin_rsplitl_def lemmas rsplit_aux_alts = rsplit_aux_apps [unfolded append_Nil rsplit_def_auxs [symmetric]] lemma bin_split_minus: "0 < n \ bin_split (Suc (n - 1)) w = bin_split n w" by auto lemma bin_split_pred_simp [simp]: "(0::nat) < numeral bin \ bin_split (numeral bin) w = (let (w1, w2) = bin_split (numeral bin - 1) ((\k::int. k div 2) w) in (w1, of_bool (odd w) + 2 * w2))" by (simp add: take_bit_rec drop_bit_rec mod_2_eq_odd) lemma bin_rsplit_aux_simp_alt: "bin_rsplit_aux n m c bs = (if m = 0 \ n = 0 then bs else let (a, b) = bin_split n c in bin_rsplit n (m - n, a) @ b # bs)" apply (simp add: bin_rsplit_aux.simps [of n m c bs]) apply (subst rsplit_aux_alts) apply (simp add: bin_rsplit_def) done lemmas bin_rsplit_simp_alt = trans [OF bin_rsplit_def bin_rsplit_aux_simp_alt] lemmas bthrs = bin_rsplit_simp_alt [THEN [2] trans] lemma bin_rsplit_size_sign' [rule_format]: "n > 0 \ rev sw = bin_rsplit n (nw, w) \ \v\set sw. (take_bit :: nat \ int \ int) n v = v" apply (induct sw arbitrary: nw w) apply clarsimp apply clarsimp apply (drule bthrs) apply (simp (no_asm_use) add: Let_def split: prod.split_asm if_split_asm) apply clarify apply simp done lemmas bin_rsplit_size_sign = bin_rsplit_size_sign' [OF asm_rl rev_rev_ident [THEN trans] set_rev [THEN equalityD2 [THEN subsetD]]] lemma bin_nth_rsplit [rule_format] : "n > 0 \ m < n \ \w k nw. rev sw = bin_rsplit n (nw, w) \ k < size sw \ (bit :: int \ nat \ bool) (sw ! k) m = (bit :: int \ nat \ bool) w (k * n + m)" apply (induct sw) apply clarsimp apply clarsimp apply (drule bthrs) apply (simp (no_asm_use) add: Let_def split: prod.split_asm if_split_asm) apply (erule allE, erule impE, erule exI) apply (case_tac k) apply clarsimp prefer 2 apply clarsimp apply (erule allE) apply (erule (1) impE) apply (simp add: bit_drop_bit_eq ac_simps) apply (simp add: bit_take_bit_iff ac_simps) done lemma bin_rsplit_all: "0 < nw \ nw \ n \ bin_rsplit n (nw, w) = [(take_bit :: nat \ int \ int) n w]" by (auto simp: bin_rsplit_def rsplit_aux_simp2ls split: prod.split dest!: split_bintrunc) lemma bin_rsplit_l [rule_format]: "\bin. bin_rsplitl n (m, bin) = bin_rsplit n (m, (take_bit :: nat \ int \ int) m bin)" apply (rule_tac a = "m" in wf_less_than [THEN wf_induct]) apply (simp (no_asm) add: bin_rsplitl_def bin_rsplit_def) apply (rule allI) apply (subst bin_rsplitl_aux.simps) apply (subst bin_rsplit_aux.simps) apply (clarsimp simp: Let_def split: prod.split) apply (simp add: ac_simps) apply (subst rsplit_aux_alts(1)) apply (subst rsplit_aux_alts(2)) apply clarsimp unfolding bin_rsplit_def bin_rsplitl_def apply (simp add: drop_bit_take_bit) apply (case_tac \x < n\) apply (simp_all add: not_less min_def) done lemma bin_rsplit_rcat [rule_format]: "n > 0 \ bin_rsplit n (n * size ws, bin_rcat n ws) = map ((take_bit :: nat \ int \ int) n) ws" apply (unfold bin_rsplit_def bin_rcat_eq_foldl) apply (rule_tac xs = ws in rev_induct) apply clarsimp apply clarsimp apply (subst rsplit_aux_alts) apply (simp add: drop_bit_bin_cat_eq take_bit_bin_cat_eq) done lemma bin_rsplit_aux_len_le [rule_format] : "\ws m. n \ 0 \ ws = bin_rsplit_aux n nw w bs \ length ws \ m \ nw + length bs * n \ m * n" proof - have *: R if d: "i \ j \ m < j'" and R1: "i * k \ j * k \ R" and R2: "Suc m * k' \ j' * k' \ R" for i j j' k k' m :: nat and R using d apply safe apply (rule R1, erule mult_le_mono1) apply (rule R2, erule Suc_le_eq [THEN iffD2 [THEN mult_le_mono1]]) done have **: "0 < sc \ sc - n + (n + lb * n) \ m * n \ sc + lb * n \ m * n" for sc m n lb :: nat apply safe apply arith apply (case_tac "sc \ n") apply arith apply (insert linorder_le_less_linear [of m lb]) apply (erule_tac k=n and k'=n in *) apply arith apply simp done show ?thesis apply (induct n nw w bs rule: bin_rsplit_aux.induct) apply (subst bin_rsplit_aux.simps) apply (simp add: ** Let_def split: prod.split) done qed lemma bin_rsplit_len_le: "n \ 0 \ ws = bin_rsplit n (nw, w) \ length ws \ m \ nw \ m * n" by (auto simp: bin_rsplit_def bin_rsplit_aux_len_le) lemma bin_rsplit_aux_len: "n \ 0 \ length (bin_rsplit_aux n nw w cs) = (nw + n - 1) div n + length cs" apply (induct n nw w cs rule: bin_rsplit_aux.induct) apply (subst bin_rsplit_aux.simps) apply (clarsimp simp: Let_def split: prod.split) apply (erule thin_rl) apply (case_tac m) apply simp apply (case_tac "m \ n") apply (auto simp add: div_add_self2) done lemma bin_rsplit_len: "n \ 0 \ length (bin_rsplit n (nw, w)) = (nw + n - 1) div n" by (auto simp: bin_rsplit_def bin_rsplit_aux_len) lemma bin_rsplit_aux_len_indep: "n \ 0 \ length bs = length cs \ length (bin_rsplit_aux n nw v bs) = length (bin_rsplit_aux n nw w cs)" proof (induct n nw w cs arbitrary: v bs rule: bin_rsplit_aux.induct) case (1 n m w cs v bs) show ?case proof (cases "m = 0") case True with \length bs = length cs\ show ?thesis by simp next case False from "1.hyps" [of \bin_split n w\ \drop_bit n w\ \take_bit n w\] \m \ 0\ \n \ 0\ have hyp: "\v bs. length bs = Suc (length cs) \ length (bin_rsplit_aux n (m - n) v bs) = length (bin_rsplit_aux n (m - n) (drop_bit n w) (take_bit n w # cs))" using bin_rsplit_aux_len by fastforce from \length bs = length cs\ \n \ 0\ show ?thesis by (auto simp add: bin_rsplit_aux_simp_alt Let_def bin_rsplit_len split: prod.split) qed qed lemma bin_rsplit_len_indep: "n \ 0 \ length (bin_rsplit n (nw, v)) = length (bin_rsplit n (nw, w))" apply (unfold bin_rsplit_def) apply (simp (no_asm)) apply (erule bin_rsplit_aux_len_indep) apply (rule refl) done subsection \Logical operations\ abbreviation (input) bin_sc :: \nat \ bool \ int \ int\ where \bin_sc n b i \ set_bit i n b\ lemma bin_sc_0 [simp]: "bin_sc 0 b w = of_bool b + 2 * (\k::int. k div 2) w" by (simp add: set_bit_int_def) lemma bin_sc_Suc [simp]: "bin_sc (Suc n) b w = of_bool (odd w) + 2 * bin_sc n b (w div 2)" by (simp add: set_bit_int_def set_bit_Suc unset_bit_Suc bin_last_def) lemma bin_nth_sc [bit_simps]: "bit (bin_sc n b w) n \ b" by (simp add: bit_simps) lemma bin_sc_sc_same [simp]: "bin_sc n c (bin_sc n b w) = bin_sc n c w" by (induction n arbitrary: w) (simp_all add: bit_Suc) lemma bin_sc_sc_diff: "m \ n \ bin_sc m c (bin_sc n b w) = bin_sc n b (bin_sc m c w)" apply (induct n arbitrary: w m) apply (case_tac [!] m) apply auto done lemma bin_nth_sc_gen: "(bit :: int \ nat \ bool) (bin_sc n b w) m = (if m = n then b else (bit :: int \ nat \ bool) w m)" apply (induct n arbitrary: w m) apply (case_tac m; simp add: bit_Suc) apply (case_tac m; simp add: bit_Suc) done lemma bin_sc_eq: \bin_sc n False = unset_bit n\ \bin_sc n True = Bit_Operations.set_bit n\ apply (simp_all add: fun_eq_iff bit_eq_iff) apply (simp_all add: bit_simps bin_nth_sc_gen) done lemma bin_sc_nth [simp]: "bin_sc n ((bit :: int \ nat \ bool) w n) w = w" by (rule bit_eqI) (simp add: bin_nth_sc_gen) lemma bin_sign_sc [simp]: "bin_sign (bin_sc n b w) = bin_sign w" proof (induction n arbitrary: w) case 0 then show ?case by (auto simp add: bin_sign_def) (use bin_rest_ge_0 in fastforce) next case (Suc n) from Suc [of \w div 2\] show ?case by (auto simp add: bin_sign_def split: if_splits) qed lemma bin_sc_bintr [simp]: "(take_bit :: nat \ int \ int) m (bin_sc n x ((take_bit :: nat \ int \ int) m w)) = (take_bit :: nat \ int \ int) m (bin_sc n x w)" apply (rule bit_eqI) apply (cases x) apply (auto simp add: bit_simps bin_sc_eq) done lemma bin_clr_le: "bin_sc n False w \ w" by (simp add: set_bit_int_def unset_bit_less_eq) lemma bin_set_ge: "bin_sc n True w \ w" by (simp add: set_bit_int_def set_bit_greater_eq) lemma bintr_bin_clr_le: "(take_bit :: nat \ int \ int) n (bin_sc m False w) \ (take_bit :: nat \ int \ int) n w" by (simp add: set_bit_int_def take_bit_unset_bit_eq unset_bit_less_eq) lemma bintr_bin_set_ge: "(take_bit :: nat \ int \ int) n (bin_sc m True w) \ (take_bit :: nat \ int \ int) n w" by (simp add: set_bit_int_def take_bit_set_bit_eq set_bit_greater_eq) lemma bin_sc_FP [simp]: "bin_sc n False 0 = 0" by (induct n) auto lemma bin_sc_TM [simp]: "bin_sc n True (- 1) = - 1" by (induct n) auto lemmas bin_sc_simps = bin_sc_0 bin_sc_Suc bin_sc_TM bin_sc_FP lemma bin_sc_minus: "0 < n \ bin_sc (Suc (n - 1)) b w = bin_sc n b w" by auto lemmas bin_sc_Suc_minus = trans [OF bin_sc_minus [symmetric] bin_sc_Suc] lemma bin_sc_numeral [simp]: "bin_sc (numeral k) b w = of_bool (odd w) + 2 * bin_sc (pred_numeral k) b (w div 2)" by (simp add: numeral_eq_Suc) lemmas bin_sc_minus_simps = bin_sc_simps (2,3,4) [THEN [2] trans, OF bin_sc_minus [THEN sym]] lemma int_set_bit_0 [simp]: fixes x :: int shows "set_bit x 0 b = of_bool b + 2 * (x div 2)" by (fact bin_sc_0) lemma int_set_bit_Suc: fixes x :: int shows "set_bit x (Suc n) b = of_bool (odd x) + 2 * set_bit (x div 2) n b" by (fact bin_sc_Suc) lemma bin_last_set_bit: "odd (set_bit x n b :: int) = (if n > 0 then odd x else b)" by (cases n) (simp_all add: int_set_bit_Suc) lemma bin_rest_set_bit: "(set_bit x n b :: int) div 2 = (if n > 0 then set_bit (x div 2) (n - 1) b else x div 2)" by (cases n) (simp_all add: int_set_bit_Suc) lemma int_set_bit_numeral: fixes x :: int shows "set_bit x (numeral w) b = of_bool (odd x) + 2 * set_bit (x div 2) (pred_numeral w) b" by (fact bin_sc_numeral) lemmas int_set_bit_numerals [simp] = int_set_bit_numeral[where x="numeral w'"] int_set_bit_numeral[where x="- numeral w'"] int_set_bit_numeral[where x="Numeral1"] int_set_bit_numeral[where x="1"] int_set_bit_numeral[where x="0"] int_set_bit_Suc[where x="numeral w'"] int_set_bit_Suc[where x="- numeral w'"] int_set_bit_Suc[where x="Numeral1"] int_set_bit_Suc[where x="1"] int_set_bit_Suc[where x="0"] for w' lemma msb_set_bit [simp]: "msb (set_bit (x :: int) n b) \ msb x" by (simp add: msb_int_def set_bit_int_def) lemma word_set_bit_def: \set_bit a n x = word_of_int (bin_sc n x (uint a))\ apply (rule bit_word_eqI) apply (cases x) apply (simp_all add: bit_simps bin_sc_eq) done lemma set_bit_word_of_int: "set_bit (word_of_int x) n b = word_of_int (bin_sc n b x)" unfolding word_set_bit_def by (rule word_eqI) (simp add: word_size bin_nth_sc_gen nth_bintr bit_simps) lemma word_set_numeral [simp]: "set_bit (numeral bin::'a::len word) n b = word_of_int (bin_sc n b (numeral bin))" unfolding word_numeral_alt by (rule set_bit_word_of_int) lemma word_set_neg_numeral [simp]: "set_bit (- numeral bin::'a::len word) n b = word_of_int (bin_sc n b (- numeral bin))" unfolding word_neg_numeral_alt by (rule set_bit_word_of_int) lemma word_set_bit_0 [simp]: "set_bit 0 n b = word_of_int (bin_sc n b 0)" unfolding word_0_wi by (rule set_bit_word_of_int) lemma word_set_bit_1 [simp]: "set_bit 1 n b = word_of_int (bin_sc n b 1)" unfolding word_1_wi by (rule set_bit_word_of_int) lemma shiftl_int_def: "push_bit n x = x * 2 ^ n" for x :: int by (fact push_bit_eq_mult) lemma shiftr_int_def: "drop_bit n x = x div 2 ^ n" for x :: int by (fact drop_bit_eq_div) subsubsection \Basic simplification rules\ context includes bit_operations_syntax begin lemmas int_not_def = not_int_def lemma int_not_simps: "NOT (0::int) = -1" "NOT (1::int) = -2" "NOT (- 1::int) = 0" "NOT (numeral w::int) = - numeral (w + Num.One)" "NOT (- numeral (Num.Bit0 w)::int) = numeral (Num.BitM w)" "NOT (- numeral (Num.Bit1 w)::int) = numeral (Num.Bit0 w)" by (simp_all add: not_int_def) lemma int_not_not: "NOT (NOT x) = x" for x :: int by (fact bit.double_compl) lemma int_and_0 [simp]: "0 AND x = 0" for x :: int by (fact bit.conj_zero_left) lemma int_and_m1 [simp]: "-1 AND x = x" for x :: int by (fact and.left_neutral) lemma int_or_zero [simp]: "0 OR x = x" for x :: int by (fact or.left_neutral) lemma int_or_minus1 [simp]: "-1 OR x = -1" for x :: int by (fact bit.disj_one_left) lemma int_xor_zero [simp]: "0 XOR x = x" for x :: int by (fact xor.left_neutral) subsubsection \Binary destructors\ lemma bin_rest_NOT [simp]: "(\k::int. k div 2) (NOT x) = NOT ((\k::int. k div 2) x)" by (fact not_int_div_2) lemma bin_last_NOT [simp]: "(odd :: int \ bool) (NOT x) \ \ (odd :: int \ bool) x" by simp lemma bin_rest_AND [simp]: "(\k::int. k div 2) (x AND y) = (\k::int. k div 2) x AND (\k::int. k div 2) y" by (subst and_int_rec) auto lemma bin_last_AND [simp]: "(odd :: int \ bool) (x AND y) \ (odd :: int \ bool) x \ (odd :: int \ bool) y" by (subst and_int_rec) auto lemma bin_rest_OR [simp]: "(\k::int. k div 2) (x OR y) = (\k::int. k div 2) x OR (\k::int. k div 2) y" by (subst or_int_rec) auto lemma bin_last_OR [simp]: "(odd :: int \ bool) (x OR y) \ (odd :: int \ bool) x \ (odd :: int \ bool) y" by (subst or_int_rec) auto lemma bin_rest_XOR [simp]: "(\k::int. k div 2) (x XOR y) = (\k::int. k div 2) x XOR (\k::int. k div 2) y" by (subst xor_int_rec) auto lemma bin_last_XOR [simp]: "(odd :: int \ bool) (x XOR y) \ ((odd :: int \ bool) x \ (odd :: int \ bool) y) \ \ ((odd :: int \ bool) x \ (odd :: int \ bool) y)" by (subst xor_int_rec) auto lemma bin_nth_ops: "\x y. (bit :: int \ nat \ bool) (x AND y) n \ (bit :: int \ nat \ bool) x n \ (bit :: int \ nat \ bool) y n" "\x y. (bit :: int \ nat \ bool) (x OR y) n \ (bit :: int \ nat \ bool) x n \ (bit :: int \ nat \ bool) y n" "\x y. (bit :: int \ nat \ bool) (x XOR y) n \ (bit :: int \ nat \ bool) x n \ (bit :: int \ nat \ bool) y n" "\x. (bit :: int \ nat \ bool) (NOT x) n \ \ (bit :: int \ nat \ bool) x n" by (simp_all add: bit_and_iff bit_or_iff bit_xor_iff bit_not_iff) subsubsection \Derived properties\ lemma int_xor_minus1 [simp]: "-1 XOR x = NOT x" for x :: int by (fact bit.xor_one_left) lemma int_xor_extra_simps [simp]: "w XOR 0 = w" "w XOR -1 = NOT w" for w :: int by simp_all lemma int_or_extra_simps [simp]: "w OR 0 = w" "w OR -1 = -1" for w :: int by simp_all lemma int_and_extra_simps [simp]: "w AND 0 = 0" "w AND -1 = w" for w :: int by simp_all text \Commutativity of the above.\ lemma bin_ops_comm: fixes x y :: int shows int_and_comm: "x AND y = y AND x" and int_or_comm: "x OR y = y OR x" and int_xor_comm: "x XOR y = y XOR x" by (simp_all add: ac_simps) lemma bin_ops_same [simp]: "x AND x = x" "x OR x = x" "x XOR x = 0" for x :: int by simp_all lemmas bin_log_esimps = int_and_extra_simps int_or_extra_simps int_xor_extra_simps int_and_0 int_and_m1 int_or_zero int_or_minus1 int_xor_zero int_xor_minus1 subsubsection \Basic properties of logical (bit-wise) operations\ lemma bbw_ao_absorb: "x AND (y OR x) = x \ x OR (y AND x) = x" for x y :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemma bbw_ao_absorbs_other: "x AND (x OR y) = x \ (y AND x) OR x = x" "(y OR x) AND x = x \ x OR (x AND y) = x" "(x OR y) AND x = x \ (x AND y) OR x = x" for x y :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemmas bbw_ao_absorbs [simp] = bbw_ao_absorb bbw_ao_absorbs_other lemma int_xor_not: "(NOT x) XOR y = NOT (x XOR y) \ x XOR (NOT y) = NOT (x XOR y)" for x y :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemma int_and_assoc: "(x AND y) AND z = x AND (y AND z)" for x y z :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemma int_or_assoc: "(x OR y) OR z = x OR (y OR z)" for x y z :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemma int_xor_assoc: "(x XOR y) XOR z = x XOR (y XOR z)" for x y z :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemmas bbw_assocs = int_and_assoc int_or_assoc int_xor_assoc (* BH: Why are these declared as simp rules??? *) lemma bbw_lcs [simp]: "y AND (x AND z) = x AND (y AND z)" "y OR (x OR z) = x OR (y OR z)" "y XOR (x XOR z) = x XOR (y XOR z)" for x y :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemma bbw_not_dist: "NOT (x OR y) = (NOT x) AND (NOT y)" "NOT (x AND y) = (NOT x) OR (NOT y)" for x y :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemma bbw_oa_dist: "(x AND y) OR z = (x OR z) AND (y OR z)" for x y z :: int by (auto simp add: bin_eq_iff bin_nth_ops) lemma bbw_ao_dist: "(x OR y) AND z = (x AND z) OR (y AND z)" for x y z :: int by (auto simp add: bin_eq_iff bin_nth_ops) subsubsection \Simplification with numerals\ text \Cases for \0\ and \-1\ are already covered by other simp rules.\ lemma bin_rest_neg_numeral_BitM [simp]: "(\k::int. k div 2) (- numeral (Num.BitM w)) = - numeral w" by simp lemma bin_last_neg_numeral_BitM [simp]: "(odd :: int \ bool) (- numeral (Num.BitM w))" by simp subsubsection \Interactions with arithmetic\ lemma le_int_or: "bin_sign y = 0 \ x \ x OR y" for x y :: int by (simp add: bin_sign_def or_greater_eq split: if_splits) lemmas int_and_le = xtrans(3) [OF bbw_ao_absorbs (2) [THEN conjunct2, symmetric] le_int_or] text \Interaction between bit-wise and arithmetic: good example of \bin_induction\.\ lemma bin_add_not: "x + NOT x = (-1::int)" by (simp add: not_int_def) lemma AND_mod: "x AND (2 ^ n - 1) = x mod 2 ^ n" for x :: int by (simp flip: take_bit_eq_mod add: take_bit_eq_mask mask_eq_exp_minus_1) subsubsection \Truncating results of bit-wise operations\ lemma bin_trunc_ao: "(take_bit :: nat \ int \ int) n x AND (take_bit :: nat \ int \ int) n y = (take_bit :: nat \ int \ int) n (x AND y)" "(take_bit :: nat \ int \ int) n x OR (take_bit :: nat \ int \ int) n y = (take_bit :: nat \ int \ int) n (x OR y)" by simp_all lemma bin_trunc_xor: "(take_bit :: nat \ int \ int) n ((take_bit :: nat \ int \ int) n x XOR (take_bit :: nat \ int \ int) n y) = (take_bit :: nat \ int \ int) n (x XOR y)" by simp lemma bin_trunc_not: "(take_bit :: nat \ int \ int) n (NOT ((take_bit :: nat \ int \ int) n x)) = (take_bit :: nat \ int \ int) n (NOT x)" by (fact take_bit_not_take_bit) text \Want theorems of the form of \bin_trunc_xor\.\ lemma bintr_bintr_i: "x = (take_bit :: nat \ int \ int) n y \ (take_bit :: nat \ int \ int) n x = (take_bit :: nat \ int \ int) n y" by auto lemmas bin_trunc_and = bin_trunc_ao(1) [THEN bintr_bintr_i] lemmas bin_trunc_or = bin_trunc_ao(2) [THEN bintr_bintr_i] subsubsection \More lemmas\ lemma not_int_cmp_0 [simp]: fixes i :: int shows "0 < NOT i \ i < -1" "0 \ NOT i \ i < 0" "NOT i < 0 \ i \ 0" "NOT i \ 0 \ i \ -1" by(simp_all add: int_not_def) arith+ lemma bbw_ao_dist2: "(x :: int) AND (y OR z) = x AND y OR x AND z" by (fact bit.conj_disj_distrib) lemmas int_and_ac = bbw_lcs(1) int_and_comm int_and_assoc lemma int_nand_same [simp]: fixes x :: int shows "x AND NOT x = 0" by simp lemma int_nand_same_middle: fixes x :: int shows "x AND y AND NOT x = 0" by (simp add: bit_eq_iff bit_and_iff bit_not_iff) lemma and_xor_dist: fixes x :: int shows "x AND (y XOR z) = (x AND y) XOR (x AND z)" by (fact bit.conj_xor_distrib) lemma int_and_lt0 [simp]: \x AND y < 0 \ x < 0 \ y < 0\ for x y :: int by (fact and_negative_int_iff) lemma int_and_ge0 [simp]: \x AND y \ 0 \ x \ 0 \ y \ 0\ for x y :: int by (fact and_nonnegative_int_iff) lemma int_and_1: fixes x :: int shows "x AND 1 = x mod 2" by (fact and_one_eq) lemma int_1_and: fixes x :: int shows "1 AND x = x mod 2" by (fact one_and_eq) lemma int_or_lt0 [simp]: \x OR y < 0 \ x < 0 \ y < 0\ for x y :: int by (fact or_negative_int_iff) lemma int_or_ge0 [simp]: \x OR y \ 0 \ x \ 0 \ y \ 0\ for x y :: int by (fact or_nonnegative_int_iff) lemma int_xor_lt0 [simp]: \x XOR y < 0 \ (x < 0) \ (y < 0)\ for x y :: int by (fact xor_negative_int_iff) lemma int_xor_ge0 [simp]: \x XOR y \ 0 \ (x \ 0 \ y \ 0)\ for x y :: int by (fact xor_nonnegative_int_iff) lemma even_conv_AND: \even i \ i AND 1 = 0\ for i :: int by (simp add: and_one_eq mod2_eq_if) lemma bin_last_conv_AND: "(odd :: int \ bool) i \ i AND 1 \ 0" by (simp add: and_one_eq mod2_eq_if) lemma bitval_bin_last: "of_bool ((odd :: int \ bool) i) = i AND 1" by (simp add: and_one_eq mod2_eq_if) lemma bin_sign_and: "bin_sign (i AND j) = - (bin_sign i * bin_sign j)" by(simp add: bin_sign_def) lemma int_not_neg_numeral: "NOT (- numeral n) = (Num.sub n num.One :: int)" by(simp add: int_not_def) lemma int_neg_numeral_pOne_conv_not: "- numeral (n + num.One) = (NOT (numeral n) :: int)" by(simp add: int_not_def) subsection \Setting and clearing bits\ lemma int_shiftl_BIT: fixes x :: int shows int_shiftl0: "push_bit 0 x = x" and int_shiftl_Suc: "push_bit (Suc n) x = 2 * push_bit n x" by (auto simp add: shiftl_int_def) lemma int_0_shiftl: "push_bit n 0 = (0 :: int)" by (fact push_bit_of_0) lemma bin_last_shiftl: "odd (push_bit n x) \ n = 0 \ (odd :: int \ bool) x" by simp lemma bin_rest_shiftl: "(\k::int. k div 2) (push_bit n x) = (if n > 0 then push_bit (n - 1) x else (\k::int. k div 2) x)" by (cases n) (simp_all add: push_bit_eq_mult) lemma bin_nth_shiftl: "(bit :: int \ nat \ bool) (push_bit n x) m \ n \ m \ (bit :: int \ nat \ bool) x (m - n)" by (fact bit_push_bit_iff_int) lemma bin_last_shiftr: "odd (drop_bit n x) \ bit x n" for x :: int by (simp add: bit_iff_odd_drop_bit) lemma bin_rest_shiftr: "(\k::int. k div 2) (drop_bit n x) = drop_bit (Suc n) x" by (simp add: drop_bit_Suc drop_bit_half) lemma bin_nth_shiftr: "(bit :: int \ nat \ bool) (drop_bit n x) m = (bit :: int \ nat \ bool) x (n + m)" by (simp add: bit_simps) lemma bin_nth_conv_AND: fixes x :: int shows "(bit :: int \ nat \ bool) x n \ x AND (push_bit n 1) \ 0" by (fact bit_iff_and_push_bit_not_eq_0) lemma int_shiftl_numeral [simp]: "push_bit (numeral w') (numeral w :: int) = push_bit (pred_numeral w') (numeral (num.Bit0 w))" "push_bit (numeral w') (- numeral w :: int) = push_bit (pred_numeral w') (- numeral (num.Bit0 w))" by(simp_all add: numeral_eq_Suc shiftl_int_def) (metis add_One mult_inc semiring_norm(11) semiring_norm(13) semiring_norm(2) semiring_norm(6) semiring_norm(87))+ lemma int_shiftl_One_numeral [simp]: "push_bit (numeral w) (1::int) = push_bit (pred_numeral w) 2" using int_shiftl_numeral [of Num.One w] by (simp add: numeral_eq_Suc) lemma shiftl_ge_0: fixes i :: int shows "push_bit n i \ 0 \ i \ 0" by (fact push_bit_nonnegative_int_iff) lemma shiftl_lt_0: fixes i :: int shows "push_bit n i < 0 \ i < 0" by (fact push_bit_negative_int_iff) lemma int_shiftl_test_bit: "bit (push_bit i n :: int) m \ m \ i \ bit n (m - i)" by (fact bit_push_bit_iff_int) lemma int_0shiftr: "drop_bit x (0 :: int) = 0" by (fact drop_bit_of_0) lemma int_minus1_shiftr: "drop_bit x (-1 :: int) = -1" by (fact drop_bit_minus_one) lemma int_shiftr_ge_0: fixes i :: int shows "drop_bit n i \ 0 \ i \ 0" by (fact drop_bit_nonnegative_int_iff) lemma int_shiftr_lt_0 [simp]: fixes i :: int shows "drop_bit n i < 0 \ i < 0" by (fact drop_bit_negative_int_iff) lemma int_shiftr_numeral [simp]: "drop_bit (numeral w') (1 :: int) = 0" "drop_bit (numeral w') (numeral num.One :: int) = 0" "drop_bit (numeral w') (numeral (num.Bit0 w) :: int) = drop_bit (pred_numeral w') (numeral w)" "drop_bit (numeral w') (numeral (num.Bit1 w) :: int) = drop_bit (pred_numeral w') (numeral w)" "drop_bit (numeral w') (- numeral (num.Bit0 w) :: int) = drop_bit (pred_numeral w') (- numeral w)" "drop_bit (numeral w') (- numeral (num.Bit1 w) :: int) = drop_bit (pred_numeral w') (- numeral (Num.inc w))" by (simp_all add: numeral_eq_Suc add_One drop_bit_Suc) lemma int_shiftr_numeral_Suc0 [simp]: "drop_bit (Suc 0) (1 :: int) = 0" "drop_bit (Suc 0) (numeral num.One :: int) = 0" "drop_bit (Suc 0) (numeral (num.Bit0 w) :: int) = numeral w" "drop_bit (Suc 0) (numeral (num.Bit1 w) :: int) = numeral w" "drop_bit (Suc 0) (- numeral (num.Bit0 w) :: int) = - numeral w" "drop_bit (Suc 0) (- numeral (num.Bit1 w) :: int) = - numeral (Num.inc w)" by (simp_all add: drop_bit_Suc add_One) lemma bin_nth_minus_p2: assumes sign: "bin_sign x = 0" and y: "y = push_bit n 1" and m: "m < n" and x: "x < y" shows "bit (x - y) m = bit x m" proof - from sign y x have \x \ 0\ and \y = 2 ^ n\ and \x < 2 ^ n\ by (simp_all add: bin_sign_def push_bit_eq_mult split: if_splits) from \0 \ x\ \x < 2 ^ n\ \m < n\ have \bit x m \ bit (x - 2 ^ n) m\ proof (induction m arbitrary: x n) case 0 then show ?case by simp next case (Suc m) moreover define q where \q = n - 1\ ultimately have n: \n = Suc q\ by simp have \(x - 2 ^ Suc q) div 2 = x div 2 - 2 ^ q\ by simp moreover from Suc.IH [of \x div 2\ q] Suc.prems have \bit (x div 2) m \ bit (x div 2 - 2 ^ q) m\ by (simp add: n) ultimately show ?case by (simp add: bit_Suc n) qed with \y = 2 ^ n\ show ?thesis by simp qed lemma bin_clr_conv_NAND: "bin_sc n False i = i AND NOT (push_bit n 1)" by (rule bit_eqI) (auto simp add: bin_sc_eq bit_simps) lemma bin_set_conv_OR: "bin_sc n True i = i OR (push_bit n 1)" by (rule bit_eqI) (auto simp add: bin_sc_eq bit_simps) end subsection \More lemmas on words\ lemma msb_conv_bin_sign: "msb x \ bin_sign x = -1" by (simp add: bin_sign_def not_le msb_int_def) lemma msb_bin_sc [simp]: "msb (bin_sc n b x) \ msb x" by (simp add: msb_conv_bin_sign) lemma msb_word_def: \msb a \ bin_sign (signed_take_bit (LENGTH('a) - 1) (uint a)) = - 1\ for a :: \'a::len word\ by (simp add: bin_sign_def bit_simps msb_word_iff_bit) lemma word_msb_def: "msb a \ bin_sign (sint a) = - 1" by (simp add: msb_word_def sint_uint) lemma word_rcat_eq: \word_rcat ws = word_of_int (bin_rcat (LENGTH('a::len)) (map uint ws))\ for ws :: \'a::len word list\ apply (simp add: word_rcat_def bin_rcat_def rev_map) apply transfer apply (simp add: horner_sum_foldr foldr_map comp_def) done lemma sign_uint_Pls [simp]: "bin_sign (uint x) = 0" by (simp add: sign_Pls_ge_0) lemmas bin_log_bintrs = bin_trunc_not bin_trunc_xor bin_trunc_and bin_trunc_or \ \following definitions require both arithmetic and bit-wise word operations\ \ \to get \word_no_log_defs\ from \word_log_defs\, using \bin_log_bintrs\\ lemmas wils1 = bin_log_bintrs [THEN word_of_int_eq_iff [THEN iffD2], folded uint_word_of_int_eq, THEN eq_reflection] \ \the binary operations only\ (* BH: why is this needed? *) lemmas word_log_binary_defs = word_and_def word_or_def word_xor_def lemma setBit_no: "Bit_Operations.set_bit n (numeral bin) = word_of_int (bin_sc n True (numeral bin))" by (rule bit_word_eqI) (simp add: bit_simps) lemma clearBit_no: "unset_bit n (numeral bin) = word_of_int (bin_sc n False (numeral bin))" by (rule bit_word_eqI) (simp add: bit_simps) lemma eq_mod_iff: "0 < n \ b = b mod n \ 0 \ b \ b < n" for b n :: int by auto (metis pos_mod_conj)+ lemma split_uint_lem: "bin_split n (uint w) = (a, b) \ a = take_bit (LENGTH('a) - n) a \ b = take_bit (LENGTH('a)) b" for w :: "'a::len word" by transfer (simp add: drop_bit_take_bit ac_simps) \ \limited hom result\ lemma word_cat_hom: "LENGTH('a::len) \ LENGTH('b::len) + LENGTH('c::len) \ (word_cat (word_of_int w :: 'b word) (b :: 'c word) :: 'a word) = word_of_int ((\k n l. concat_bit n l k) w (size b) (uint b))" by transfer (simp add: take_bit_concat_bit_eq) lemma bintrunc_shiftl: "take_bit n (push_bit i m) = push_bit i (take_bit (n - i) m)" for m :: int by (fact take_bit_push_bit) lemma uint_shiftl: "uint (push_bit i n) = take_bit (size n) (push_bit i (uint n))" by (simp add: unsigned_push_bit_eq word_size) lemma bin_mask_conv_pow2: "mask n = 2 ^ n - (1 :: int)" by (fact mask_eq_exp_minus_1) lemma bin_mask_ge0: "mask n \ (0 :: int)" by (fact mask_nonnegative_int) context includes bit_operations_syntax begin lemma and_bin_mask_conv_mod: "x AND mask n = x mod 2 ^ n" for x :: int by (simp flip: take_bit_eq_mod add: take_bit_eq_mask) end lemma bin_mask_numeral: "mask (numeral n) = (1 :: int) + 2 * mask (pred_numeral n)" by (fact mask_numeral) lemma bin_nth_mask: "bit (mask n :: int) i \ i < n" by (simp add: bit_mask_iff) lemma bin_sign_mask [simp]: "bin_sign (mask n) = 0" by (simp add: bin_sign_def bin_mask_conv_pow2) lemma bin_mask_p1_conv_shift: "mask n + 1 = push_bit n (1 :: int)" by (simp add: bin_mask_conv_pow2 shiftl_int_def) lemma sbintrunc_eq_in_range: "((signed_take_bit :: nat \ int \ int) n x = x) = (x \ range ((signed_take_bit :: nat \ int \ int) n))" "(x = (signed_take_bit :: nat \ int \ int) n x) = (x \ range ((signed_take_bit :: nat \ int \ int) n))" apply (simp_all add: image_def) apply (metis sbintrunc_sbintrunc)+ done lemma sbintrunc_If: "- 3 * (2 ^ n) \ x \ x < 3 * (2 ^ n) \ (signed_take_bit :: nat \ int \ int) n x = (if x < - (2 ^ n) then x + 2 * (2 ^ n) else if x \ 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 sint_range': \- (2 ^ (LENGTH('a) - Suc 0)) \ sint x \ sint x < 2 ^ (LENGTH('a) - Suc 0)\ for x :: \'a::len word\ apply transfer using sbintr_ge sbintr_lt apply auto 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) lemma signed_mult_eq_checks_double_size: assumes mult_le: "(2 ^ (len_of TYPE ('a) - 1) + 1) ^ 2 \ (2 :: int) ^ (len_of TYPE ('b) - 1)" and le: "2 ^ (LENGTH('a) - 1) \ (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: "(signed_take_bit :: nat \ int \ int) (size a - 1) (sint a * sint b) \ range ((signed_take_bit :: nat \ int \ int) (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 \r = LENGTH('a) - 1\ \s = LENGTH('b) - 1\ then have \LENGTH('a) = Suc r\ \LENGTH('b) = Suc s\ \size a = Suc r\ \size b = Suc r\ 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 min.absorb2 simp flip: signed_take_bit_eq_iff_take_bit_eq) done qed lemma bintrunc_id: "\m \ int n; 0 < m\ \ take_bit n m = m" by (simp add: take_bit_int_eq_self_iff le_less_trans less_exp) lemma bin_cat_cong: "concat_bit n b a = concat_bit m d c" if "n = m" "a = c" "take_bit m b = take_bit m d" using that(3) unfolding that(1,2) by (simp add: bin_cat_eq_push_bit_add_take_bit) lemma bin_cat_eqD1: "concat_bit n b a = concat_bit n d c \ a = c" by (metis drop_bit_bin_cat_eq) lemma bin_cat_eqD2: "concat_bit n b a = concat_bit n d c \ take_bit n b = take_bit n d" by (metis take_bit_bin_cat_eq) lemma bin_cat_inj: "(concat_bit n b a) = concat_bit n d c \ a = c \ take_bit n b = take_bit n d" by (auto intro: bin_cat_cong bin_cat_eqD1 bin_cat_eqD2) code_identifier code_module Bits_Int \ (SML) Bit_Operations and (OCaml) Bit_Operations and (Haskell) Bit_Operations and (Scala) Bit_Operations end diff --git a/thys/Word_Lib/Generic_set_bit.thy b/thys/Word_Lib/Generic_set_bit.thy --- a/thys/Word_Lib/Generic_set_bit.thy +++ b/thys/Word_Lib/Generic_set_bit.thy @@ -1,121 +1,123 @@ (* * Copyright Data61, CSIRO (ABN 41 687 119 230) * * SPDX-License-Identifier: BSD-2-Clause *) (* Author: Jeremy Dawson, NICTA *) section \Operation variant for setting and unsetting bits\ theory Generic_set_bit imports "HOL-Library.Word" Most_significant_bit begin class set_bit = semiring_bits + fixes set_bit :: \'a \ nat \ bool \ 'a\ - assumes bit_set_bit_iff [bit_simps]: + assumes bit_set_bit_iff_2n: \bit (set_bit a m b) n \ (if m = n then b else bit a n) \ 2 ^ n \ 0\ +lemmas bit_set_bit_iff[bit_simps] = bit_set_bit_iff_2n[simplified fold_possible_bit simp_thms] + lemma set_bit_eq: \set_bit a n b = (if b then Bit_Operations.set_bit else unset_bit) n a\ for a :: \'a::{ring_bit_operations, set_bit}\ by (rule bit_eqI) (simp add: bit_simps) instantiation int :: set_bit begin definition set_bit_int :: \int \ nat \ bool \ int\ where \set_bit_int i n b = (if b then Bit_Operations.set_bit else Bit_Operations.unset_bit) n i\ instance by standard (simp_all add: set_bit_int_def bit_simps) end instantiation word :: (len) set_bit begin definition set_bit_word :: \'a word \ nat \ bool \ 'a word\ where set_bit_unfold: \set_bit w n b = (if b then Bit_Operations.set_bit n w else unset_bit n w)\ for w :: \'a::len word\ instance by standard (auto simp add: set_bit_unfold bit_simps dest: bit_imp_le_length) end lemma bit_set_bit_word_iff [bit_simps]: \bit (set_bit w m b) n \ (if m = n then n < LENGTH('a) \ b else bit w n)\ for w :: \'a::len word\ by (auto simp add: bit_simps dest: bit_imp_le_length) lemma test_bit_set_gen: "bit (set_bit w n x) m \ (if m = n then n < size w \ x else bit w m)" for w :: "'a::len word" by (simp add: bit_set_bit_word_iff word_size) lemma test_bit_set: "bit (set_bit w n x) n \ n < size w \ x" for w :: "'a::len word" by (auto simp add: bit_simps word_size) lemma word_set_nth: "set_bit w n (bit w n) = w" for w :: "'a::len word" by (rule bit_word_eqI) (simp add: bit_simps) lemma word_set_set_same [simp]: "set_bit (set_bit w n x) n y = set_bit w n y" for w :: "'a::len word" by (rule word_eqI) (simp add : test_bit_set_gen word_size) lemma word_set_set_diff: fixes w :: "'a::len word" assumes "m \ n" shows "set_bit (set_bit w m x) n y = set_bit (set_bit w n y) m x" by (rule word_eqI) (auto simp: test_bit_set_gen word_size assms) lemma word_set_nth_iff: "set_bit w n b = w \ bit w n = b \ n \ size w" for w :: "'a::len word" apply (rule iffI) apply (rule disjCI) apply (drule word_eqD) apply (erule sym [THEN trans]) apply (simp add: test_bit_set) apply (erule disjE) apply clarsimp apply (rule word_eqI) apply (clarsimp simp add : test_bit_set_gen) apply (auto simp add: word_size) apply (rule bit_eqI) apply (simp add: bit_simps) done lemma word_clr_le: "w \ set_bit w n False" for w :: "'a::len word" apply (simp add: set_bit_unfold) apply transfer apply (simp add: take_bit_unset_bit_eq unset_bit_less_eq) done lemma word_set_ge: "w \ set_bit w n True" for w :: "'a::len word" apply (simp add: set_bit_unfold) apply transfer apply (simp add: take_bit_set_bit_eq set_bit_greater_eq) done lemma set_bit_beyond: "size x \ n \ set_bit x n b = x" for x :: "'a :: len word" by (simp add: word_set_nth_iff) lemma one_bit_shiftl: "set_bit 0 n True = push_bit n (1 :: 'a :: len word)" apply (rule word_eqI) apply (auto simp add: word_size bit_simps) done lemmas one_bit_pow = trans [OF one_bit_shiftl push_bit_of_1] end diff --git a/thys/Word_Lib/More_Word.thy b/thys/Word_Lib/More_Word.thy --- a/thys/Word_Lib/More_Word.thy +++ b/thys/Word_Lib/More_Word.thy @@ -1,2550 +1,2543 @@ (* * Copyright Data61, CSIRO (ABN 41 687 119 230) * * SPDX-License-Identifier: BSD-2-Clause *) section \Lemmas on words\ theory More_Word imports "HOL-Library.Word" More_Arithmetic More_Divides begin context includes bit_operations_syntax begin \ \problem posed by TPHOLs referee: criterion for overflow of addition of signed integers\ lemma sofl_test: \sint x + sint y = sint (x + y) \ drop_bit (size x - 1) ((x + y XOR x) AND (x + y XOR y)) = 0\ for x y :: \'a::len word\ proof - obtain n where n: \LENGTH('a) = Suc n\ by (cases \LENGTH('a)\) simp_all have *: \sint x + sint y + 2 ^ Suc n > signed_take_bit n (sint x + sint y) \ sint x + sint y \ - (2 ^ n)\ \signed_take_bit n (sint x + sint y) > sint x + sint y - 2 ^ Suc n \ 2 ^ n > sint x + sint y\ using signed_take_bit_int_greater_eq [of \sint x + sint y\ n] signed_take_bit_int_less_eq [of n \sint x + sint y\] by (auto intro: ccontr) have \sint x + sint y = sint (x + y) \ (sint (x + y) < 0 \ sint x < 0) \ (sint (x + y) < 0 \ sint y < 0)\ using sint_less [of x] sint_greater_eq [of x] sint_less [of y] sint_greater_eq [of y] signed_take_bit_int_eq_self [of \LENGTH('a) - 1\ \sint x + sint y\] apply (auto simp add: not_less) apply (unfold sint_word_ariths) apply (subst signed_take_bit_int_eq_self) prefer 4 apply (subst signed_take_bit_int_eq_self) prefer 7 apply (subst signed_take_bit_int_eq_self) prefer 10 apply (subst signed_take_bit_int_eq_self) apply (auto simp add: signed_take_bit_int_eq_self signed_take_bit_eq_take_bit_minus take_bit_Suc_from_most n not_less intro!: *) apply (smt (z3) take_bit_nonnegative) apply (smt (z3) take_bit_int_less_exp) apply (smt (z3) take_bit_nonnegative) apply (smt (z3) take_bit_int_less_exp) done then show ?thesis apply (simp only: One_nat_def word_size drop_bit_eq_zero_iff_not_bit_last bit_and_iff bit_xor_iff) apply (simp add: bit_last_iff) done qed lemma unat_power_lower [simp]: "unat ((2::'a::len word) ^ n) = 2 ^ n" if "n < LENGTH('a::len)" using that by transfer simp lemma unat_p2: "n < LENGTH('a :: len) \ unat (2 ^ n :: 'a word) = 2 ^ n" by (fact unat_power_lower) lemma word_div_lt_eq_0: "x < y \ x div y = 0" for x :: "'a :: len word" by transfer simp lemma word_div_eq_1_iff: "n div m = 1 \ n \ m \ unat n < 2 * unat (m :: 'a :: len word)" apply (simp only: word_arith_nat_defs word_le_nat_alt word_of_nat_eq_iff flip: nat_div_eq_Suc_0_iff) apply (simp flip: unat_div unsigned_take_bit_eq) done lemma AND_twice [simp]: "(w AND m) AND m = w AND m" by (fact and.right_idem) lemma word_combine_masks: "w AND m = z \ w AND m' = z' \ w AND (m OR m') = (z OR z')" for w m m' z z' :: \'a::len word\ by (simp add: bit.conj_disj_distrib) lemma p2_gt_0: "(0 < (2 ^ n :: 'a :: len word)) = (n < LENGTH('a))" by (simp add : word_gt_0 not_le) lemma uint_2p_alt: \n < LENGTH('a::len) \ uint ((2::'a::len word) ^ n) = 2 ^ n\ using p2_gt_0 [of n, where ?'a = 'a] by (simp add: uint_2p) lemma p2_eq_0: \(2::'a::len word) ^ n = 0 \ LENGTH('a::len) \ n\ by (fact exp_eq_zero_iff) lemma p2len: \(2 :: 'a word) ^ LENGTH('a::len) = 0\ by simp lemma neg_mask_is_div: "w AND NOT (mask n) = (w div 2^n) * 2^n" for w :: \'a::len word\ by (rule bit_word_eqI) (auto simp add: bit_simps simp flip: push_bit_eq_mult drop_bit_eq_div) lemma neg_mask_is_div': "n < size w \ w AND NOT (mask n) = ((w div (2 ^ n)) * (2 ^ n))" for w :: \'a::len word\ by (rule neg_mask_is_div) lemma and_mask_arith: "w AND mask n = (w * 2^(size w - n)) div 2^(size w - n)" for w :: \'a::len word\ by (rule bit_word_eqI) (auto simp add: bit_simps word_size simp flip: push_bit_eq_mult drop_bit_eq_div) lemma and_mask_arith': "0 < n \ w AND mask n = (w * 2^(size w - n)) div 2^(size w - n)" for w :: \'a::len word\ by (rule and_mask_arith) 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 :: \'a::len word\ by (simp add: mask_eq_decr_exp) lemma word_and_mask_le_2pm1: "w AND mask n \ 2 ^ n - 1" for w :: \'a::len word\ by (simp add: mask_2pm1[symmetric] word_and_le1) lemma is_aligned_AND_less_0: "u AND mask n = 0 \ v < 2^n \ u AND v = 0" for u v :: \'a::len word\ apply (drule less_mask_eq) apply (simp flip: take_bit_eq_mask) apply (simp add: bit_eq_iff) apply (auto simp add: bit_simps) done lemma and_mask_eq_iff_le_mask: \w AND mask n = w \ w \ mask n\ for w :: \'a::len word\ apply (simp flip: take_bit_eq_mask) apply (cases \n \ LENGTH('a)\; transfer) apply (simp_all add: not_le min_def) apply (simp_all add: mask_eq_exp_minus_1) apply auto apply (metis take_bit_int_less_exp) apply (metis min_def nat_less_le take_bit_int_eq_self_iff take_bit_take_bit) done lemma less_eq_mask_iff_take_bit_eq_self: \w \ mask n \ take_bit n w = w\ for w :: \'a::len word\ by (simp add: and_mask_eq_iff_le_mask take_bit_eq_mask) 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 \ x - 1) = (y < x))" by uint_arith lemma gt0_iff_gem1: \0 < x \ x - 1 < x\ for x :: \'a::len word\ by (metis add.right_neutral diff_add_cancel less_irrefl measure_unat unat_arith_simps(2) word_neq_0_conv word_sub_less_iff) lemma power_2_ge_iff: \2 ^ n - (1 :: 'a::len word) < 2 ^ n \ n < LENGTH('a)\ using gt0_iff_gem1 p2_gt_0 by blast lemma le_mask_iff_lt_2n: "n < len_of TYPE ('a) = (((w :: 'a :: len word) \ mask n) = (w < 2 ^ n))" unfolding mask_2pm1 by (rule trans [OF p2_gt_0 [THEN sym] le_m1_iff_lt]) lemma mask_lt_2pn: \n < LENGTH('a) \ mask n < (2 :: 'a::len word) ^ n\ by (simp add: mask_eq_exp_minus_1 power_2_ge_iff) 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 \ 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 word_and_max_word: fixes a::"'a::len word" shows "x = - 1 \ a AND x = a" by simp lemma word_and_full_mask_simp: \x AND mask LENGTH('a) = x\ for x :: \'a::len word\ -proof (rule bit_eqI) - fix n - assume \2 ^ n \ (0 :: 'a word)\ - then have \n < LENGTH('a)\ - by simp - then show \bit (x AND Bit_Operations.mask LENGTH('a)) n \ bit x n\ - by (simp add: bit_and_iff bit_mask_iff) -qed + by (simp add: bit_eq_iff bit_simps) lemma of_int_uint: "of_int (uint x) = x" by (fact word_of_int_uint) corollary word_plus_and_or_coroll: "x AND y = 0 \ x + y = x OR y" for x y :: \'a::len word\ using word_plus_and_or[where x=x and y=y] by simp corollary word_plus_and_or_coroll2: "(x AND w) + (x AND NOT w) = x" for x w :: \'a::len word\ apply (subst disjunctive_add) apply (simp add: bit_simps) apply (simp flip: bit.conj_disj_distrib) done lemma nat_mask_eq: \nat (mask n) = mask n\ by (simp add: nat_eq_iff of_nat_mask_eq) lemma unat_mask_eq: \unat (mask n :: 'a::len word) = mask (min LENGTH('a) n)\ by transfer (simp add: nat_mask_eq) lemma word_plus_mono_left: fixes x :: "'a :: len word" shows "\y \ z; x \ x + z\ \ y + x \ z + x" by unat_arith lemma less_Suc_unat_less_bound: "n < Suc (unat (x :: 'a :: len word)) \ n < 2 ^ LENGTH('a)" by (auto elim!: order_less_le_trans intro: Suc_leI) lemma up_ucast_inj: "\ ucast x = (ucast y::'b::len word); LENGTH('a) \ len_of TYPE ('b) \ \ x = (y::'a::len word)" by transfer (simp add: min_def split: if_splits) lemmas ucast_up_inj = up_ucast_inj lemma up_ucast_inj_eq: "LENGTH('a) \ len_of TYPE ('b) \ (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 \ x \ x + y" by (metis diff_minus_eq_add less_imp_le sub_wrap_lt) lemma ucast_ucast_eq: "\ ucast x = (ucast (ucast y::'a word)::'c::len word); LENGTH('a) \ LENGTH('b); LENGTH('b) \ LENGTH('c) \ \ x = ucast y" for x :: "'a::len word" and y :: "'b::len word" apply transfer apply (cases \LENGTH('c) = LENGTH('a)\) apply (auto simp add: min_def) done lemma ucast_0_I: "x = 0 \ ucast x = 0" by simp 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 \ 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 word_less_power_trans2: fixes n :: "'a::len word" shows "\n < 2 ^ (m - k); k \ m; m < LENGTH('a)\ \ n * 2 ^ k < 2 ^ m" by (subst field_simps, rule word_less_power_trans) lemma Suc_unat_diff_1: fixes x :: "'a :: len word" assumes lt: "1 \ 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_eq_unatI: \v = w\ if \unat v = unat w\ using that by transfer (simp add: nat_eq_iff) lemma word_div_sub: fixes x :: "'a :: len word" assumes yx: "y \ x" and y0: "0 < y" shows "(x - y) div y = x div y - 1" apply (rule word_eq_unatI) 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 \ 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 "\ = ((2 ^ us - 1) + 2 ^ sz) div 2 ^ us" using szv by (simp add: unat_minus_one) also have "\ = 2 ^ q + ((2 ^ us - 1) div 2 ^ us)" apply (subst qv) apply (subst power_add) apply (subst div_mult_self2; simp) done also have "\ = 2 ^ (sz - us)" using qv by simp finally show ?thesis .. qed lemma enum_word_nth_eq: \(Enum.enum :: 'a::len word list) ! n = word_of_nat n\ if \n < 2 ^ LENGTH('a)\ for n using that by (simp add: enum_word_def) lemma length_enum_word_eq: \length (Enum.enum :: 'a::len word list) = 2 ^ LENGTH('a)\ by (simp add: enum_word_def) lemma unat_lt2p [iff]: \unat x < 2 ^ LENGTH('a)\ for x :: \'a::len word\ by transfer simp lemma of_nat_unat [simp]: "of_nat \ unat = id" by (rule ext, simp) lemma Suc_unat_minus_one [simp]: "x \ 0 \ 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 \ 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_le_nat_alt iffD1 [OF unat_add_lem] elim: add_le_mono1) lemma word_add_le_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_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 "\i \ j; unat j + unat k < 2 ^ LENGTH('a)\ \ k + i \ 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 \ j + k) = (i \ j)" proof assume "i \ j" show "i + k \ j + k" by (rule word_add_le_mono1) fact+ next assume "i + k \ j + k" show "i \ 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 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 "\k \ n; n \ m\ \ n - k \ m" by (auto simp: unat_sub word_le_nat_alt) lemma word_less_imp_diff_less: fixes n :: "'a::len word" shows "\k \ n; n < m\ \ 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 \ 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 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 \ j * k) = (i \ j)" proof assume "i \ j" show "i * k \ j * k" by (rule word_mult_le_mono1) fact+ next assume p: "i * k \ j * k" have "0 < unat k" using knz by (simp add: word_less_nat_alt) then show "i \ 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 "\0 < n; 0 < m; n \ m\ \ 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 word_add_increasing: fixes x :: "'a :: len word" shows "\ p + w \ x; p \ p + w \ \ p \ x" by unat_arith lemma word_random: fixes x :: "'a :: len word" shows "\ p \ p + x'; x \ x' \ \ p \ p + x" by unat_arith lemma word_sub_mono: "\ a \ c; d \ b; a - b \ a; c - d \ c \ \ (a - b) \ (c - d :: 'a :: len word)" by unat_arith lemma power_not_zero: "n < LENGTH('a::len) \ (2 :: 'a word) ^ n \ 0" by (metis p2_gt_0 word_neq_0_conv) lemma word_gt_a_gt_0: "a < n \ (0 :: 'a::len word) < n" apply (case_tac "n = 0") apply clarsimp apply (clarsimp simp: word_neq_0_conv) done lemma word_power_less_1 [simp]: "sz < LENGTH('a::len) \ (2::'a word) ^ sz - 1 < 2 ^ sz" apply (simp add: word_less_nat_alt) apply (subst unat_minus_one) apply simp_all done lemma word_sub_1_le: "x \ 0 \ x - 1 \ (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 push_bit_word_eq_nonzero: \push_bit n w \ 0\ if \w < 2 ^ m\ \m + n < LENGTH('a)\ \w \ 0\ for w :: \'a::len word\ using that apply (simp only: word_neq_0_conv word_less_nat_alt mod_0 unat_word_ariths unat_power_lower word_le_nat_alt) apply (metis add_diff_cancel_right' gr0I gr_implies_not0 less_or_eq_imp_le min_def push_bit_eq_0_iff take_bit_nat_eq_self_iff take_bit_push_bit take_bit_take_bit unsigned_push_bit_eq) done 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 \sz < LENGTH('a)\) 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 word_plus_mcs_4: "\v + x \ w + x; x \ v + x\ \ v \ (w::'a::len word)" by uint_arith lemma word_plus_mcs_3: "\v \ w; x \ w + x\ \ v + x \ w + (x::'a::len word)" by unat_arith lemma word_le_minus_one_leq: "x < y \ x \ y - 1" for x :: "'a :: len word" by transfer (metis le_less_trans less_irrefl take_bit_decr_eq take_bit_nonnegative zle_diff1_eq) lemma word_less_sub_le[simp]: fixes x :: "'a :: len word" assumes nv: "n < LENGTH('a)" shows "(x \ 2 ^ n - 1) = (x < 2 ^ n)" using le_less_trans word_le_minus_one_leq nv power_2_ge_iff by blast lemma unat_of_nat_len: "x < 2 ^ LENGTH('a) \ unat (of_nat x :: 'a::len word) = x" by (simp add: take_bit_nat_eq_self_iff) lemma unat_of_nat_eq: "x < 2 ^ LENGTH('a) \ unat (of_nat x ::'a::len word) = x" by (rule unat_of_nat_len) lemma unat_eq_of_nat: "n < 2 ^ LENGTH('a) \ (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 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 \ x" and sz: "n < LENGTH('a)" and anz: "a mod 2 ^ n \ 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 \ 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 "\ \ 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 "\ \ 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 mask_out_sub_mask: "(x AND NOT (mask n)) = x - (x AND (mask n))" for x :: \'a::len word\ by (simp add: field_simps word_plus_and_or_coroll2) lemma subtract_mask: "p - (p AND mask n) = (p AND NOT (mask n))" "p - (p AND NOT (mask n)) = (p AND mask n)" for p :: \'a::len word\ by (simp add: field_simps word_plus_and_or_coroll2)+ lemma take_bit_word_eq_self_iff: \take_bit n w = w \ n \ LENGTH('a) \ w < 2 ^ n\ for w :: \'a::len word\ using take_bit_int_eq_self_iff [of n \take_bit LENGTH('a) (uint w)\] by (transfer fixing: n) auto lemma word_power_increasing: assumes x: "2 ^ x < (2 ^ y::'a::len word)" "x < LENGTH('a::len)" "y < LENGTH('a::len)" shows "x < y" using x using assms by transfer simp lemma mask_twice: "(x AND mask n) AND mask m = x AND mask (min m n)" for x :: \'a::len word\ by (simp flip: take_bit_eq_mask) lemma plus_one_helper[elim!]: "x < n + (1 :: 'a :: len word) \ x \ n" apply (simp add: word_less_nat_alt word_le_nat_alt field_simps) apply (case_tac "1 + n = 0") apply simp_all apply (subst(asm) unatSuc, assumption) apply arith done lemma plus_one_helper2: "\ x \ n; n + 1 \ 0 \ \ 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 \ - 1 \ (y < (x + 1)) = (y < x \ 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 \ - 1 \ x < k + 1 \ x \ k" using less_x_plus_1 word_le_less_eq by auto lemma word_Suc_le: fixes k::"'a::len word" shows "x \ - 1 \ x + 1 \ k \ x < k" by (meson not_less word_Suc_leq) lemma word_lessThan_Suc_atMost: \{..< k + 1} = {..k}\ if \k \ - 1\ for k :: \'a::len word\ using that by (simp add: lessThan_def atMost_def word_Suc_leq) lemma word_atLeastLessThan_Suc_atLeastAtMost: \{l ..< u + 1} = {l..u}\ if \u \ - 1\ for l :: \'a::len word\ using that by (simp add: atLeastAtMost_def atLeastLessThan_def word_lessThan_Suc_atMost) lemma word_atLeastAtMost_Suc_greaterThanAtMost: \{m<..u} = {m + 1..u}\ if \m \ - 1\ for m :: \'a::len word\ 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 \ - 1" and "l \ m" and "m \ u" shows "{l..m} \ {m+1..u} = {l..u}" proof - from ivl_disj_un_two(8)[OF assms(2) assms(3)] have "{l..u} = {l..m} \ {m<..u}" by blast with assms show ?thesis by(simp add: word_atLeastAtMost_Suc_greaterThanAtMost) qed lemma max_word_less_eq_iff [simp]: \- 1 \ w \ w = - 1\ for w :: \'a::len word\ by (fact word_order.extremum_unique) lemma word_or_zero: "(a OR b = 0) = (a = 0 \ b = 0)" for a b :: \'a::len word\ by (fact or_eq_0_iff) lemma word_2p_mult_inc: assumes x: "2 * 2 ^ n < (2::'a::len word) * 2 ^ m" assumes suc_n: "Suc n < LENGTH('a::len)" shows "2^n < (2::'a::len word)^m" by (smt suc_n le_less_trans lessI nat_less_le nat_mult_less_cancel_disj p2_gt_0 power_Suc power_Suc unat_power_lower word_less_nat_alt x) lemma power_overflow: "n \ LENGTH('a) \ 2 ^ n = (0 :: 'a::len word)" by simp 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 word_sint_1: "sint (1::'a::len word) = (if LENGTH('a) = 1 then -1 else 1)" by (fact signed_1) lemma ucast_of_nat: "is_down (ucast :: 'a :: len word \ 'b :: len word) \ ucast (of_nat n :: 'a word) = (of_nat n :: 'b word)" by transfer simp lemma scast_1': "(scast (1::'a::len word) :: 'b::len word) = (word_of_int (signed_take_bit (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 unat_minus_one_word: "unat (-1 :: 'a :: len word) = 2 ^ LENGTH('a) - 1" apply (simp only: flip: mask_eq_exp_minus_1) apply transfer apply (simp add: take_bit_minus_one_eq_mask nat_mask_eq) 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 two_power_increasing: "\ n \ m; m < LENGTH('a) \ \ (2 :: 'a :: len word) ^ n \ 2 ^ m" by (simp add: word_le_nat_alt) lemma word_leq_le_minus_one: "\ x \ y; x \ 0 \ \ 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 neg_mask_combine: "NOT(mask a) AND NOT(mask b) = NOT(mask (max a b) :: 'a::len word)" by (rule bit_word_eqI) (auto simp add: bit_simps) lemma neg_mask_twice: "x AND NOT(mask n) AND NOT(mask m) = x AND NOT(mask (max n m))" for x :: \'a::len word\ by (rule bit_word_eqI) (auto simp add: bit_simps) lemma multiple_mask_trivia: "n \ m \ (x AND NOT(mask n)) + (x AND mask n AND NOT(mask m)) = x AND NOT(mask m)" for x :: \'a::len word\ 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 word_of_nat_less: "\ n < unat x \ \ 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 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 mask_over_length: "LENGTH('a) \ n \ mask n = (-1::'a::len word)" by (simp add: mask_eq_decr_exp) lemma Suc_2p_unat_mask: "n < LENGTH('a) \ Suc (2 ^ n * k + unat (mask n :: 'a::len word)) = 2 ^ n * (k+1)" by (simp add: unat_mask) lemma sint_of_nat_ge_zero: "x < 2 ^ (LENGTH('a) - 1) \ sint (of_nat x :: 'a :: len word) \ 0" by (simp add: bit_iff_odd) lemma int_eq_sint: "x < 2 ^ (LENGTH('a) - 1) \ sint (of_nat x :: 'a :: len word) = int x" apply transfer apply (rule signed_take_bit_int_eq_self) apply simp_all apply (metis negative_zle numeral_power_eq_of_nat_cancel_iff) done lemma sint_of_nat_le: "\ b < 2 ^ (LENGTH('a) - 1); a \ b \ \ sint (of_nat a :: 'a :: len word) \ sint (of_nat b :: 'a :: len word)" apply (cases \LENGTH('a)\) apply simp_all apply transfer apply (subst signed_take_bit_eq_if_positive) apply (simp add: bit_simps) apply (metis bit_take_bit_iff nat_less_le order_less_le_trans take_bit_nat_eq_self_iff) apply (subst signed_take_bit_eq_if_positive) apply (simp add: bit_simps) apply (metis bit_take_bit_iff nat_less_le take_bit_nat_eq_self_iff) apply (simp flip: of_nat_take_bit add: take_bit_nat_eq_self) done lemma word_le_not_less: "((b::'a::len word) \ a) = (\(a < b))" by fastforce lemma less_is_non_zero_p1: fixes a :: "'a :: len word" shows "a < k \ a + 1 \ 0" apply (erule contrapos_pn) apply (drule max_word_wrap) apply (simp add: not_less) done lemma unat_add_lem': "(unat x + unat y < 2 ^ LENGTH('a)) \ (unat (x + y :: 'a :: len word) = unat x + unat y)" by (subst unat_add_lem[symmetric], assumption) lemma word_less_two_pow_divI: "\ (x :: 'a::len word) < 2 ^ (n - m); m \ n; n < LENGTH('a) \ \ 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: "\ (x :: 'a::len word) < 2 ^ n div 2 ^ m \ \ n \ m \ (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: "\ n < LENGTH('a) \ \ {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 ucast_less: "LENGTH('b) < LENGTH('a) \ (ucast (x :: 'b :: len word) :: ('a :: len word)) < 2 ^ LENGTH('b)" by transfer simp lemma ucast_range_less: "LENGTH('a :: len) < LENGTH('b :: len) \ range (ucast :: 'a word \ '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) apply (rule bit_word_eqI) apply (auto simp add: bit_simps) apply (metis bit_take_bit_iff less_mask_eq not_less take_bit_eq_mask) done lemma word_power_less_diff: "\2 ^ n * q < (2::'a::len word) ^ m; q < 2 ^ (LENGTH('a) - n)\ \ q < 2 ^ (m - n)" apply (case_tac "m \ LENGTH('a)") apply (simp add: power_overflow) apply (case_tac "n \ 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 lemma word_less_sub_1: "x < (y :: 'a :: len word) \ x \ y - 1" by (fact word_le_minus_one_leq) lemma word_sub_mono2: "\ a + b \ c + d; c \ a; b \ a + b; d \ c + d \ \ b \ (d :: 'a :: len word)" apply (drule(1) word_sub_mono) apply simp apply simp apply simp done lemma word_not_le: "(\ x \ (y :: 'a :: len word)) = (y < x)" by fastforce lemma word_subset_less: "\ {x .. x + r - 1} \ {y .. y + s - 1}; x \ x + r - 1; y \ y + (s :: 'a :: len word) - 1; s \ 0 \ \ r \ 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) \ uint (2 ^ n :: 'a :: len word) = (2 ^ n :: int)" by (rule uint_2p_alt) lemma power_le_mono: "\2 ^ n \ (2::'a::len word) ^ m; n < LENGTH('a); m < LENGTH('a)\ \ n \ 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 two_power_eq: "\n < LENGTH('a); m < LENGTH('a)\ \ ((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 unat_less_helper: "x < of_nat n \ 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 \ x < y \ 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: "\of_nat n = (0::'a::len word); n < 2 ^ LENGTH('a)\ \ n = 0" by transfer (simp add: take_bit_eq_mod) lemma of_nat_inj: "\x < 2 ^ LENGTH('a); y < 2 ^ LENGTH('a)\ \ (of_nat x = (of_nat y :: 'a :: len word)) = (x = y)" by (metis unat_of_nat_len) lemma div_to_mult_word_lt: "\ (x :: 'a :: len word) \ y div z \ \ x * z \ 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 ucast_ucast_mask: "(ucast :: 'a :: len word \ 'b :: len word) (ucast x) = x AND mask (len_of TYPE ('a))" apply (simp flip: take_bit_eq_mask) apply transfer apply (simp add: ac_simps) done lemma ucast_ucast_len: "\ x < 2 ^ LENGTH('b) \ \ 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) \ 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 \2 ^ LENGTH('a) = nat (2 ^ LENGTH('a))\ by simp moreover have \unat (ucast x :: 'a word) = unat x mod nat (2 ^ LENGTH('a))\ by transfer (simp flip: nat_mod_distrib take_bit_eq_mod) ultimately show ?thesis by (simp only:) qed lemma ucast_less_ucast: "LENGTH('a) \ LENGTH('b) \ (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 \ \This weaker version was previously called @{text ucast_less_ucast}. We retain it to support existing proofs.\ lemmas ucast_less_ucast_weak = ucast_less_ucast[OF order.strict_implies_order] lemma unat_Suc2: fixes n :: "'a :: len word" shows "n \ -1 \ unat (n + 1) = Suc (unat n)" apply (subst add.commute, rule unatSuc) apply (subst eq_diff_eq[symmetric], simp add: minus_equation_iff) done lemma word_div_1: "(n :: 'a :: len word) div 1 = n" by (fact bits_div_by_1) lemma word_minus_one_le: "-1 \ (x :: 'a :: len word) = (x = -1)" by (fact word_order.extremum_unique) lemma up_scast_inj: "\ scast x = (scast y :: 'b :: len word); size x \ LENGTH('b) \ \ x = y" apply transfer apply (cases \LENGTH('a)\) apply simp_all apply (metis order_refl take_bit_signed_take_bit take_bit_tightened) done lemma up_scast_inj_eq: "LENGTH('a) \ len_of TYPE ('b) \ (scast x = (scast y::'b::len word)) = (x = (y::'a::len word))" by (fastforce dest: up_scast_inj simp: word_size) lemma word_le_add: fixes x :: "'a :: len word" shows "x \ y \ \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 "\x + v \ x + w; x \ x + v\ \ v \ w" apply (rule word_plus_mcs_4) apply (simp add: add.commute) apply (simp add: add.commute) done lemma unat_eq_1: \unat x = Suc 0 \ x = 1\ by (auto intro!: unsigned_word_eqI [where ?'a = nat]) lemma word_unat_Rep_inject1: \unat x = unat 1 \ x = 1\ by (simp add: unat_eq_1) lemma and_not_mask_twice: "(w AND NOT (mask n)) AND NOT (mask m) = w AND NOT (mask (max m n))" for w :: \'a::len word\ by (rule bit_word_eqI) (auto simp add: bit_simps) lemma word_less_cases: "x < y \ x = y - 1 \ x < y - (1 ::'a::len word)" apply (drule word_less_sub_1) apply (drule order_le_imp_less_or_eq) apply auto done lemma mask_and_mask: "mask a AND mask b = (mask (min a b) :: 'a::len word)" by (simp flip: take_bit_eq_mask ac_simps) lemma mask_eq_0_eq_x: "(x AND w = 0) = (x AND NOT w = x)" for x w :: \'a::len word\ using word_plus_and_or_coroll2[where x=x and w=w] by auto lemma mask_eq_x_eq_0: "(x AND w = x) = (x AND NOT w = 0)" for x w :: \'a::len word\ using word_plus_and_or_coroll2[where x=x and w=w] by auto lemma compl_of_1: "NOT 1 = (-2 :: 'a :: len word)" by (fact not_one_eq) lemma split_word_eq_on_mask: "(x = y) = (x AND m = y AND m \ x AND NOT m = y AND NOT m)" for x y m :: \'a::len word\ apply transfer apply (simp add: bit_eq_iff) apply (auto simp add: bit_simps ac_simps) done 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) \ ucast (of_nat x :: 'a :: len word) = (of_nat x :: 'b :: len word)" apply transfer apply (auto simp add: take_bit_of_nat min_def not_le) apply (metis linorder_not_less min_def take_bit_nat_eq_self take_bit_take_bit) done lemma word_le_make_less: fixes x :: "'a :: len word" shows "y \ -1 \ (x \ 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 word_leq_minus_one_le: fixes x :: "'a::len word" shows "\y \ 0; x \ y - 1 \ \ x < y" using le_m1_iff_lt word_neq_0_conv by blast lemma word_count_from_top: "n \ 0 \ {0 ..< n :: 'a :: len word} = {0 ..< n - 1} \ {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: "\ x - 1 < y \ \ x \ (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 word_div_less: "m < n \ m div n = 0" for m :: "'a :: len word" by (simp add: unat_mono word_arith_nat_defs(6)) lemma word_must_wrap: "\ x \ n - 1; n \ x \ \ n = (0 :: 'a :: len word)" using dual_order.trans sub_wrap word_less_1 by blast lemma range_subset_card: "\ {a :: 'a :: len word .. b} \ {c .. d}; b \ a \ \ d \ c \ d - c \ b - a" using word_sub_le word_sub_mono by fastforce lemma less_1_simp: "n - 1 < m = (n \ (m :: 'a :: len word) \ n \ 0)" by unat_arith lemma word_power_mod_div: fixes x :: "'a::len word" shows "\ n < LENGTH('a); m < LENGTH('a)\ \ 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 \ 0 \ {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 \ 0 \ {a..b - 1} = {a.. 'b :: len word) x" by transfer simp lemma overflow_plus_one_self: "(1 + p \ 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="\x. x - 1"]) apply simp apply (simp add: field_simps) apply simp done lemma plus_1_less: "(x + 1 \ (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="\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 word_plus_strict_mono_right: fixes x :: "'a :: len word" shows "\y < z; x \ x + z\ \ x + y < x + z" by unat_arith lemma word_div_mult: "0 < c \ a < b * c \ 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 \auto simp add: word_less_nat_alt word_le_nat_alt unat_div\) lemma word_less_power_trans_ofnat: "\n < 2 ^ (m - k); k \ m; m < LENGTH('a)\ \ 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) \ (1 :: 'a :: len word) \ 2 ^ n" by (rule inc_le[where i=0, simplified], erule iffD2[OF p2_gt_0]) lemma unat_1_0: "1 \ (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 "\LENGTH('a) \ 1; x < 2\ \ x = 0 \ x = 1" apply (cases \2 \ LENGTH('a)\) 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 "\ p < 2 ^ x; x < len_of TYPE ('a) \ \ 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 del: of_nat_power) done lemma of_nat_n_less_equal_power_2: "n < LENGTH('a::len) \ ((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 AND 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 of_nat_mono_maybe_le: "\x < 2 ^ LENGTH('a); y < 2 ^ LENGTH('a)\ \ (y \ x) = ((of_nat y :: 'a :: len word) \ of_nat x)" apply (clarsimp simp: le_less) apply (rule disj_cong) apply (rule of_nat_mono_maybe', assumption+) apply auto using of_nat_inj apply blast done lemma mask_AND_NOT_mask: "(w AND NOT (mask n)) AND mask n = 0" for w :: \'a::len word\ by (rule bit_word_eqI) (simp add: bit_simps) lemma AND_NOT_mask_plus_AND_mask_eq: "(w AND NOT (mask n)) + (w AND mask n) = w" for w :: \'a::len word\ apply (subst disjunctive_add) apply (auto simp add: bit_simps) apply (rule bit_word_eqI) apply (auto simp add: bit_simps) done lemma mask_eqI: fixes x :: "'a :: len word" assumes m1: "x AND mask n = y AND mask n" and m2: "x AND NOT (mask n) = y AND NOT (mask n)" shows "x = y" proof - have *: \x = x AND mask n OR x AND NOT (mask n)\ for x :: \'a word\ by (rule bit_word_eqI) (auto simp add: bit_simps) from assms * [of x] * [of y] show ?thesis by simp qed lemma neq_0_no_wrap: fixes x :: "'a :: len word" shows "\ x \ x + y; x \ 0 \ \ x + y \ 0" by clarsimp lemma unatSuc2: fixes n :: "'a :: len word" shows "n + 1 \ 0 \ unat (n + 1) = Suc (unat n)" by (simp add: add.commute unatSuc) lemma word_of_nat_le: "n \ unat x \ of_nat n \ 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 \ of_nat b \ unat a \ b" by (metis eq_iff le_cases le_unat_uoi word_of_nat_le) lemma mask_Suc_0 : "mask (Suc 0) = (1 :: 'a::len word)" by (simp add: mask_eq_decr_exp) lemma bool_mask': fixes x :: "'a :: len word" shows "2 < LENGTH('a) \ (0 < x AND 1) = (x AND 1 = 1)" by (simp add: and_one_eq mod_2_eq_odd) lemma ucast_ucast_add: fixes x :: "'a :: len word" fixes y :: "'b :: len word" shows "LENGTH('b) \ LENGTH('a) \ ucast (ucast x + y) = x + ucast y" apply transfer apply simp apply (subst (2) take_bit_add [symmetric]) apply (subst take_bit_add [symmetric]) apply simp done lemma lt1_neq0: fixes x :: "'a :: len word" shows "(1 \ x) = (x \ 0)" by unat_arith lemma word_plus_one_nonzero: fixes x :: "'a :: len word" shows "\x \ x + y; y \ 0\ \ x + 1 \ 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 "\n' \ n; n' \ 0\ \ (n - n') + 1 \ 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 "\ z \ y; y \ x; z \ x \ \ x - y \ x - z" apply (rule word_sub_mono) apply simp apply assumption apply (erule word_sub_le) apply (erule word_sub_le) done lemma word_0_sle_from_less: \0 \s x\ if \x < 2 ^ (LENGTH('a) - 1)\ for x :: \'a::len word\ using that apply transfer apply (cases \LENGTH('a)\) apply simp_all apply (metis bit_take_bit_iff min_def nat_less_le not_less_eq take_bit_int_eq_self_iff take_bit_take_bit) done lemma ucast_sub_ucast: fixes x :: "'a::len word" assumes "y \ x" assumes T: "LENGTH('a) \ 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: "\a + (1::('a::len) word) \ b; a < of_nat x\ \ 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:"\ a < b; unat b = c \ \ a < of_nat c" by fastforce lemma word_le_plus_1: "\ (y::('a::len) word) < y + n; a < n \ \ y + a \ y + a + 1" by unat_arith lemma word_le_plus:"\(a::('a::len) word) < a + b; c < b\ \ a \ a + c" by (metis order_less_imp_le word_random) lemma sint_minus1 [simp]: "(sint x = -1) = (x = -1)" apply (cases \LENGTH('a)\) apply simp_all apply transfer apply (simp flip: signed_take_bit_eq_iff_take_bit_eq) done lemma sint_0 [simp]: "(sint x = 0) = (x = 0)" by (fact signed_eq_0_iff) (* 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 \\ len_of TYPE ('a::len) = 1; (a::'a word) = 0; sint a = 0 \ \ P\ \\ len_of TYPE ('a) = 1; a = 1; sint (1 :: 'a word) = -1 \ \ P\ \\ len_of TYPE ('a) > 1; sint (1 :: 'a word) = 1 \ \ P\ proof (cases \LENGTH('a) = 1\) case True then have \a = 0 \ a = 1\ 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 (cases \LENGTH('a)\) apply simp_all apply transfer apply (simp add: signed_take_bit_int_eq_self) done lemma sint_int_max_plus_1: "sint (2 ^ (LENGTH('a) - Suc 0) :: ('a::len) word) = - (2 ^ (LENGTH('a) - Suc 0))" apply (cases \LENGTH('a)\) apply simp_all apply (subst word_of_int_2p [symmetric]) apply (subst int_word_sint) apply simp done lemma uint_range': \0 \ uint x \ uint x < 2 ^ LENGTH('a)\ for x :: \'a::len word\ by transfer simp lemma sint_of_int_eq: "\ - (2 ^ (LENGTH('a) - 1)) \ x; x < 2 ^ (LENGTH('a) - 1) \ \ 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 sint_ucast_eq_uint: "\ \ is_down (ucast :: ('a::len word \ 'b::len word)) \ \ sint ((ucast :: ('a::len word \ 'b::len word)) x) = uint x" apply transfer apply (simp add: signed_take_bit_take_bit) done lemma word_less_nowrapI': "(x :: 'a :: len word) \ z - k \ k \ z \ 0 < k \ 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 \ 'a word) \ unat (ucast x :: ('a::len) word) = unat (x :: ('b::len) word)" unfolding ucast_eq unat_eq_nat_uint apply transfer apply simp done lemma ucast_mono: "\ (x :: 'b :: len word) < y; y < 2 ^ LENGTH('a) \ \ 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 apply (simp add: word_less_nat_alt) done lemma ucast_mono_le: "\x \ y; y < 2 ^ LENGTH('b)\ \ (ucast (x :: 'a :: len word) :: 'b :: len word) \ ucast y" apply (simp only: flip: ucast_nat_def) apply (subst of_nat_mono_maybe_le[symmetric]) apply (rule unat_less_helper) apply simp apply (rule unat_less_helper) apply (erule le_less_trans) apply (simp_all add: word_le_nat_alt) done lemma ucast_mono_le': "\ unat y < 2 ^ LENGTH('b); LENGTH('b::len) < LENGTH('a::len); x \ y \ \ ucast x \ (ucast y :: 'b word)" for x y :: \'a::len word\ by (auto simp: word_less_nat_alt intro: ucast_mono_le) lemma neg_mask_add_mask: "((x:: 'a :: len word) AND NOT (mask n)) + (2 ^ n - 1) = x OR mask n" unfolding mask_2pm1 [symmetric] apply (subst word_plus_and_or_coroll; rule bit_word_eqI) apply (auto simp add: bit_simps) done lemma le_step_down_word:"\(i::('a::len) word) \ n; i = n \ P; i \ n - 1 \ P\ \ P" by unat_arith lemma le_step_down_word_2: fixes x :: "'a::len word" shows "\x \ y; x \ y\ \ x \ y - 1" by (subst (asm) word_le_less_eq, clarsimp, simp add: word_le_minus_one_leq) lemma NOT_mask_AND_mask[simp]: "(w AND mask n) AND NOT (mask n) = 0" by (rule bit_eqI) (simp add: bit_simps) lemma and_and_not[simp]:"(a AND b) AND NOT b = 0" for a b :: \'a::len word\ apply (subst word_bw_assocs(1)) apply clarsimp done lemma ex_mask_1[simp]: "(\x. mask x = (1 :: 'a::len word))" apply (rule_tac x=1 in exI) apply (simp add:mask_eq_decr_exp) done lemma not_switch:"NOT a = x \ a = NOT x" by auto lemma test_bit_eq_iff: "bit u = bit v \ u = v" for u v :: "'a::len word" - by (simp add: bit_eq_iff fun_eq_iff) + by (auto intro: bit_eqI simp add: fun_eq_iff) lemma test_bit_size: "bit w n \ n < size w" for w :: "'a::len word" by transfer simp lemma word_eq_iff: "x = y \ (\n?P \ ?Q\) for x y :: "'a::len word" by transfer (auto simp add: bit_eq_iff bit_take_bit_iff) lemma word_eqI: "(\n. n < size u \ bit u n = bit v n) \ u = v" for u :: "'a::len word" by (simp add: word_size word_eq_iff) lemma word_eqD: "u = v \ bit u x = bit v x" for u v :: "'a::len word" by simp lemma test_bit_bin': "bit w n \ n < size w \ bit (uint w) n" by transfer (simp add: bit_take_bit_iff) lemmas test_bit_bin = test_bit_bin' [unfolded word_size] lemma word_test_bit_def: \bit a = bit (uint a)\ by transfer (simp add: fun_eq_iff bit_take_bit_iff) lemmas test_bit_def' = word_test_bit_def [THEN fun_cong] lemma word_test_bit_transfer [transfer_rule]: "(rel_fun pcr_word (rel_fun (=) (=))) (\x n. n < LENGTH('a) \ bit x n) (bit :: 'a::len word \ _)" by transfer_prover lemma test_bit_wi: "bit (word_of_int x :: 'a::len word) n \ n < LENGTH('a) \ bit x n" by transfer simp lemma word_ops_nth_size: "n < size x \ bit (x OR y) n = (bit x n | bit y n) \ bit (x AND y) n = (bit x n \ bit y n) \ bit (x XOR y) n = (bit x n \ bit y n) \ bit (NOT x) n = (\ bit x n)" for x :: "'a::len word" by transfer (simp add: bit_or_iff bit_and_iff bit_xor_iff bit_not_iff) lemma word_ao_nth: "bit (x OR y) n = (bit x n | bit y n) \ bit (x AND y) n = (bit x n \ bit y n)" for x :: "'a::len word" by transfer (auto simp add: bit_or_iff bit_and_iff) lemmas lsb0 = len_gt_0 [THEN word_ops_nth_size [unfolded word_size]] lemma nth_sint: fixes w :: "'a::len word" defines "l \ LENGTH('a)" shows "bit (sint w) n = (if n < l - 1 then bit w n else bit w (l - 1))" unfolding sint_uint l_def by (auto simp: bit_signed_take_bit_iff word_test_bit_def not_less min_def) lemma test_bit_2p: "bit (word_of_int (2 ^ n)::'a::len word) m \ m = n \ m < LENGTH('a)" by transfer (auto simp add: bit_exp_iff) lemma nth_w2p: "bit ((2::'a::len word) ^ n) m \ m = n \ m < LENGTH('a::len)" by transfer (auto simp add: bit_exp_iff) lemma bang_is_le: "bit x m \ 2 ^ m \ x" for x :: "'a::len word" apply (rule xtrans(3)) apply (rule_tac [2] y = "x" in le_word_or2) apply (rule word_eqI) apply (auto simp add: word_ao_nth nth_w2p word_size) done lemmas msb0 = len_gt_0 [THEN diff_Suc_less, THEN word_ops_nth_size [unfolded word_size]] lemmas msb1 = msb0 [where i = 0] lemma test_bit_1 [iff]: "bit (1 :: 'a::len word) n \ n = 0" by transfer (auto simp add: bit_1_iff) lemma nth_0: "\ bit (0 :: 'a::len word) n" by transfer simp lemma nth_minus1: "bit (-1 :: 'a::len word) n \ n < LENGTH('a)" by transfer simp lemma nth_ucast: "bit (ucast w::'a::len word) n = (bit w n \ n < LENGTH('a))" by transfer (simp add: bit_take_bit_iff ac_simps) lemma drop_bit_numeral_bit0_1 [simp]: \drop_bit (Suc 0) (numeral k) = (word_of_int (drop_bit (Suc 0) (take_bit LENGTH('a) (numeral k))) :: 'a::len word)\ by (metis Word_eq_word_of_int drop_bit_word.abs_eq of_int_numeral) lemma nth_mask: \bit (mask n :: 'a::len word) i \ i < n \ i < size (mask n :: 'a word)\ by (auto simp add: word_size Word.bit_mask_iff) lemma nth_slice: "bit (slice n w :: 'a::len word) m = (bit w (m + n) \ m < LENGTH('a))" apply (auto simp add: bit_simps less_diff_conv dest: bit_imp_le_length) using bit_imp_le_length apply fastforce done lemma test_bit_cat [OF refl]: "wc = word_cat a b \ bit wc n = (n < size wc \ (if n < size b then bit b n else bit a (n - size b)))" apply (simp add: word_size not_less; transfer) apply (auto simp add: bit_concat_bit_iff bit_take_bit_iff) done \ \keep quantifiers for use in simplification\ lemma test_bit_split': "word_split c = (a, b) \ (\n m. bit b n = (n < size b \ bit c n) \ bit a m = (m < size a \ bit c (m + size b)))" by (auto simp add: word_split_bin' bit_unsigned_iff word_size bit_drop_bit_eq ac_simps dest: bit_imp_le_length) lemma test_bit_split: "word_split c = (a, b) \ (\n::nat. bit b n \ n < size b \ bit c n) \ (\m::nat. bit a m \ m < size a \ bit c (m + size b))" by (simp add: test_bit_split') lemma test_bit_split_eq: "word_split c = (a, b) \ ((\n::nat. bit b n = (n < size b \ bit c n)) \ (\m::nat. bit a m = (m < size a \ bit c (m + size b))))" apply (rule_tac iffI) apply (rule_tac conjI) apply (erule test_bit_split [THEN conjunct1]) apply (erule test_bit_split [THEN conjunct2]) apply (case_tac "word_split c") apply (frule test_bit_split) apply (erule trans) apply (fastforce intro!: word_eqI simp add: word_size) done lemma test_bit_rcat: "sw = size (hd wl) \ rc = word_rcat wl \ bit rc n = (n < size rc \ n div sw < size wl \ bit ((rev wl) ! (n div sw)) (n mod sw))" for wl :: "'a::len word list" by (simp add: word_size word_rcat_def rev_map bit_horner_sum_uint_exp_iff bit_simps not_le) lemmas test_bit_cong = arg_cong [where f = "bit", THEN fun_cong] lemma max_test_bit: "bit (- 1::'a::len word) n \ n < LENGTH('a)" by (fact nth_minus1) lemma map_nth_0 [simp]: "map (bit (0::'a::len word)) xs = replicate (length xs) False" by (simp flip: map_replicate_const) lemma word_and_1: "n AND 1 = (if bit n 0 then 1 else 0)" for n :: "_ word" by (rule bit_word_eqI) (auto simp add: bit_and_iff bit_1_iff intro: gr0I) lemma test_bit_1': "bit (1 :: 'a :: len word) n \ 0 < LENGTH('a) \ n = 0" by simp lemma nth_w2p_same: "bit (2^n :: 'a :: len word) n = (n < LENGTH('a))" by (simp add: nth_w2p) lemma word_leI: "(\n. \n < size (u::'a::len word); bit u n \ \ bit (v::'a::len word) n) \ u <= v" apply (rule order_trans [of u \u AND v\ v]) apply (rule eq_refl) apply (rule bit_word_eqI) apply (auto simp add: bit_simps word_and_le1 word_size) done lemma bang_eq: fixes x :: "'a::len word" shows "(x = y) = (\n. bit x n = bit y n)" - by (auto simp add: bit_eq_iff) + by (auto intro!: bit_eqI) lemma neg_mask_test_bit: "bit (NOT(mask n) :: 'a :: len word) m = (n \ m \ m < LENGTH('a))" by (auto simp add: bit_simps) lemma upper_bits_unset_is_l2p: \(\n' \ n. n' < LENGTH('a) \ \ bit p n') \ (p < 2 ^ n)\ (is \?P \ ?Q\) if \n < LENGTH('a)\ for p :: "'a :: len word" proof assume ?Q then show ?P by (meson bang_is_le le_less_trans not_le word_power_increasing) next assume ?P have \take_bit n p = p\ proof (rule bit_word_eqI) fix q assume \q < LENGTH('a)\ show \bit (take_bit n p) q \ bit p q\ proof (cases \q < n\) case True then show ?thesis by (auto simp add: bit_simps) next case False then have \n \ q\ by simp with \?P\ \q < LENGTH('a)\ have \\ bit p q\ by simp then show ?thesis by (simp add: bit_simps) qed qed with that show ?Q using take_bit_word_eq_self_iff [of n p] by auto qed lemma less_2p_is_upper_bits_unset: "p < 2 ^ n \ n < LENGTH('a) \ (\n' \ n. n' < LENGTH('a) \ \ bit p n')" for p :: "'a :: len word" by (meson le_less_trans le_mask_iff_lt_2n upper_bits_unset_is_l2p word_zero_le) lemma test_bit_over: "n \ size (x::'a::len word) \ (bit x n) = False" by transfer auto lemma le_mask_high_bits: "w \ mask n \ (\i \ {n ..< size w}. \ bit w i)" for w :: \'a::len word\ apply (auto simp add: bit_simps word_size less_eq_mask_iff_take_bit_eq_self) apply (metis bit_take_bit_iff leD) apply (metis atLeastLessThan_iff leI take_bit_word_eq_self_iff upper_bits_unset_is_l2p) done lemma test_bit_conj_lt: "(bit x m \ m < LENGTH('a)) = bit x m" for x :: "'a :: len word" using test_bit_bin by blast lemma neg_test_bit: "bit (NOT x) n = (\ bit x n \ n < LENGTH('a))" for x :: "'a::len word" by (cases "n < LENGTH('a)") (auto simp add: test_bit_over word_ops_nth_size word_size) lemma nth_bounded: "\bit (x :: 'a :: len word) n; x < 2 ^ m; m \ len_of TYPE ('a)\ \ n < m" apply (rule ccontr) apply (auto simp add: not_less) apply (meson bit_imp_le_length bit_uint_iff less_2p_is_upper_bits_unset test_bit_bin) done lemma and_neq_0_is_nth: \x AND y \ 0 \ bit x n\ if \y = 2 ^ n\ for x y :: \'a::len word\ apply (simp add: bit_eq_iff bit_simps) using that apply (simp add: bit_simps not_le) apply transfer apply auto done lemma nth_is_and_neq_0: "bit (x::'a::len word) n = (x AND 2 ^ n \ 0)" by (subst and_neq_0_is_nth; rule refl) lemma max_word_not_less [simp]: "\ - 1 < x" for x :: \'a::len word\ by (fact word_order.extremum_strict) lemma bit_twiddle_min: "(y::'a::len word) XOR (((x::'a::len word) XOR y) AND (if x < y then -1 else 0)) = min x y" by (rule bit_eqI) (auto simp add: bit_simps) lemma bit_twiddle_max: "(x::'a::len word) XOR (((x::'a::len word) XOR y) AND (if x < y then -1 else 0)) = max x y" by (rule bit_eqI) (auto simp add: bit_simps max_def) lemma swap_with_xor: "\(x::'a::len word) = a XOR b; y = b XOR x; z = x XOR y\ \ z = b \ y = a" by (auto intro: bit_word_eqI simp add: bit_simps) lemma le_mask_imp_and_mask: "(x::'a::len word) \ mask n \ x AND mask n = x" by (metis and_mask_eq_iff_le_mask) lemma or_not_mask_nop: "((x::'a::len word) OR NOT (mask n)) AND mask n = x AND mask n" by (metis word_and_not word_ao_dist2 word_bw_comms(1) word_log_esimps(3)) lemma mask_subsume: "\n \ m\ \ ((x::'a::len word) OR y AND mask n) AND NOT (mask m) = x AND NOT (mask m)" by (rule bit_word_eqI) (auto simp add: bit_simps word_size) lemma and_mask_0_iff_le_mask: fixes w :: "'a::len word" shows "(w AND NOT(mask n) = 0) = (w \ mask n)" by (simp add: mask_eq_0_eq_x le_mask_imp_and_mask and_mask_eq_iff_le_mask) lemma mask_twice2: "n \ m \ ((x::'a::len word) AND mask m) AND mask n = x AND mask n" by (metis mask_twice min_def) lemma uint_2_id: "LENGTH('a) \ 2 \ uint (2::('a::len) word) = 2" by simp lemma div_of_0_id[simp]:"(0::('a::len) word) div n = 0" by (simp add: word_div_def) lemma degenerate_word:"LENGTH('a) = 1 \ (x::('a::len) word) = 0 \ x = 1" by (metis One_nat_def less_irrefl_nat sint_1_cases) lemma div_by_0_word:"(x::('a::len) word) div 0 = 0" by (metis div_0 div_by_0 unat_0 word_arith_nat_defs(6) word_div_1) lemma div_less_dividend_word:"\x \ 0; n \ 1\ \ (x::('a::len) word) div n < x" apply (cases \n = 0\) 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 word_less_div: fixes x :: "('a::len) word" and y :: "('a::len) word" shows "x div y = 0 \ y = 0 \ 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 \ (2::('a::len) word) \ 0" by (metis numerals(1) power_not_zero power_zero_numeral) lemma word_overflow:"(x::('a::len) word) + 1 > x \ 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 \ x + 1 = 0" by (metis Suc_eq_plus1 add.commute unatSuc) lemma even_word_imp_odd_next:"even (unat (x::('a::len) word)) \ x + 1 = 0 \ 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)) \ x + 1 = 0 \ 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 \ bit x 0" using even_plus_one_iff [of x] by simp lemma odd_iff_lsb:"odd (unat (x::('a::len) word)) = bit x 0" by transfer (simp add: even_nat_iff) lemma of_nat_neq_iff_word: "x mod 2 ^ LENGTH('a) \ y mod 2 ^ LENGTH('a) \ (((of_nat x)::('a::len) word) \ of_nat y) = (x \ y)" apply (rule iffI) apply (case_tac "x = y") apply (subst (asm) of_nat_eq_iff[symmetric]) apply auto apply (case_tac "((of_nat x)::('a::len) word) = of_nat y") apply auto apply (metis unat_of_nat) done lemma lsb_this_or_next: "\ (bit ((x::('a::len) word) + 1) 0) \ bit x 0" by simp lemma mask_or_not_mask: "x AND mask n OR x AND NOT (mask n) = x" for x :: \'a::len word\ apply (subst word_oa_dist, simp) apply (subst word_oa_dist2, simp) done lemma word_gr0_conv_Suc: "(m::'a::len word) > 0 \ \n. m = n + 1" by (metis add.commute add_minus_cancel) lemma revcast_down_us [OF refl]: "rc = revcast \ source_size rc = target_size rc + n \ rc w = ucast (signed_drop_bit n w)" for w :: "'a::len word" apply (simp add: source_size_def target_size_def) apply (rule bit_word_eqI) apply (simp add: bit_simps ac_simps) done lemma revcast_down_ss [OF refl]: "rc = revcast \ source_size rc = target_size rc + n \ rc w = scast (signed_drop_bit n w)" for w :: "'a::len word" apply (simp add: source_size_def target_size_def) apply (rule bit_word_eqI) apply (simp add: bit_simps ac_simps) done lemma revcast_down_uu [OF refl]: "rc = revcast \ source_size rc = target_size rc + n \ rc w = ucast (drop_bit n w)" for w :: "'a::len word" apply (simp add: source_size_def target_size_def) apply (rule bit_word_eqI) apply (simp add: bit_simps ac_simps) done lemma revcast_down_su [OF refl]: "rc = revcast \ source_size rc = target_size rc + n \ rc w = scast (drop_bit n w)" for w :: "'a::len word" apply (simp add: source_size_def target_size_def) apply (rule bit_word_eqI) apply (simp add: bit_simps ac_simps) done lemma cast_down_rev [OF refl]: "uc = ucast \ source_size uc = target_size uc + n \ uc w = revcast (push_bit n w)" for w :: "'a::len word" apply (simp add: source_size_def target_size_def) apply (rule bit_word_eqI) apply (simp add: bit_simps) done lemma revcast_up [OF refl]: "rc = revcast \ source_size rc + n = target_size rc \ rc w = push_bit n (ucast w :: 'a::len word)" apply (simp add: source_size_def target_size_def) apply (rule bit_word_eqI) apply (simp add: bit_simps) apply auto apply (metis add.commute add_diff_cancel_right) apply (metis diff_add_inverse2 diff_diff_add) done lemmas rc1 = revcast_up [THEN revcast_rev_ucast [symmetric, THEN trans, THEN word_rev_gal, symmetric]] lemmas rc2 = revcast_down_uu [THEN revcast_rev_ucast [symmetric, THEN trans, THEN word_rev_gal, symmetric]] lemma word_ops_nth: fixes x y :: \'a::len word\ shows word_or_nth: "bit (x OR y) n = (bit x n \ bit y n)" and word_and_nth: "bit (x AND y) n = (bit x n \ bit y n)" and word_xor_nth: "bit (x XOR y) n = (bit x n \ bit y n)" by (simp_all add: bit_simps) lemma word_power_nonzero: "\ (x :: 'a::len word) < 2 ^ (LENGTH('a) - n); n < LENGTH('a); x \ 0 \ \ x * 2 ^ n \ 0" by (metis gr_implies_not0 mult_eq_0_iff nat_mult_power_less_eq numeral_2_eq_2 p2_gt_0 unat_eq_zero unat_less_power unat_mult_lem unat_power_lower word_gt_a_gt_0 zero_less_Suc) lemma less_1_helper: "n \ m \ (n - 1 :: int) < m" by arith lemma div_power_helper: "\ x \ y; y < LENGTH('a) \ \ (2 ^ y - 1) div (2 ^ x :: 'a::len word) = 2 ^ (y - x) - 1" apply (simp flip: mask_eq_exp_minus_1 drop_bit_eq_div) apply (rule bit_word_eqI) apply (auto simp add: bit_simps not_le) done lemma max_word_mask: "(- 1 :: 'a::len word) = mask LENGTH('a)" by (fact minus_1_eq_mask) lemmas mask_len_max = max_word_mask[symmetric] lemma mask_out_first_mask_some: "\ x AND NOT (mask n) = y; n \ m \ \ x AND NOT (mask m) = y AND NOT (mask m)" for x y :: \'a::len word\ by (rule bit_word_eqI) (auto simp add: bit_simps word_size) lemma mask_lower_twice: "n \ m \ (x AND NOT (mask n)) AND NOT (mask m) = x AND NOT (mask m)" for x :: \'a::len word\ by (rule bit_word_eqI) (auto simp add: bit_simps word_size) lemma mask_lower_twice2: "(a AND NOT (mask n)) AND NOT (mask m) = a AND NOT (mask (max n m))" for a :: \'a::len word\ by (rule bit_word_eqI) (auto simp add: bit_simps) lemma ucast_and_neg_mask: "ucast (x AND NOT (mask n)) = ucast x AND NOT (mask n)" apply (rule bit_word_eqI) apply (auto simp add: bit_simps dest: bit_imp_le_length) done lemma ucast_and_mask: "ucast (x AND mask n) = ucast x AND mask n" apply (rule bit_word_eqI) apply (auto simp add: bit_simps dest: bit_imp_le_length) done lemma ucast_mask_drop: "LENGTH('a :: len) \ n \ (ucast (x AND mask n) :: 'a word) = ucast x" apply (rule bit_word_eqI) apply (auto simp add: bit_simps dest: bit_imp_le_length) done lemma mask_exceed: "n \ LENGTH('a) \ (x::'a::len word) AND NOT (mask n) = 0" by (rule bit_word_eqI) (simp add: bit_simps) lemma word_add_no_overflow:"(x::'a::len word) < - 1 \ 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 \ 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) \ LENGTH('b)" shows "unat (ucast x :: 'b::len word) = unat x" apply (rule bit_eqI) using assms apply (auto simp add: bit_simps dest: bit_imp_le_length) done lemma unat_ucast_less_no_overflow: "\n < 2 ^ LENGTH('a); unat f < n\ \ (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) \ (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 \ 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 \ 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] lemma minus_one_word: "(-1 :: 'a :: len word) = 2 ^ LENGTH('a) - 1" by simp lemma le_2p_upper_bits: "\ (p::'a::len word) \ 2^n - 1; n < LENGTH('a) \ \ \n'\n. n' < LENGTH('a) \ \ bit p n'" by (subst upper_bits_unset_is_l2p; simp) lemma le2p_bits_unset: "p \ 2 ^ n - 1 \ \n'\n. n' < LENGTH('a) \ \ bit (p::'a::len word) n'" using upper_bits_unset_is_l2p [where p=p] by (cases "n < LENGTH('a)") auto lemma complement_nth_w2p: shows "n' < LENGTH('a) \ bit (NOT (2 ^ n :: 'a::len word)) n' = (n' \ n)" by (fastforce simp: word_ops_nth_size word_size nth_w2p) lemma word_unat_and_lt: "unat x < n \ unat y < n \ unat (x AND y) < n" by (meson le_less_trans word_and_le1 word_and_le2 word_le_nat_alt) lemma word_unat_mask_lt: "m \ size w \ unat ((w::'a::len word) AND mask m) < 2 ^ m" by (rule word_unat_and_lt) (simp add: unat_mask word_size) lemma word_sless_sint_le:"x sint x \ sint y - 1" by (metis word_sless_alt zle_diff1_eq) lemma upper_trivial: fixes x :: "'a::len word" shows "x \ 2 ^ LENGTH('a) - 1 \ x < 2 ^ LENGTH('a) - 1" by (simp add: less_le) lemma constraint_expand: fixes x :: "'a::len word" shows "x \ {y. lower \ y \ y \ upper} = (lower \ x \ x \ upper)" by (rule mem_Collect_eq) lemma card_map_elide: "card ((of_nat :: nat \ 'a::len word) ` {0.. CARD('a::len word)" proof - let ?of_nat = "of_nat :: nat \ 'a word" have "inj_on ?of_nat {i. i < CARD('a word)}" by (rule inj_onI) (simp add: card_word of_nat_inj) moreover have "{0.. {i. i < CARD('a word)}" using that by auto ultimately have "inj_on ?of_nat {0.. CARD('a::len word) \ card ((of_nat::nat \ 'a::len word) ` {0.. LENGTH('a) \ x = ucast y \ ucast x = y" for x :: "'a::len word" and y :: "'b::len word" by transfer simp lemma le_ucast_ucast_le: "x \ ucast y \ ucast x \ 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) \ LENGTH('a) \ x < ucast y \ 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) \ LENGTH('b) \ (ucast x \ (ucast y::'b::len word)) = (x \ 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_or_distrib: fixes x :: "'a::len word" fixes y :: "'a::len word" shows "(ucast (x OR y) :: ('b::len) word) = ucast x OR ucast y" by (fact unsigned_or_eq) lemma word_exists_nth: "(w::'a::len word) \ 0 \ \i. bit w i" - by (simp add: bit_eq_iff) + by (auto simp add: bit_eq_iff) lemma max_word_not_0 [simp]: "- 1 \ (0 :: 'a::len word)" by simp lemma unat_max_word_pos[simp]: "0 < unat (- 1 :: 'a::len word)" using unat_gt_0 [of \- 1 :: 'a::len word\] by simp (* Miscellaneous conditional injectivity rules. *) lemma mult_pow2_inj: assumes ws: "m + n \ LENGTH('a)" assumes le: "x \ mask m" "y \ mask m" assumes eq: "x * 2 ^ n = y * (2 ^ n::'a::len word)" shows "x = y" proof (rule bit_word_eqI) fix q assume \q < LENGTH('a)\ from eq have \push_bit n x = push_bit n y\ by (simp add: push_bit_eq_mult) moreover from le have \take_bit m x = x\ \take_bit m y = y\ by (simp_all add: less_eq_mask_iff_take_bit_eq_self) ultimately have \push_bit n (take_bit m x) = push_bit n (take_bit m y)\ by simp_all with \q < LENGTH('a)\ ws show \bit x q \ bit y q\ apply (simp add: push_bit_take_bit) unfolding bit_eq_iff apply (simp add: bit_simps not_le) apply (metis (full_types) \take_bit m x = x\ \take_bit m y = y\ add.commute add_diff_cancel_right' add_less_cancel_right bit_take_bit_iff le_add2 less_le_trans) 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]) lemma word_of_int_bin_cat_eq_iff: "(word_of_int (concat_bit LENGTH('b) (uint b) (uint a))::'c::len word) = word_of_int (concat_bit LENGTH('b) (uint d) (uint c)) \ b = d \ a = c" if "LENGTH('a) + LENGTH('b) \ LENGTH('c)" for a::"'a::len word" and b::"'b::len word" proof - from that show ?thesis using that concat_bit_eq_iff [of \LENGTH('b)\ \uint b\ \uint a\ \uint d\ \uint c\] apply (simp add: word_of_int_eq_iff take_bit_int_eq_self flip: word_eq_iff_unsigned) apply (simp add: concat_bit_def take_bit_int_eq_self bintr_uint take_bit_push_bit) done qed lemma word_cat_inj: "(word_cat a b::'c::len word) = word_cat c d \ a = c \ b = d" if "LENGTH('a) + LENGTH('b) \ 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 (simp add: word_cat_eq' ac_simps) lemma p2_eq_1: "2 ^ n = (1::'a::len word) \ n = 0" proof - have "2 ^ n = (1::'a word) \ 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 end end diff --git a/thys/Word_Lib/More_Word_Operations.thy b/thys/Word_Lib/More_Word_Operations.thy --- a/thys/Word_Lib/More_Word_Operations.thy +++ b/thys/Word_Lib/More_Word_Operations.thy @@ -1,1032 +1,1023 @@ (* * Copyright Data61, CSIRO (ABN 41 687 119 230) * * SPDX-License-Identifier: BSD-2-Clause *) section \Misc word operations\ theory More_Word_Operations imports "HOL-Library.Word" Aligned Reversed_Bit_Lists More_Misc Signed_Words Word_Lemmas begin context includes bit_operations_syntax begin definition ptr_add :: "'a :: len word \ nat \ 'a word" where "ptr_add ptr n \ ptr + of_nat n" definition alignUp :: "'a::len word \ nat \ 'a word" where "alignUp x n \ x + 2 ^ n - 1 AND NOT (2 ^ n - 1)" lemma alignUp_unfold: \alignUp w n = (w + mask n) AND NOT (mask n)\ by (simp add: alignUp_def mask_eq_exp_minus_1 add_mask_fold) (* standard notation for blocks of 2^n-1 words, usually aligned; abbreviation so it simplifies directly *) abbreviation mask_range :: "'a::len word \ nat \ 'a word set" where "mask_range p n \ {p .. p + mask n}" definition w2byte :: "'a :: len word \ 8 word" where "w2byte \ ucast" (* Count leading zeros *) definition word_clz :: "'a::len word \ nat" where "word_clz w \ length (takeWhile Not (to_bl w))" (* Count trailing zeros *) definition word_ctz :: "'a::len word \ nat" where "word_ctz w \ length (takeWhile Not (rev (to_bl w)))" lemma word_ctz_le: "word_ctz (w :: ('a::len word)) \ LENGTH('a)" apply (clarsimp simp: word_ctz_def) using length_takeWhile_le apply (rule order_trans) apply simp done lemma word_ctz_less: "w \ 0 \ word_ctz (w :: ('a::len word)) < LENGTH('a)" apply (clarsimp simp: word_ctz_def eq_zero_set_bl) using length_takeWhile_less apply (rule less_le_trans) apply auto done lemma take_bit_word_ctz_eq [simp]: \take_bit LENGTH('a) (word_ctz w) = word_ctz w\ for w :: \'a::len word\ apply (simp add: take_bit_nat_eq_self_iff word_ctz_def to_bl_unfold) using length_takeWhile_le apply (rule le_less_trans) apply simp done lemma word_ctz_not_minus_1: \word_of_nat (word_ctz (w :: 'a :: len word)) \ (- 1 :: 'a::len word)\ if \1 < LENGTH('a)\ proof - note word_ctz_le also from that have \LENGTH('a) < mask LENGTH('a)\ by (simp add: less_mask) finally have \word_ctz w < mask LENGTH('a)\ . then have \word_of_nat (word_ctz w) < (word_of_nat (mask LENGTH('a)) :: 'a word)\ by (simp add: of_nat_word_less_iff) also have \\ = - 1\ by (rule bit_word_eqI) (simp add: bit_simps) finally show ?thesis by simp qed lemma unat_of_nat_ctz_mw: "unat (of_nat (word_ctz (w :: 'a :: len word)) :: 'a :: len word) = word_ctz w" by simp lemma unat_of_nat_ctz_smw: "unat (of_nat (word_ctz (w :: 'a :: len word)) :: 'a :: len signed word) = word_ctz w" by simp definition word_log2 :: "'a::len word \ nat" where "word_log2 (w::'a::len word) \ size w - 1 - word_clz w" (* Bit population count. Equivalent of __builtin_popcount. *) definition pop_count :: "('a::len) word \ nat" where "pop_count w \ length (filter id (to_bl w))" (* Sign extension from bit n *) definition sign_extend :: "nat \ 'a::len word \ 'a word" where "sign_extend n w \ if bit w n then w OR NOT (mask n) else w AND mask n" lemma sign_extend_eq_signed_take_bit: \sign_extend = signed_take_bit\ proof (rule ext)+ fix n and w :: \'a::len word\ show \sign_extend n w = signed_take_bit n w\ proof (rule bit_word_eqI) fix q assume \q < LENGTH('a)\ then show \bit (sign_extend n w) q \ bit (signed_take_bit n w) q\ by (auto simp add: 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 \ 'a::len word \ bool" where "sign_extended n w \ \i. n < i \ i < size w \ bit w i = bit w n" lemma ptr_add_0 [simp]: "ptr_add ref 0 = ref " unfolding ptr_add_def by simp 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 lemma word_log2_zero_eq [simp]: \word_log2 0 = 0\ by (simp add: word_log2_def word_clz_def word_size) lemma word_log2_unfold: \word_log2 w = (if w = 0 then 0 else Max {n. bit w n})\ for w :: \'a::len word\ proof (cases \w = 0\) case True then show ?thesis by simp next case False then obtain r where \bit w r\ by (auto simp add: bit_eq_iff) then have \Max {m. bit w m} = LENGTH('a) - Suc (length (takeWhile (Not \ bit w) (rev [0.. by (subst Max_eq_length_takeWhile [of _ \LENGTH('a)\]) (auto simp add: bit_imp_le_length) then have \word_log2 w = Max {x. bit w x}\ by (simp add: word_log2_def word_clz_def word_size to_bl_unfold rev_map takeWhile_map) with \w \ 0\ show ?thesis by simp qed lemma word_log2_eqI: \word_log2 w = n\ if \w \ 0\ \bit w n\ \\m. bit w m \ m \ n\ for w :: \'a::len word\ proof - from \w \ 0\ have \word_log2 w = Max {n. bit w n}\ by (simp add: word_log2_unfold) also have \Max {n. bit w n} = n\ using that by (auto intro: Max_eqI) finally show ?thesis . qed lemma bit_word_log2: \bit w (word_log2 w)\ if \w \ 0\ proof - from \w \ 0\ have \\r. bit w r\ - by (simp add: bit_eq_iff) + by (auto intro: bit_eqI) then obtain r where \bit w r\ .. from \w \ 0\ have \word_log2 w = Max {n. bit w n}\ by (simp add: word_log2_unfold) also have \Max {n. bit w n} \ {n. bit w n}\ using \bit w r\ by (subst Max_in) auto finally show ?thesis by simp qed lemma word_log2_maximum: \n \ word_log2 w\ if \bit w n\ proof - have \n \ Max {n. bit w n}\ using that by (auto intro: Max_ge) also from that have \w \ 0\ by force then have \Max {n. bit w n} = word_log2 w\ by (simp add: word_log2_unfold) finally show ?thesis . qed lemma word_log2_nth_same: "w \ 0 \ bit w (word_log2 w)" by (drule bit_word_log2) simp lemma word_log2_nth_not_set: "\ word_log2 w < i ; i < size w \ \ \ bit w i" using word_log2_maximum [of w i] by auto lemma word_log2_highest: assumes a: "bit w i" shows "i \ word_log2 w" using a by (simp add: word_log2_maximum) lemma word_log2_max: "word_log2 w < size w" apply (cases \w = 0\) apply (simp_all add: word_size) apply (drule bit_word_log2) apply (fact bit_imp_le_length) done lemma word_clz_0[simp]: "word_clz (0::'a::len word) = LENGTH('a)" unfolding word_clz_def by simp lemma word_clz_minus_one[simp]: "word_clz (-1::'a::len word) = 0" unfolding word_clz_def by simp lemma is_aligned_alignUp[simp]: "is_aligned (alignUp p n) n" by (simp add: alignUp_def is_aligned_mask mask_eq_decr_exp word_bw_assocs) lemma alignUp_le[simp]: "alignUp p n \ p + 2 ^ n - 1" unfolding alignUp_def by (rule word_and_le2) 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 add_cancel_right_right add_diff_eq and_mask_eq_iff_le_mask mask_eq_decr_exp mask_out_add_aligned order_refl word_plus_and_or_coroll2) lemma alignUp_not_aligned_eq: fixes a :: "'a :: len word" assumes al: "\ 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 \ 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 "\ = (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 mask_eq_decr_exp [symmetric]) 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 \ 0" shows "a \ 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 le_add_diff_inverse2 less_mult_imp_div_less order_less_imp_le power_add unsigned_less) have"2 ^ n * (unat a div 2 ^ n + 1) \ 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) \ 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) 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 "\ < (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 "\ = 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 \ x" and sz: "n < LENGTH('a)" and al: "is_aligned x n" shows "alignUp a n \ 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 \ 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 "\ \ 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 \ x" and az: "a \ 0" shows "alignUp (a::'a :: len word) n \ 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 \ 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 le_add_diff_inverse2 less_mult_imp_div_less order_less_imp_le power_add unsigned_less) have leq: "2 ^ n * (unat a div 2 ^ n + 1) \ 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 (simp flip: drop_bit_eq_div unat_drop_bit_eq) (metis leI le_unat_uoi unat_mono) have "alignUp a n = (a div 2 ^ n + 1) * 2 ^ n" by (rule alignUp_not_aligned_eq) fact+ then have "\ = 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, opaque_lifting) 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} \ {a..b}" and anz: "a \ 0" shows "a \ alignUp a n \ alignUp a n + 2 ^ n - 1 \ b" proof from al have xl: "x \ x + 2 ^ n - 1" by (simp add: is_aligned_no_overflow) from xl sub have ax: "a \ x" by auto show "a \ alignUp a n" proof (rule alignUp_ge) show "alignUp a n \ 0" using al sz ax anz by (rule alignUp_is_aligned_nz) qed fact+ show "alignUp a n + 2 ^ n - 1 \ b" proof (rule order_trans) from xl show tp: "x + 2 ^ n - 1 \ b" using sub by auto from ax have "alignUp a n \ x" by (rule alignUp_le_greater_al) fact+ then have "alignUp a n + (2 ^ n - 1) \ 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 \ x + 2 ^ n - 1" by (simp add: field_simps) qed qed lemma alignUp_def2: "alignUp a sz = a + 2 ^ sz - 1 AND NOT (mask sz)" by (simp add: alignUp_def flip: mask_eq_decr_exp) lemma alignUp_def3: "alignUp a sz = 2^ sz + (a - 1 AND NOT (mask sz))" by (simp add: alignUp_def2 is_aligned_triv field_simps mask_out_add_aligned) lemma alignUp_plus: "is_aligned w us \ alignUp (w + a) us = w + alignUp a us" by (clarsimp simp: alignUp_def2 mask_out_add_aligned field_simps) lemma alignUp_distance: "alignUp (q :: 'a :: len word) sz - q \ 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 \ (p - q AND NOT (mask sz)) = (p - ((alignUp q sz) AND NOT (mask sz)))" apply (clarsimp simp only:word_and_le2 diff_conv_add_uminus) apply (subst mask_out_add_aligned[symmetric]; simp) apply (simp add: eq_neg_iff_add_eq_0) apply (subst add.commute) apply (simp add: alignUp_distance is_aligned_neg_mask_eq mask_out_add_aligned and_mask_eq_iff_le_mask flip: mask_eq_x_eq_0) done lemma word_clz_max: "word_clz w \ 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 \ 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: "\j\set(to_bl w). \ j" by (metis a length_takeWhile_less less_irrefl_nat word_clz_def) hence "to_bl w = replicate (length (to_bl w)) False" using eq_zero_set_bl nz by fastforce 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 (* Sign extension from bit n. *) lemma bin_sign_extend_iff [bit_simps]: \bit (sign_extend e w) i \ bit w (min e i)\ if \i < LENGTH('a)\ for w :: \'a::len word\ using that by (simp add: sign_extend_def bit_simps min_def) lemma sign_extend_bitwise_if: "i < size w \ bit (sign_extend e w) i \ (if i < e then bit w i else bit w e)" by (simp add: word_size bit_simps) lemma sign_extend_bitwise_if' [word_eqI_simps]: \i < LENGTH('a) \ bit (sign_extend e w) i \ (if i < e then bit w i else bit w e)\ for w :: \'a::len word\ using sign_extend_bitwise_if [of i w e] by (simp add: word_size) lemma sign_extend_bitwise_disj: "i < size w \ bit (sign_extend e w) i \ i \ e \ bit w i \ e \ i \ bit w e" by (auto simp: sign_extend_bitwise_if) lemma sign_extend_bitwise_cases: "i < size w \ bit (sign_extend e w) i \ (i \ e \ bit w i) \ (e \ i \ bit w e)" by (auto simp: sign_extend_bitwise_if) 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 bit w n then w OR NOT (mask (Suc n)) else w AND mask (Suc n))" by (rule bit_word_eqI) (auto simp add: bit_simps sign_extend_eq_signed_take_bit min_def less_Suc_eq_le) 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 \ sign_extend n w = w" apply auto apply (auto simp add: bit_eq_iff) apply (simp_all add: bit_simps sign_extend_eq_signed_take_bit not_le min_def sign_extended_def word_size split: if_splits) using le_imp_less_or_eq apply auto[1] apply (metis bit_imp_le_length nat_less_le) apply (metis Suc_leI Suc_n_not_le_n le_trans nat_less_le) done lemma sign_extended_weaken: "sign_extended n w \ n \ m \ 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 (rule bit_word_eqI) (simp add: sign_extend_eq_signed_take_bit bit_simps) lemma sign_extended_high_bits: "\ sign_extended e p; j < size p; e \ i; i < j \ \ bit p i = bit p j" by (drule (1) sign_extended_weaken; simp add: sign_extended_def) lemma sign_extend_eq: "w AND mask (Suc n) = v AND mask (Suc n) \ sign_extend n w = sign_extend n v" by (simp flip: take_bit_eq_mask add: sign_extend_eq_signed_take_bit signed_take_bit_eq_iff_take_bit_eq) lemma sign_extended_add: assumes p: "is_aligned p n" assumes f: "f < 2 ^ n" assumes e: "n \ 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 "\ bit f e" using True e less_2p_is_upper_bits_unset[THEN iffD1, OF f] by (fastforce simp: word_size) hence i: "bit (p + f) e = bit p e" by (simp add: and_or bit_simps) have fm: "f AND mask e = f" by (fastforce intro: subst[where P="\f. f AND 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: "\sign_extended n ptr; m \ n\ \ sign_extended n (ptr AND NOT (mask m))" by (fastforce simp: sign_extended_def word_size neg_mask_test_bit bit_simps) definition "limited_and (x :: 'a :: len word) y \ (x AND y = x)" lemma limited_and_eq_0: "\ limited_and x z; y AND NOT z = y \ \ x AND y = 0" unfolding limited_and_def apply (subst arg_cong2[where f="(AND)"]) apply (erule sym)+ apply (simp(no_asm) add: word_bw_assocs word_bw_comms word_bw_lcs) done lemma limited_and_eq_id: "\ limited_and x z; y AND z = z \ \ x AND 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 \ limited_and (x << n) (z << n)" unfolding limited_and_def by (metis push_bit_and) lemma rshift_limited_and: "limited_and x z \ limited_and (x >> n) (z >> n)" unfolding limited_and_def by (metis drop_bit_and) 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] 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] not_one_eq definition from_bool :: "bool \ 'a::len word" where "from_bool b \ case b of True \ of_nat 1 | False \ of_nat 0" lemma from_bool_eq: \from_bool = of_bool\ by (simp add: fun_eq_iff from_bool_def) lemma from_bool_0: "(from_bool x = 0) = (\ x)" by (simp add: from_bool_def split: bool.split) lemma from_bool_eq_if': "((if P then 1 else 0) = from_bool Q) = (P = Q)" by (cases Q) (simp_all add: from_bool_def) definition to_bool :: "'a::len word \ bool" where "to_bool \ (\) 0" lemma to_bool_and_1: "to_bool (x AND 1) \ bit x 0" by (simp add: 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 \ 0) = b" by (simp add: from_bool_def split: bool.splits) lemma from_bool_mask_simp [simp]: "(from_bool r :: 'a::len word) AND 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]: "\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 (cases Q) (simp_all add: from_bool_def) lemma to_bool_eq_0: "(\ to_bool x) = (x = 0)" by (simp add: to_bool_def) lemma to_bool_neq_0: "(to_bool x) = (x \ 0)" by (simp add: to_bool_def) lemma from_bool_all_helper: "(\bool. from_bool bool = val \ P bool) = ((\bool. from_bool bool = val) \ P (val \ 0))" by (auto simp: from_bool_0) lemma fold_eq_0_to_bool: "(v = 0) = (\ to_bool v)" by (simp add: to_bool_def) lemma from_bool_to_bool_iff: "w = from_bool b \ to_bool w = b \ (w = 0 \ w = 1)" by (cases b) (auto simp: from_bool_def to_bool_def) lemma from_bool_eqI: "from_bool x = from_bool y \ x = y" unfolding from_bool_def by (auto split: bool.splits) lemma neg_mask_in_mask_range: "is_aligned ptr bits \ (ptr' AND NOT(mask bits) = ptr) = (ptr' \ 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 bit.disj_ac(2) bit.disj_conj_distrib2 le_word_or2 word_and_max word_or_not) 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: "\ is_aligned (x :: 'a :: len word) m; y < 2 ^ m; is_aligned p n; n \ m; n < LENGTH('a) \ \ (x + y \ {p .. p + mask n}) = (x \ mask_range p n)" apply (subst disjunctive_add) apply (simp add: bit_simps) apply (erule is_alignedE') apply (auto simp add: bit_simps not_le)[1] apply (metis less_2p_is_upper_bits_unset) apply (simp only: is_aligned_add_or word_ao_dist flip: neg_mask_in_mask_range) apply (subgoal_tac \y AND NOT (mask n) = 0\) apply simp apply (metis (full_types) is_aligned_mask is_aligned_neg_mask less_mask_eq word_bw_comms(1) word_bw_lcs(1)) done lemma mask_range_to_bl': "\ is_aligned (ptr :: 'a :: len word) bits; bits < LENGTH('a) \ \ 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 "\y. x = ptr + y \ 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 "\y. y < 2 ^ bits \ 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 \ 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: "\ is_aligned (p :: 'a :: len word) n; is_aligned (p' :: 'a :: len word) n' \ \ mask_range p n \ mask_range p' n' = {} \ mask_range p n \ mask_range p' n' \ mask_range p n \ mask_range p' n'" apply (simp add: mask_range_to_bl) apply (rule Meson.disj_comm, rule disjCI) apply auto apply (subgoal_tac "(\n''. LENGTH('a) - n = (LENGTH('a) - n') + n'') \ (\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' \ sz" and xsz: "x < 2 ^ sz" shows "mask_range (ptr+x) sz' \ mask_range ptr sz" using al proof (rule is_aligned_get_word_bits) assume p0: "ptr = 0" and szv': "LENGTH ('a) \ sz" then have "(2 ::'a word) ^ sz = 0" by simp show ?thesis using p0 by (simp add: \2 ^ sz = 0\ 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 auto using al assms(4) is_aligned_no_wrap' apply blast 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_ranges_disjoint: "\ is_aligned (p :: 'a :: len word) n; is_aligned (p' :: 'a :: len word) n'; p AND NOT(mask n') \ p'; p' AND NOT(mask n) \ p \ \ mask_range p n \ mask_range p' n' = {}" using aligned_mask_range_cases by (auto simp: neg_mask_in_mask_range) lemma aligned_mask_ranges_disjoint2: "\ is_aligned p n; is_aligned ptr bits; n \ m; n < size p; m \ bits; (\y < 2 ^ (n - m). p + (y << m) \ mask_range ptr bits) \ \ mask_range p n \ mask_range ptr bits = {}" apply safe apply (simp only: flip: neg_mask_in_mask_range) - apply simp apply (drule_tac x="x AND mask n >> m" in spec) - apply (auto simp add: and_mask_less_size wsst_TYs multiple_mask_trivia neg_mask_twice - word_bw_assocs max_absorb2) - apply (erule notE) - - apply (simp add: shiftr_mask2) - apply (rule and_mask_less') - apply simp - apply (subst (asm) disjunctive_add) - apply (simp add: bit_simps) - apply auto - apply (erule notE) - apply (rule bit_word_eqI) - apply (auto simp add: bit_simps) + apply (erule notE[OF mp]) + apply (rule shiftr_less_t2n) + apply (simp add: word_size and_mask_less_size) + apply (subst disjunctive_add) + apply (auto simp add: bit_simps word_size intro!: bit_eqI) done lemma word_clz_sint_upper[simp]: "LENGTH('a) \ 3 \ sint (of_nat (word_clz (w :: 'a :: len word)) :: 'a sword) \ int (LENGTH('a))" using word_clz_max [of w] apply (simp add: word_size) apply (subst signed_take_bit_int_eq_self) apply simp_all apply (metis negative_zle of_nat_numeral semiring_1_class.of_nat_power) apply (drule small_powers_of_2) apply (erule le_less_trans) apply simp done lemma word_clz_sint_lower[simp]: "LENGTH('a) \ 3 \ - sint (of_nat (word_clz (w :: 'a :: len word)) :: 'a signed word) \ int (LENGTH('a))" apply (subst sint_eq_uint) using word_clz_max [of w] apply (simp_all add: word_size) apply (rule not_msb_from_less) apply (simp add: word_less_nat_alt) apply (subst take_bit_nat_eq_self) apply (simp add: le_less_trans) apply (drule small_powers_of_2) apply (erule le_less_trans) apply simp done lemma mask_range_subsetD: "\ p' \ mask_range p n; x' \ mask_range p' n'; n' \ n; is_aligned p n; is_aligned p' n' \ \ x' \ mask_range p n" using aligned_mask_step by fastforce lemma nasty_split_lt: "\ (x :: 'a:: len word) < 2 ^ (m - n); n \ m; m < LENGTH('a::len) \ \ x * 2 ^ n + (2 ^ n - 1) \ 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: "\m \ n; n \ nm; nm < LENGTH('a::len); x < 2 ^ (nm - n)\ \ (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 add_mult_in_mask_range: "\ is_aligned (base :: 'a :: len word) n; n < LENGTH('a); bits \ n; x < 2 ^ (n - bits) \ \ base + x * 2^bits \ 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 from_to_bool_last_bit: "from_bool (to_bool (x AND 1)) = x AND 1" by (metis from_bool_to_bool_iff word_and_1) lemma sint_ctz: "LENGTH('a) > 2 \ 0 \ sint (of_nat (word_ctz (x :: 'a :: len word)) :: 'a signed word) \ sint (of_nat (word_ctz x) :: 'a signed word) \ 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) using small_powers_of_2 [of \LENGTH('a)\] by simp lemma unat_of_nat_word_log2: "LENGTH('a) < 2 ^ LENGTH('b) \ 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_mask_diff: "\ is_aligned (dest :: 'a :: len word) bits; is_aligned (ptr :: 'a :: len word) sz; bits \ sz; sz < LENGTH('a); dest < ptr \ \ 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) apply (simp add: is_aligned_weaken algebra_split_simps) apply (auto simp add: not_le) using is_aligned_no_overflow_mask leD apply blast apply (meson aligned_add_mask_less_eq is_aligned_weaken le_less_trans) done end end \ No newline at end of file