--- a/src/HOL/Library/Code_Target_Bit_Shifts.thy Fri Apr 04 23:12:20 2025 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,182 +0,0 @@
-(* Title: HOL/Library/Code_Target_Bit_Shifts.thy
- Author: Florian Haftmann, TU Muenchen
-*)
-
-section \<open>Implementation of bit-shifts on target-language integers by built-in operations\<close>
-
-theory Code_Target_Bit_Shifts
-imports Main
-begin
-
-context
-begin
-
-qualified definition push_bit :: \<open>integer \<Rightarrow> integer \<Rightarrow> integer\<close>
- where \<open>push_bit i k = Bit_Operations.push_bit (nat_of_integer \<bar>i\<bar>) k\<close>
-
-qualified lemma push_bit_code [code]:
- \<open>push_bit i k = k * 2 ^ nat_of_integer \<bar>i\<bar>\<close>
- by (simp add: push_bit_def push_bit_eq_mult)
-
-lemma push_bit_integer_code [code]:
- \<open>Bit_Operations.push_bit n k = push_bit (of_nat n) k\<close>
- by (simp add: push_bit_def)
-
-qualified definition drop_bit :: \<open>integer \<Rightarrow> integer \<Rightarrow> integer\<close>
- where \<open>drop_bit i k = Bit_Operations.drop_bit (nat_of_integer \<bar>i\<bar>) k\<close>
-
-qualified lemma drop_bit_code [code]:
- \<open>drop_bit i k = k div 2 ^ nat_of_integer \<bar>i\<bar>\<close>
- by (simp add: drop_bit_def drop_bit_eq_div)
-
-lemma drop_bit_integer_code [code]:
- \<open>Bit_Operations.drop_bit n k = drop_bit (of_nat n) k\<close>
- by (simp add: drop_bit_def)
-
-end
-
-code_printing code_module Bit_Shifts \<rightharpoonup>
- (SML) \<open>
-structure Bit_Shifts : sig
- type int = IntInf.int
- val push : int -> int -> int
- val drop : int -> int -> int
- val word_max_index : Word.word (*only for validation*)
-end = struct
-
-open IntInf;
-
-fun fold _ [] y = y
- | fold f (x :: xs) y = fold f xs (f x y);
-
-fun replicate n x = (if n <= 0 then [] else x :: replicate (n - 1) x);
-
-val max_index = pow (fromInt 2, Int.- (Word.wordSize, 3)) - fromInt 1; (*experimentally determined*)
-
-val word_of_int = Word.fromLargeInt o toLarge;
-
-val word_max_index = word_of_int max_index;
-
-fun words_of_int k = case divMod (k, max_index)
- of (b, s) => word_of_int s :: (replicate b word_max_index);
-
-fun push' i k = << (k, i);
-
-fun drop' i k = ~>> (k, i);
-
-(* The implementations are formally total, though indices >~ max_index will produce heavy computation load *)
-
-fun push i = fold push' (words_of_int (abs i));
-
-fun drop i = fold drop' (words_of_int (abs i));
-
-end;\<close> for constant Code_Target_Bit_Shifts.push_bit Code_Target_Bit_Shifts.drop_bit
- and (OCaml) \<open>
-module Bit_Shifts : sig
- val push : Z.t -> Z.t -> Z.t
- val drop : Z.t -> Z.t -> Z.t
-end = struct
-
-let rec fold f xs y = match xs with
- [] -> y
- | (x :: xs) -> fold f xs (f x y);;
-
-let rec replicate n x = (if Z.leq n Z.zero then [] else x :: replicate (Z.pred n) x);;
-
-let max_index = Z.of_int max_int;;
-
-let splitIndex i = let (b, s) = Z.div_rem i max_index
- in Z.to_int s :: (replicate b max_int);;
-
-let push' i k = Z.shift_left k i;;
-
-let drop' i k = Z.shift_right k i;;
-
-(* The implementations are formally total, though indices >~ max_index will produce heavy computation load *)
-
-let push i = fold push' (splitIndex (Z.abs i));;
-
-let drop i = fold drop' (splitIndex (Z.abs i));;
-
-end;;
-\<close> for constant Code_Target_Bit_Shifts.push_bit Code_Target_Bit_Shifts.drop_bit
- and (Haskell) \<open>
-module Bit_Shifts (push, drop, push', drop') where
-
-import Prelude (Int, Integer, toInteger, fromInteger, maxBound, divMod, (-), (<=), abs, flip)
-import GHC.Bits (Bits)
-import Data.Bits (shiftL, shiftR)
-
-fold :: (a -> b -> b) -> [a] -> b -> b
-fold _ [] y = y
-fold f (x : xs) y = fold f xs (f x y)
-
-replicate :: Integer -> a -> [a]
-replicate k x = if k <= 0 then [] else x : replicate (k - 1) x
-
-maxIndex :: Integer
-maxIndex = toInteger (maxBound :: Int)
-
-splitIndex :: Integer -> [Int]
-splitIndex i = fromInteger s : replicate (fromInteger b) maxBound
- where (b, s) = i `divMod` maxIndex
-
-{- The implementations are formally total, though indices >~ maxIndex will produce heavy computation load -}
-
-push :: Integer -> Integer -> Integer
-push i = fold (flip shiftL) (splitIndex (abs i))
-
-drop :: Integer -> Integer -> Integer
-drop i = fold (flip shiftR) (splitIndex (abs i))
-
-push' :: Int -> Int -> Int
-push' i = flip shiftL (abs i)
-
-drop' :: Int -> Int -> Int
-drop' i = flip shiftR (abs i)
-\<close> for constant Code_Target_Bit_Shifts.push_bit Code_Target_Bit_Shifts.drop_bit
- and (Scala) \<open>
-object Bit_Shifts {
-
-private val maxIndex : BigInt = BigInt(Int.MaxValue);
-
-private def replicate[A](i : BigInt, x : A) : List[A] =
- i <= 0 match {
- case true => Nil
- case false => x :: replicate[A](i - 1, x)
- }
-
-private def splitIndex(i : BigInt) : List[Int] = {
- val (b, s) = i /% maxIndex
- return s.intValue :: replicate(b, Int.MaxValue)
-}
-
-/* The implementations are formally total, though indices >~ maxIndex will produce heavy computation load */
-
-def push(i: BigInt, k: BigInt) : BigInt =
- splitIndex(i).foldLeft(k) { (l, j) => l << j }
-
-def drop(i: BigInt, k: BigInt) : BigInt =
- splitIndex(i).foldLeft(k) { (l, j) => l >> j }
-
-}
-\<close> for constant Code_Target_Bit_Shifts.push_bit Code_Target_Bit_Shifts.drop_bit
-| constant Code_Target_Bit_Shifts.push_bit \<rightharpoonup>
- (SML) "Bit'_Shifts.push"
- and (OCaml) "Bit'_Shifts.push"
- and (Haskell) "Bit'_Shifts.push"
- and (Haskell_Quickcheck) "Bit'_Shifts.push'"
- and (Scala) "Bit'_Shifts.push"
-| constant Code_Target_Bit_Shifts.drop_bit \<rightharpoonup>
- (SML) "Bit'_Shifts.drop"
- and (OCaml) "Bit'_Shifts.drop"
- and (Haskell) "Bit'_Shifts.drop"
- and (Haskell_Quickcheck) "Bit'_Shifts.drop'"
- and (Scala) "Bit'_Shifts.drop"
-
-code_reserved
- (SML) Bit_Shifts
- and (Haskell) Bit_Shifts
- and (Scala) Bit_Shifts
-
-end