102 lines
3.9 KiB
OCaml
102 lines
3.9 KiB
OCaml
(**************************************************************************)
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(* *)
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(* OCaml *)
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(* *)
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(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
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(* *)
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(* Copyright 1996 Institut National de Recherche en Informatique et *)
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(* en Automatique. *)
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(* *)
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(* All rights reserved. This file is distributed under the terms of *)
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(* the GNU Lesser General Public License version 2.1, with the *)
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(* special exception on linking described in the file LICENSE. *)
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(* *)
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(**************************************************************************)
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(* Module [Int32]: 32-bit integers *)
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external neg : int32 -> int32 = "%int32_neg"
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external add : int32 -> int32 -> int32 = "%int32_add"
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external sub : int32 -> int32 -> int32 = "%int32_sub"
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external mul : int32 -> int32 -> int32 = "%int32_mul"
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external div : int32 -> int32 -> int32 = "%int32_div"
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external rem : int32 -> int32 -> int32 = "%int32_mod"
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external logand : int32 -> int32 -> int32 = "%int32_and"
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external logor : int32 -> int32 -> int32 = "%int32_or"
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external logxor : int32 -> int32 -> int32 = "%int32_xor"
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external shift_left : int32 -> int -> int32 = "%int32_lsl"
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external shift_right : int32 -> int -> int32 = "%int32_asr"
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external shift_right_logical : int32 -> int -> int32 = "%int32_lsr"
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external of_int : int -> int32 = "%int32_of_int"
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external to_int : int32 -> int = "%int32_to_int"
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external of_float : float -> int32
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= "caml_int32_of_float" "caml_int32_of_float_unboxed"
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[@@unboxed] [@@noalloc]
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external to_float : int32 -> float
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= "caml_int32_to_float" "caml_int32_to_float_unboxed"
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[@@unboxed] [@@noalloc]
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external bits_of_float : float -> int32
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= "caml_int32_bits_of_float" "caml_int32_bits_of_float_unboxed"
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[@@unboxed] [@@noalloc]
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external float_of_bits : int32 -> float
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= "caml_int32_float_of_bits" "caml_int32_float_of_bits_unboxed"
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[@@unboxed] [@@noalloc]
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let zero = 0l
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let one = 1l
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let minus_one = -1l
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let succ n = add n 1l
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let pred n = sub n 1l
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let abs n = if n >= 0l then n else neg n
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let min_int = 0x80000000l
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let max_int = 0x7FFFFFFFl
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let lognot n = logxor n (-1l)
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let unsigned_to_int =
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match Sys.word_size with
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| 32 ->
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let max_int = of_int Stdlib.max_int in
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fun n ->
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if compare zero n <= 0 && compare n max_int <= 0 then
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Some (to_int n)
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else
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None
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| 64 ->
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(* So that it compiles in 32-bit *)
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let move = int_of_string "0x1_0000_0000" in
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fun n -> let i = to_int n in Some (if i < 0 then i + move else i)
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| _ ->
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assert false
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external format : string -> int32 -> string = "caml_int32_format"
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let to_string n = format "%d" n
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external of_string : string -> int32 = "caml_int32_of_string"
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let of_string_opt s =
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(* TODO: expose a non-raising primitive directly. *)
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try Some (of_string s)
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with Failure _ -> None
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type t = int32
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let compare (x: t) (y: t) = Stdlib.compare x y
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let equal (x: t) (y: t) = compare x y = 0
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let unsigned_compare n m =
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compare (sub n min_int) (sub m min_int)
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(* Unsigned division from signed division of the same
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bitness. See Warren Jr., Henry S. (2013). Hacker's Delight (2 ed.), Sec 9-3.
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*)
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let unsigned_div n d =
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if d < zero then
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if unsigned_compare n d < 0 then zero else one
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else
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let q = shift_left (div (shift_right_logical n 1) d) 1 in
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let r = sub n (mul q d) in
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if unsigned_compare r d >= 0 then succ q else q
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let unsigned_rem n d =
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sub n (mul (unsigned_div n d) d)
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