Source file `int8_u.ml`

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(**************************************************************************)
(*                                                                        *)
(*                                 OCaml                                  *)
(*                                                                        *)
(*                 Jacob Van Buren, Jane Street, New York                 *)
(*                                                                        *)
(*   Copyright 2024 Jane Street Group LLC                                 *)
(*                                                                        *)
(*   All rights reserved.  This file is distributed under the terms of    *)
(*   the GNU Lesser General Public License version 2.1, with the          *)
(*   special exception on linking described in the file LICENSE.          *)
(*                                                                        *)
(**************************************************************************)

[@@@ocaml.flambda_o3]

open! Stdlib

type t = int8#

let size = 8

external of_int8 : int8 -> int8# @@ portable = "%int8#_of_int8"

external to_int8 : int8# -> int8 @@ portable = "%int8_of_int8#"

external of_int : int -> int8# @@ portable = "%int8#_of_int"

external to_int : int8# -> int @@ portable = "%int_of_int8#"

external ( < ) : int8# -> int8# -> bool @@ portable = "%int8#_lessthan"

let zero () = of_int 0

let one () = of_int 1

let minus_one () = of_int (-1)

external neg : int8# -> int8# @@ portable = "%int8#_neg"

external add : int8# -> int8# -> int8# @@ portable = "%int8#_add"

external sub : int8# -> int8# -> int8# @@ portable = "%int8#_sub"

external mul : int8# -> int8# -> int8# @@ portable = "%int8#_mul"

external div : int8# -> int8# -> int8# @@ portable = "%int8#_div"

external rem : int8# -> int8# -> int8# @@ portable = "%int8#_mod"

external succ : int8# -> int8# @@ portable = "%int8#_succ"

external pred : int8# -> int8# @@ portable = "%int8#_pred"

external logand : int8# -> int8# -> int8# @@ portable = "%int8#_and"

external logor : int8# -> int8# -> int8# @@ portable = "%int8#_or"

external logxor : int8# -> int8# -> int8# @@ portable = "%int8#_xor"

let[@inline] lognot x = logxor x (minus_one ())

external shift_left : int8# -> int -> int8# @@ portable = "%int8#_lsl"

external shift_right : int8# -> int -> int8# @@ portable = "%int8#_asr"

external shift_right_logical : int8# -> int -> int8# @@ portable = "%int8#_lsr"

let[@inline] abs x = if x < zero () then neg x else x

external equal : int8# -> int8# -> bool @@ portable = "%int8#_equal"

external compare : int8# -> int8# -> int @@ portable = "%int8#_compare"

let[@inline] min x y = if x < y then x else y

let[@inline] max x y = if x < y then y else x

external of_float : float -> int8# @@ portable = "%int8#_of_float"

external to_float : int8# -> float @@ portable = "%float_of_int8#"

let[@inline] to_string t = Int.to_string (to_int t)

let[@inline] of_string s = of_int8 (Int8.of_string s)

let max_int () = shift_right_logical (minus_one ()) 1

let min_int () = succ (max_int ())

let[@inline] unsigned_to_int t = to_int t land ((1 lsl size) - 1)

external unsigned_compare : int8# -> int8# -> int @@ portable
  = "%int8#_unsigned_compare"

external unsigned_lt : int8# -> int8# -> bool @@ portable
  = "%int8#_unsigned_lessthan"

(* Unsigned division from signed division of the same bitness. See Warren Jr.,
   Henry S. (2013). Hacker's Delight (2 ed.), Sec 9-3. *)
let[@inline] unsigned_div n d =
  if d < zero ()
  then if unsigned_lt n d then zero () else one ()
  else
    let q = shift_left (div (shift_right_logical n 1) d) 1 in
    let r = sub n (mul q d) in
    if unsigned_lt r d then q else succ q

let[@inline] unsigned_rem n d = sub n (mul (unsigned_div n d) d)

let seeded_hash seed x = Stdlib.Hashtbl.seeded_hash seed (to_int x)

let hash x = Stdlib.Hashtbl.hash (to_int x)