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(****************************************************************************)
(* the diy toolsuite *)
(* *)
(* Jade Alglave, University College London, UK. *)
(* Luc Maranget, INRIA Paris-Rocquencourt, France. *)
(* *)
(* Copyright 2015-present Institut National de Recherche en Informatique et *)
(* en Automatique and the authors. All rights reserved. *)
(* *)
(* This software is governed by the CeCILL-B license under French law and *)
(* abiding by the rules of distribution of free software. You can use, *)
(* modify and/ or redistribute the software under the terms of the CeCILL-B *)
(* license as circulated by CEA, CNRS and INRIA at the following URL *)
(* "http://www.cecill.info". We also give a copy in LICENSE.txt. *)
(****************************************************************************)
(** Signed 128-bit integer types in pure OCaml. *)
module Int128 = struct
include BaseUint128
let max_int = Int64.max_int,BaseUint64.max_int
let chsgn a = add (lognot a) one
let minus_one = chsgn one
let is_neg (ah,_) = BaseUint64.has_top_bit_set ah
let abs x = if is_neg x then chsgn x else x
let compare a b =
match is_neg a,is_neg b with
| true,true -> compare b a
| false,false -> compare a b
| true,false -> -1
| false,true -> +1
let unsigned_compare a b =
match Int64.unsigned_compare (fst a) (fst b) with
| 0 -> Int64.unsigned_compare (snd a) (snd b)
| n -> n
let div_and_rem a b =
if is_neg b then raise (Failure "division by negative number")
else if is_neg a then
(* Signed euclidian division, with remainder in [0..b) *)
let a = chsgn a in
let q,r = div_and_rem a b in
if equal r zero then chsgn q,r
else chsgn (succ q),sub b r
else div_and_rem a b
let div a b =
let q,_ = div_and_rem a b in q
let rem a b =
let _,r = div_and_rem a b in r
let to_string a =
if is_neg a then "-" ^ to_string (chsgn a)
else to_string a
let of_string raw =
let len = String.length raw in
if len > 0 && raw.[0] = '-' then
chsgn (of_string (String.sub raw 1 (len-1)))
else of_string raw
end
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