ligo/src/lib_crypto/zplus.ml
2018-08-31 15:46:57 +02:00

74 lines
2.8 KiB
OCaml

(*****************************************************************************)
(* *)
(* Open Source License *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
(* *)
(* Permission is hereby granted, free of charge, to any person obtaining a *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense, *)
(* and/or sell copies of the Software, and to permit persons to whom the *)
(* Software is furnished to do so, subject to the following conditions: *)
(* *)
(* The above copyright notice and this permission notice shall be included *)
(* in all copies or substantial portions of the Software. *)
(* *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *)
(* DEALINGS IN THE SOFTWARE. *)
(* *)
(*****************************************************************************)
(* let re_trailing_null =
Re_pcre.regexp "^(.*?)\000*$"
let remove_trailing_null s =
Re.get (Re.exec re_trailing_null s) 1 *)
let remove_trailing_null s =
let n = String.length s in
let i = ref (n-1) in
while (!i >= 0) && (String.get s !i = '\000') do
i := !i - 1
done; String.sub s 0 (!i+1)
let serialize z =
let n =
if Z.(lt z zero) then
Z.(neg (add (add z z) one))
else
Z.(add z z)
in
n |> Z.to_bits |> remove_trailing_null
let deserialize z =
let n = Z.of_bits z in
let z = Z.shift_right_trunc n 1 in
if Z.(n land one = zero) then z else Z.neg z
let leq a b = (Z.compare a b) <= 0
let geq a b = (Z.compare a b) >= 0
let lt a b = (Z.compare a b) < 0
let gt a b = (Z.compare a b) > 0
let (<) = lt
let (>) = gt
let (<=) = leq
let (>=) = geq
let zero = Z.zero
let one = Z.one
let invert a n =
try
Some (Z.invert a n)
with
Division_by_zero -> None