mirror of
https://github.com/Mercury-Language/mercury.git
synced 2026-04-24 22:04:13 +00:00
42ec93ecde
Estimated hours taken: 0.5 library/random.m: Remove random__bit_reverse. Use backtrackable unique modes rather than unique modes.
92 lines
2.4 KiB
Mathematica
92 lines
2.4 KiB
Mathematica
%---------------------------------------------------------------------------%
|
|
% Copyright (C) 1995 University of Melbourne.
|
|
% This file may only be copied under the terms of the GNU Library General
|
|
% Public License - see the file COPYING.LIB in the Mercury distribution.
|
|
%---------------------------------------------------------------------------%
|
|
%
|
|
% file: rand.m
|
|
% main author: conway
|
|
% stability: low
|
|
%
|
|
% Define a set of random number generator predicates. This implementation
|
|
% uses a threaded random-number supply. It could be made non-unique, but
|
|
% since each thread returns the same list of random numbers, in the interests
|
|
% of safety, it is declared with (backtrackable) unique modes.
|
|
%
|
|
%---------------------------------------------------------------------------%
|
|
|
|
:- module random.
|
|
|
|
:- interface.
|
|
|
|
:- import_module int, list.
|
|
|
|
:- type random__supply.
|
|
|
|
:- pred random__init(int, random__supply).
|
|
:- mode random__init(in, uo) is det.
|
|
|
|
:- pred random__random(int, random__supply, random__supply).
|
|
:- mode random__random(out, mdi, muo) is det.
|
|
|
|
:- pred random__randmax(int, random__supply, random__supply).
|
|
:- mode random__randmax(out, mdi, muo) is det.
|
|
|
|
:- pred random__test(int, int, list(int), int).
|
|
:- mode random__test(in, in, out, out) is det.
|
|
|
|
%---------------------------------------------------------------------------%
|
|
|
|
:- implementation.
|
|
:- import_module require.
|
|
|
|
:- type random__supply == int. % I(j)
|
|
|
|
:- pred random__params(int, int, int). % a, c, m
|
|
:- mode random__params(out, out, out) is det.
|
|
|
|
random__params(2416, 374441, 1771875).
|
|
|
|
random__init(I0, RS) :-
|
|
copy(I0, RS).
|
|
|
|
random__random(I, RS0, RS) :-
|
|
RS0 = I0,
|
|
random__params(A, C, M),
|
|
I1 is I0 * A,
|
|
I2 is I1 + C,
|
|
I is I2 mod M,
|
|
copy(I, RS).
|
|
|
|
random__randmax(M1, Rs0, Rs) :-
|
|
Rs0 = I,
|
|
random__params(_A, _C, M),
|
|
M1 is M - 1,
|
|
Rs = I.
|
|
|
|
%---------------------------------------------------------------------------%
|
|
%---------------------------------------------------------------------------%
|
|
|
|
random__test(Seed, N, Nums, Max) :-
|
|
random__init(Seed, RS),
|
|
random__randmax(Max, RS, RS1),
|
|
random__test_2(N, Nums, RS1, _RS2).
|
|
|
|
:- pred random__test_2(int, list(int), random__supply, random__supply).
|
|
:- mode random__test_2(in, out, mdi, muo) is det.
|
|
|
|
random__test_2(N, Is, RS0, RS) :-
|
|
(
|
|
N > 0
|
|
->
|
|
N1 is N - 1,
|
|
random__random(I, RS0, RS1),
|
|
random__test_2(N1, Is0, RS1, RS),
|
|
Is = [I|Is0]
|
|
;
|
|
Is = [],
|
|
RS = RS0
|
|
).
|
|
|
|
%---------------------------------------------------------------------------%
|