/* GNU Chess 5.0 - random.c - random number code
Copyright (c) 1999-2002 Free Software Foundation, Inc.
GNU Chess is based on the two research programs
Cobalt by Chua Kong-Sian and Gazebo by Stuart Cracraft.
GNU Chess is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GNU Chess is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Chess; see the file COPYING. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
Contact Info:
bug-gnu-chess@gnu.org
cracraft@ai.mit.edu, cracraft@stanfordalumni.org, cracraft@earthlink.net
*/
/*
*
*/
#include <stdio.h>
#include "common.h"
uint32_t Rand32 (void)
/****************************************************************************
*
* A 32 bit random number generator. An implementation in C of the
* algorithm given by Knuth, the art of computer programming, vol. 2,
* pp. 26-27. We use e=32, so we have to evaluate y(n) = y(n-24) + y(n-55)
* mod 2^32, which is implicitly done by unsigned arithmetic.
*
****************************************************************************/
{
/*
* Random numbers from Mathematica 2.0
* SeedRandom = 1;
* Table[Random[Integer, {0, 2^32 - 1}]
*/
static uint32_t x[55] =
{
1410651636UL,
3012776752UL,
3497475623UL,
2892145026UL,
1571949714UL,
3253082284UL,
3489895018UL,
387949491UL,
2597396737UL,
1981903553UL,
3160251843UL,
129444464UL,
1851443344UL,
4156445905UL,
224604922UL,
1455067070UL,
3953493484UL,
1460937157UL,
2528362617UL,
317430674UL,
3229354360UL,
117491133UL,
832845075UL,
1961600170UL,
1321557429UL,
747750121UL,
545747446UL,
810476036UL,
503334515UL,
4088144633UL,
2824216555UL,
3738252341UL,
3493754131UL,
3672533954UL,
29494241UL,
1180928407UL,
4213624418UL,
33062851UL,
3221315737UL,
1145213552UL,
2957984897UL,
4078668503UL,
2262661702UL,
65478801UL,
2527208841UL,
1960622036UL,
315685891UL,
1196037864UL,
804614524UL,
1421733266UL,
2017105031UL,
3882325900UL,
810735053UL,
384606609UL,
2393861397UL
};
static int init = true;
static uint32_t y[55];
static int j, k;
uint32_t ul;
if (init)
{
int i;
init = false;
for (i = 0; i < 55; i++)
y[i] = x[i];
j = 24 - 1;
k = 55 - 1;
}
ul = (y[k] += y[j]);
if (--j < 0) j = 55 - 1;
if (--k < 0) k = 55 - 1;
return (ul);
}
HashType Rand64 (void)
{
HashType b;
b = Rand32();
b = b << 32;
b |= Rand32 ();
return (b);
}