blob: c9764f5c1a8ec12f41c047f805765445d9a05e9c [file] [log] [blame]
Michael Walle9acf1ca2012-06-05 11:33:14 +00001/*
2 * Simple xorshift PRNG
3 * see http://www.jstatsoft.org/v08/i14/paper
4 *
5 * Copyright (c) 2012 Michael Walle
6 * Michael Walle <michael@walle.cc>
7 *
8 * See file CREDITS for list of people who contributed to this
9 * project.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License as
13 * published by the Free Software Foundation; either version 2 of
14 * the License, or (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
24 * MA 02111-1307 USA
25 */
26
27#include <common.h>
28
29static unsigned int y = 1U;
30
31unsigned int rand_r(unsigned int *seedp)
32{
33 *seedp ^= (*seedp << 13);
34 *seedp ^= (*seedp >> 17);
35 *seedp ^= (*seedp << 5);
36
37 return *seedp;
38}
39
40unsigned int rand(void)
41{
42 return rand_r(&y);
43}
44
45void srand(unsigned int seed)
46{
47 y = seed;
48}