rand.c

/*
 * Simple xorshift PRNG
 *   see http://www.jstatsoft.org/v08/i14/paper
 *
 * Copyright (c) 2012 Michael Walle
 * Michael Walle <michael@walle.cc>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program 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 of
 * the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>

static unsigned int y = 1U;

unsigned int rand_r(unsigned int *seedp)
{
	*seedp ^= (*seedp << 13);
	*seedp ^= (*seedp >> 17);
	*seedp ^= (*seedp << 5);

	return *seedp;
}

unsigned int rand(void)
{
	return rand_r(&y);
}

void srand(unsigned int seed)
{
	y = seed;
}