[u-boot.git] / lib / rand.c

/*
 * Simple xorshift PRNG
 *   see http://www.jstatsoft.org/v08/i14/paper
 *
 * Copyright (c) 2012 Michael Walle
 * Michael Walle <[email protected]>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#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;
}
Commit	Line	Data
9acf1ca5 MW	1	/*
	2	* Simple xorshift PRNG
	3	* see http://www.jstatsoft.org/v08/i14/paper
	4	*
	5	* Copyright (c) 2012 Michael Walle
	6	* Michael Walle <[email protected]>
	7	*
1a459660	8	* SPDX-License-Identifier: GPL-2.0+
9acf1ca5 MW	9	*/
	10
	11	#include <common.h>
	12
	13	static unsigned int y = 1U;
	14
	15	unsigned int rand_r(unsigned int *seedp)
	16	{
	17	seedp ^= (seedp << 13);
	18	seedp ^= (seedp >> 17);
	19	seedp ^= (seedp << 5);
	20
	21	return *seedp;
	22	}
	23
	24	unsigned int rand(void)
	25	{
	26	return rand_r(&y);
	27	}
	28
	29	void srand(unsigned int seed)
	30	{
	31	y = seed;
	32	}