[fio.git] / lib / rand.h

#ifndef FIO_RAND_H
#define FIO_RAND_H

struct frand_state {
	unsigned int s1, s2, s3;
};

extern struct frand_state __fio_rand_state;

static inline unsigned int __rand(struct frand_state *state)
{
#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)

	state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12);
	state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
	state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);

	return (state->s1 ^ state->s2 ^ state->s3);
}

extern void init_rand(struct frand_state *);

#endif
Commit	Line	Data
1fbbf72e JA	1	#ifndef FIO_RAND_H
	2	#define FIO_RAND_H
	3
	4	struct frand_state {
	5	unsigned int s1, s2, s3;
	6	};
	7
	8	extern struct frand_state __fio_rand_state;
	9
	10	static inline unsigned int __rand(struct frand_state *state)
	11	{
	12	#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
	13
	14	state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12);
	15	state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
	16	state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);
	17
	18	return (state->s1 ^ state->s2 ^ state->s3);
	19	}
	20
	21	extern void init_rand(struct frand_state *);
	22
	23	#endif