Random.c

#include <ctype.h>
#include <inttypes.h>
#include "Random.h"


/* PCG RANDOM NUMBER GENERTOR FUNCTIONS: */

inline void pcg_setseq_64_step_r(struct pcg32_random_t* rng)
{
    rng->state = rng->state * PCG_DEFAULT_MULTIPLIER_64 + rng->inc;
}

inline uint32_t pcg_output_xsh_rr_64_32(uint64_t state)
{
    return pcg_rotr_32(((state >> 18u) ^ state) >> 27u, state >> 59u);
}

inline uint32_t pcg_rotr_32(uint32_t value, unsigned int rot)
{
    return (value >> rot) | (value << ((- rot) & 31));
}

inline void pcg32_srandom_r(struct pcg32_random_t* rng,
                                    uint64_t initstate, uint64_t initseq)
{
    rng->state = 0U;
    rng->inc = (initseq << 1u) | 1u;
    pcg_setseq_64_step_r(rng);
    rng->state += initstate;
    pcg_setseq_64_step_r(rng);
}

inline uint32_t pcg32_random_r(struct pcg32_random_t* rng)
{
    uint64_t oldstate = rng->state;
    pcg_setseq_64_step_r(rng);
    return pcg_output_xsh_rr_64_32(oldstate);
}

inline uint32_t	pcg32_boundedrand_r(struct pcg32_random_t* rng, uint32_t bound)
	{
	    uint32_t threshold = -bound % bound;
	    for (;;) {
			uint32_t r = pcg32_random_r(rng);
		if (r >= threshold)
		    return r % bound;
	    }
}