sys/base/rng/random.c


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#include "internal.h"

static uint64
xoshiro256ss(Rng *state)
{
    uint64 *s     = state->s;
    uint64 result = rol64(s[1] * 5, 7) * 9;
    uint64 t      = s[1] << 17;

    s[2] ^= s[0];
    s[3] ^= s[1];
    s[1] ^= s[2];
    s[0] ^= s[3];

    s[2] ^= t;
    s[3] = rol64(s[3], 45);

    return result;
}

double
rng·random(void)
{
    uint64 r = xoshiro256ss(&rng·RNG);
    return (double)r / (double)UINT64_MAX;
}

uint64
rng·randi(int max)
{
    uint64 r = xoshiro256ss(&rng·RNG);
    return r % max;
}