//The following RNG is based on code for the xorshift* RNG by Sebastiano Vigna
//Parameters are chosen from the original paper such to

typedef struct
{
    uint64_t w, x;
} XorShift128rm_state;

const uint64_t p1 = 0x243f6a8885a308d3;
const uint64_t p2 = 0x13198a2e03707345;

static uint64_t rotl(uint64_t x, uint8_t r)
{
    return (x << r) | (x >> (64-r));
}

uint64_t XorShift128rm(XorShift128rm_state *s)
{
    uint64_t t = s->w;
    s->w = s->x;
    s->x = t;

    s->x ^= s->x << 16;
    s->x ^= (s->x >> 21) ^ s->w ^ (s->w >> 1);

    return rotl(s->x*p1, 16)*p2;
}