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Added a version of xoroshiro128+

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Heng Li 2018-08-30 23:05:18 -10:00
parent fd1bf6d3f0
commit 16d3b1189f
1 changed files with 54 additions and 0 deletions
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krng.h Normal file
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#ifndef KRNG_H
#define KRNG_H
typedef struct {
uint64_t s[2];
} krng_t;
static inline uint64_t kr_splitmix64(uint64_t x)
{
uint64_t z = (x += 0x9E3779B97F4A7C15ULL);
z = (z ^ (z >> 30)) * 0xBF58476D1CE4E5B9ULL;
z = (z ^ (z >> 27)) * 0x94D049BB133111EBULL;
return z ^ (z >> 31);
}
static inline uint64_t kr_rand_r(krng_t *r)
{
const uint64_t s0 = r->s[0];
uint64_t s1 = r->s[1];
const uint64_t result = s0 + s1;
s1 ^= s0;
r->s[0] = (s0 << 55 | s0 >> 9) ^ s1 ^ (s1 << 14);
r->s[1] = s0 << 36 | s0 >> 28;
return result;
}
static inline void kr_jump_r(krng_t *r)
{
static const uint64_t JUMP[] = { 0xbeac0467eba5facbULL, 0xd86b048b86aa9922ULL };
uint64_t s0 = 0, s1 = 0;
int i, b;
for (i = 0; i < 2; ++i)
for (b = 0; b < 64; b++) {
if (JUMP[i] & 1ULL << b)
s0 ^= r->s[0], s1 ^= r->s[1];
kr_rand_r(r);
}
r->s[0] = s0, r->s[1] = s1;
}
static inline void kr_srand_r(krng_t *r, uint64_t seed)
{
r->s[0] = kr_splitmix64(seed);
r->s[1] = kr_splitmix64(r->s[0]);
}
static inline double kr_drand_r(krng_t *r)
{
union { uint64_t i; double d; } u;
u.i = 0x3FFULL << 52 | kr_rand_r(r) >> 12;
return u.d - 1.0;
}
#endif