};
-typedef struct {
- u32b dw[2];
-} u64b;
-
-static u64b u64b_xor(u64b a, u64b b)
-{
- u64b result;
-
- result.dw[0] = a.dw[0] ^ b.dw[0];
- result.dw[1] = a.dw[1] ^ b.dw[1];
-
- return result;
-}
-
-static u64b u64b_shiftl(u64b x, int k)
-{
- u64b result;
-
- if (k < 32) {
- result.dw[1] = (x.dw[1] << k) | (x.dw[0] >> (32 - k));
- result.dw[0] = (x.dw[0] << k);
- }
- else {
- result.dw[1] = (x.dw[0] << (k - 32));
- result.dw[0] = 0;
- }
-
- return result;
-}
-
-static u64b u64b_rotl(u64b x, int k)
-{
- u64b result;
-
- if (k < 32) {
- result.dw[0] = (x.dw[0] << k) | (x.dw[1] >> (32 - k));
- result.dw[1] = (x.dw[1] << k) | (x.dw[0] >> (32 - k));
- }
- else {
- result.dw[0] = (x.dw[0] >> (64 - k)) | (x.dw[1] << (k - 32));
- result.dw[1] = (x.dw[1] >> (64 - k)) | (x.dw[0] << (k - 32));
- }
-
- return result;
-}
-
-static u64b u64b_add(u64b a, u64b b)
+static u32b u32b_rotl(const u32b x, int k)
{
- u64b result;
-
- result.dw[0] = a.dw[0] + b.dw[0];
- result.dw[1] = a.dw[1] + b.dw[1];
-
- if (result.dw[0] < a.dw[0])
- result.dw[1] ++;
-
- return result;
+ return (x << k) | (x >> (32 - k));
}
/*
- * Initialize Xorshift Algorithm state
+ * Initialize RNG state
*/
-static void Rand_Xorshift_seed(u32b seed, u32b* state)
+static void Rand_seed(u32b seed, u32b* state)
{
int i;
- /* Initialize Xorshift Algorithm RNG */
for (i = 1; i <= 4; ++ i) {
seed = 1812433253UL * (seed ^ (seed >> 30)) + i;
state[i-1] = seed;
}
}
-#if 0
/*
- * Xorshift Algorithm
+ * Xoshiro128** Algorithm
*/
-static u32b Rand_Xorshift(u32b* state)
+static u32b Rand_Xoshiro128starstar(u32b *state)
{
- u32b t = state[0] ^ (state[0] << 11);
-
- state[0] = state[1];
- state[1] = state[2];
- state[2] = state[3];
+ const u32b result = u32b_rotl(state[0] * 5, 7) * 9;
- state[3] = (state[3] ^ (state[3] >> 19)) ^ (t ^ (t >> 8));
+ const u32b t = state[1] << 9;
- return state[3];
-}
-#endif
+ state[2] ^= state[0];
+ state[3] ^= state[1];
+ state[1] ^= state[2];
+ state[0] ^= state[3];
-/*
- * Xoroshiro128+ Algorithm
- */
-static u32b Rand_Xoroshiro128plus(u32b* state)
-{
- const u64b s0 = *((u64b*)state);
- u64b s1 = *((u64b*)state + 1);
- const u64b result = u64b_add(s0, s1);
+ state[2] ^= t;
- s1 = u64b_xor(s0, s1);
- *((u64b*)state) = u64b_xor(u64b_xor(u64b_rotl(s0, 55), s1), u64b_shiftl(s1, 14));
- *((u64b*)state + 1) = u64b_rotl(s1, 36);
+ state[3] = u32b_rotl(state[3], 11);
- return result.dw[0];
+ return result;
}
static const u32b Rand_Xorshift_max = 0xFFFFFFFF;
*/
void Rand_state_set(u32b seed)
{
- Rand_Xorshift_seed(seed, Rand_state);
+ Rand_seed(seed, Rand_state);
}
void Rand_state_init(void)
past = scaling * m;
do {
- ret = Rand_Xoroshiro128plus(state);
+ ret = Rand_Xoshiro128starstar(state);
} while (ret >= past);
return ret / scaling;
{
/* Initialize with new seed */
u32b seed = (u32b)time(NULL);
- Rand_Xorshift_seed(seed, Rand_state_external);
+ Rand_seed(seed, Rand_state_external);
initialized = TRUE;
}