Created
November 8, 2018 12:30
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PCG32 based floating point random number generation
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/** | |
* Generates a pseudorandom number, in the [0, 1[ interval. | |
* @param rng Pointer to the pseudorandom number generator. | |
*/ | |
static inline float rand_f(pcg32_random_t* rng) | |
{ | |
const uint32_t max = 1 << 24; | |
uint32_t r = pcg32_random_r(rng); | |
r &= max - 1; | |
return r * 1.0f / max; | |
} | |
/** | |
* Generates a pseudorandom number, in the [0, 1[ interval, rounded to the | |
* nearest multiple of 1/2^32. | |
* @param rng Pointer to the pseudorandom number generator. | |
*/ | |
static inline double rand_d32(pcg32_random_t* rng) | |
{ | |
union rand_double_t | |
{ | |
uint64_t u; | |
double d; | |
}; | |
union rand_double_t u = { 0x3df0000000000000 }; // ldexp(1, -32); | |
uint32_t r = pcg32_random_r(rng); | |
return (double)r * u.d; | |
} | |
/** | |
* Generates a pseudorandom number, in the [0, 1[ interval, rounded to the | |
* nearest multiple of 1/2^64. | |
* @param rng Pointer to the pseudorandom number generator. | |
*/ | |
static inline double rand_d64(pcg32_random_t* rng) | |
{ | |
union rand_double_t | |
{ | |
uint64_t u; | |
double d; | |
}; | |
union rand_double_t u = { 0x3bf0000000000000 }; // ldexp(1, -64); | |
uint64_t r = (uint64_t)pcg32_random_r(rng) << 32; | |
pcg32_random_t rng_ = *rng; | |
pcg32_random_t.inc += 2; | |
r |= pcg32_random_r(&rng_); | |
return (double)r * u.d; | |
} |
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