rng

rng#

Pseudo random number generators.

MWC by George Marsaglia, 1994

The MWC generator concatenates two 16-bit multiply-with-carry generators, x(n)=36969x(n-1)+carry, y(n)=18000y(n-1)+carry mod 2^16, has period about 2^60 and seems to pass all tests of randomness.

MSWS by Bernard Widynski, 2022

A variation on John von Neumann’s original middle-square method. This generator may be the fastest RNG that passes all the statistical tests. It is provided in 32 and 64 bit variants. The 32 bit variant has periodicity of 2^64. The periodicity of 64 bit variant is not documented in Widynski (2022), but it should at least be 2^64, more likely 2^128.

Ref: https://arxiv.org/abs/1704.00358

MWC by George Marsaglia, 1994

uint32_t rand_mwc()#: Return new random number using the MWC RNG.

int srand_mwc(uint32_t seed)#: Seed the rand_mws() RNG. If seed is zero, it is seeded with random_seed().

uint32_t rand_mwc_r(MWCState *state)#: Reentrant version of rand_mwc(). The internal state should always be seeded with srand_mws_r().

int srand_mwc_r(MWCState *state, uint32_t seed)#: Reentrant version of srand_mwc(). If seed is zero, it is seeded with random_seed().

MSWS by Bernard Widynski, 2022

uint32_t rand_msws32(void)#: Return new 32 bit random number using the MSWS RNG.

double drand_msws32(void)#: Return a 32-bit floating point number in the range [0,1).

int srand_msws32(uint64_t seed)#: Seed the rand_msws32() RNG. If seed is zero, it is seeded with random_seed().

uint32_t rand_msws32_r(MSWS32State *s)#: Reentrant version of rand_msws32(). Should always be seeded before use.

double drand_msws32_r(MSWS32State *s)#: Reentrant version of drand_msws32()

int srand_msws32_r(MSWS32State *s, uint64_t seed)#: Reentrant version of srand_msws32() If seed is zero, it is seeded with random_seed().

uint64_t rand_msws64(void)#: Return new 64 bit random number using the MSWS RNG.

double drand_msws64(void)#: Return a 53-bit floating point number in the range [0,1).

int srand_msws64(uint64_t seed)#: Seed the rand_msws64() RNG. If seed is zero, it is seeded with random_seed().

uint64_t rand_msws64_r(MSWS64State *s)#: Reentrant version of rand_msws64(). Should always be seeded before use.

double drand_msws64_r(MSWS64State *s)#: Reentrant version of drand_msws64(). Should always be seeded before use.

int srand_msws64_r(MSWS64State *s, uint64_t seed)#: Reentrant version of srand_msws64() If seed is zero, it is seeded with random_seed().

Functions

int random_seed(void *buf, size_t size)#

Ask system to write size random bytes to buf.

This function is intended to be used to seed the RNGs. It is called when the seed functions are called with seed=0.

It tries first to use the system random source. If that doesn’t work and macro RNG_ONLY_HIGH_QUALITY_SEED is not defined, it falls back to using the system clock.

Returns non-zero on error.

struct MWCState#

#include <rng.h>

Internal state of the MWC RNG.

Public Members

uint32_t mwc_upper#

uint32_t mwc_lower#

struct MSWS32State#

#include <rng.h>

Internal state of the MSWS32 RNG.

Public Members

uint64_t x#

uint64_t w#

uint64_t s#

struct MSWS64State#

#include <rng.h>

Internal state of the MSWS64 RNG.

Public Members

uint64_t x1#

uint64_t w1#

uint64_t s1#

uint64_t x2#

uint64_t w2#

uint64_t s2#

rng

Contents

rng#