MWC Pseudo-Random Number Generator

This is a re-implementation of the Multiply With Carry Pseudo-Random Number Generator as described by its wikipedia page.

Parameters are kept the same, however this implementation differs by providing a pure API on the random functions in a single .h file and allowing the initial random generator function to be defined by the user.

API

This random number generator is split in 4 functions. All of them are pure except for the mwc_create().

mwc_create(): creates the mwc_random_t data type, this is not a pure method because it makes use of the MWC_SYSTEM_RAND32 function.
mwc_init(): initializes the created mwc_random_t with the startup values
mwc_read_random(state): returns the random value (uint32_t), this is a pure method, it always produces the same random number if the state is not advanced by the mwc_next_random()
mwc_next_random(state): creates a new state with another random value that can then be read by the mwc_read_random()

Example Usage

#include "mwc.h"

// Create and initialize the `mwc_random_t` struct
mwc_random_t rnd = mwc_init(mwc_create());

// Pure API, `mwc_read_random()` will not change the `mwc_random_t`
// and always produces the same value.
uint32_t value1 = mwc_read_random(rnd);
// To create a new `mwc_random_t` state, pass the previous state to
// the `mwc_next_random()` function
rnd = mwc_next_random(rnd);

uint32_t value2 = mwc_read_random(rnd);
rnd = mwc_next_random(rnd);

uint32_t value3 = mwc_read_random(rnd);

The mwc_create() makes use of the system rand function, by default it uses the arc4random() from <stdlib.h> (available in BSDs/macOS). If your system does not have this function or if you want to supply your own seed initialization function please define the MWC_SYSTEM_RAND32 preprocessor value to match your function.

Here is an example

// Defining the system random function used to create the seed array
uint32_t my_rand(void) {
  return 4;
}

#define MWC_SYSTEM_RAND32 my_rand
#include "mwc.h"

HugoDaniel/mwc

MWC Pseudo-Random Number Generator

API

Example Usage