pcg.h

Single header, 100 line implementation of 32bit PCG random number generator.

Advantages

• Blazing fast generation of uint32 and 32bit floats in [0,1)

• Each rng class instance only takes 128bits of memory (two uint64)

Disadvantages

Doesn't conform to full C++11 rng engine requirements. It's a very simple rng that produces output fast.

API

Constructor

• Based on nanosecond clock and thread id

• Should guarantee different rng values in most usecases

  • You can also manually seed by providing two uint64_t
  • The first being the seed, second the sequence id

Generating rng values

• next() generates a uniformly distributed uint32_t

• next_bounded(uint32_t) generates a bounded uint32_t (exclusive)

• next_float() generates a float in [0,1)

Requires C++11 for default seeding. Specifically <thread> and <chrono>.

Example

#include "pcg.h"

int main() {
    // Create new instance of RNG
    // Default seed is different for all threads and nanosecond-time based
    pcg::pcg32 rng;

    for (int i = 0; i < 99; ++i) {
        std::cout << rng.next() << std::endl;
        std::cout << rng.next_float() << std::endl;
        std::cout << rng.next_bounded(101) << std::endl;
    }

    return 0;
 }