Squares RNG

This is an implementation of Bernard Widynski's counter-based PRNG as an ES6 module. The sampling is done in WASM. Relative to a pure-javascript version the WASM version is 5x-6x faster.

We use a cache and sample in blocks to reduce call overhead. When using the cache, sampling values is on par with calls to Math.random. It's faster in v8, slower in webkit. Not because webkit runs WASM slowly, but because webkit's Math.Random is 2x faster than v8. The WASM runs about the same in all engines.

TODO: perf table

Keys

Squares uses a key and a counter. The key needs an appropriate bit pattern to ensure quality output. We provide a utility method to generate a suitable key from an integer seed.

This is a low-effort key generator. There are likely to be collisions, but probably not from nearby seed values. We found no collisions within groups of 4096 sequential values for the first 1e7 integers.

Using

import { SquaresRNG, GenerateKey } from 'squares-rng';

const key = GenerateKey(123);
console.info(key.toString(16));

/**

bc8f2e15d5c8ef82

 **/

const rng = await SquaresRNG.CreateInstance(key)

for (let i = 0; i< 8; i++) {
  console.info(rng.Next().toFixed(5));
}

/**

0.80028
0.46273
0.33456
0.44465
0.71814
0.54016
0.39462
0.66978

**/

TODO: API

Reference

https://arxiv.org/pdf/2004.06278
https://squaresrng.wixsite.com/rand