Pseudorandom number generator in Javascript. Algorithm from "Fast and Small Nonlinear Pseudorandom Number Generators for Computer Simulation" by Samuel Neves and Filipe Araujo.

tyche.js

function Tyche(seed, idx) {
    this.a = seed & 0xffffffff;
    this.b = (seed / ((2<<16)*(2<<16))) & 0xffffffff;
    this.c = 2654435769;
    this.d = (1367130551 ^ idx) >>> 0;
    for (var i = 20; i > 0; --i) {
        this._mix();
    }
}

function rot(x, n) {
  return (x << n | x >>> (32 - n | 0)) >>> 0;
}

Tyche.prototype._mix = function _mix() {
  this.a = (this.a + this.b | 0) >>> 0;
  this.d = rot(this.d ^ this.a, 16);
  this.c = (this.c + this.d | 0) >>> 0;
  this.b = rot(this.b ^ this.c, 12);
  this.a = (this.a + this.b | 0) >>> 0;
  this.d = rot(this.d ^ this.a, 8);
  this.c = (this.c + this.d | 0) >>> 0;
  this.b = rot(this.b ^ this.c, 7);
}

Tyche.prototype.next = function next() {
  this._mix();
  return this.b;
}

function test(ntimes) {
    var t = new Tyche(0,0);
    var d0 = new Date();
    for (var i = ntimes; i != 0; --i) {
        t.next()
    };
    var d1 = new Date();
    console.log(t.next());
    console.log(ntimes + " iterations " + (d1-d0) + "ms");
}