alea.js

(function (root, factory) {
  if (typeof exports === 'object') {
      module.exports = factory();
  } else if (typeof define === 'function' && define.amd) {
      define(factory);
  } else {
      root.Alea = factory();
  }
}(this, function () {

  'use strict';

  // From http://baagoe.com/en/RandomMusings/javascript/

  // importState to sync generator states
  Alea.importState = function(i){
    var random = new Alea();
    random.importState(i);
    return random;
  };

  return Alea;

  function Alea() {
    return (function(args) {
      // Johannes Baagøe <baagoe@baagoe.com>, 2010
      var s0 = 0;
      var s1 = 0;
      var s2 = 0;
      var c = 1;

      if (args.length == 0) {
        args = [+new Date];
      }
      var mash = Mash();
      s0 = mash(' ');
      s1 = mash(' ');
      s2 = mash(' ');

      for (var i = 0; i < args.length; i++) {
        s0 -= mash(args[i]);
        if (s0 < 0) {
          s0 += 1;
        }
        s1 -= mash(args[i]);
        if (s1 < 0) {
          s1 += 1;
        }
        s2 -= mash(args[i]);
        if (s2 < 0) {
          s2 += 1;
        }
      }
      mash = null;

      var random = function() {
        var t = 2091639 * s0 + c * 2.3283064365386963e-10; // 2^-32
        s0 = s1;
        s1 = s2;
        return s2 = t - (c = t | 0);
      };
      random.next = random;
      random.uint32 = function() {
        return random() * 0x100000000; // 2^32
      };
      random.fract53 = function() {
        return random() + 
          (random() * 0x200000 | 0) * 1.1102230246251565e-16; // 2^-53
      };
      random.version = 'Alea 0.9';
      random.args = args;

      // my own additions to sync state between two generators
      random.exportState = function(){
        return [s0, s1, s2, c];
      };
      random.importState = function(i){
        s0 = +i[0] || 0;
        s1 = +i[1] || 0;
        s2 = +i[2] || 0;
        c = +i[3] || 0;
      };
 
      return random;

    } (Array.prototype.slice.call(arguments)));
  }

  function Mash() {
    var n = 0xefc8249d;

    var mash = function(data) {
      data = data.toString();
      for (var i = 0; i < data.length; i++) {
        n += data.charCodeAt(i);
        var h = 0.02519603282416938 * n;
        n = h >>> 0;
        h -= n;
        h *= n;
        n = h >>> 0;
        h -= n;
        n += h * 0x100000000; // 2^32
      }
      return (n >>> 0) * 2.3283064365386963e-10; // 2^-32
    };

    mash.version = 'Mash 0.9';
    return mash;
  }
}));