portable-rng/index.js

Simple, node/browser compatible Alea RNG generator from http://baagoe.com/en/RandomMusings/javascript/

(function(){
'use strict';
	
	// From http://baagoe.com/en/RandomMusings/javascript/
	// Johannes Baagøe <baagoe@baagoe.com>, 2010
	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;
	}

	// From http://baagoe.com/en/RandomMusings/javascript/
	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.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;
			return random;
		}(Array.prototype.slice.call(arguments)));
	}


	function createRng() {
		return Alea.apply(Alea, arguments);
	}

	// export in common js
	if( typeof module !== "undefined" && ('exports' in module)){
		module.exports = createRng;
		module.exports.Mash = Mash;
		module.exports.Alea = Alea;
		module.exports['portable-rng'] = createRng;
	}

})();