js-2dmath/lib/xorshift.js

Fast 2d geometry math: Vector2, Rectangle, Circle, Matrix2x3 (2D transformation), Circle, BoundingBox, Line2, Segment2, Intersections, Distances, Transitions (animation/tween), Random numbers, Noise

// from: http://jsdo.it/akm2/fhMC/js
// don't know the author :)
// I just lint the code... and adapt it to this lib philosophy

// Helper

function _mash(data) {
    data = data.toString();
    var n = 0xefc8249d,
        i,
        len,
        h;

    for (i = 0, len = data.length; i < len; i++) {
        n += data.charCodeAt(i);
        h = 0.02519603282416938 * n;
        n = h >>> 0;
        h -= n;
        h *= n;
        n = h >>> 0;
        h -= n;
        n += h * 0x100000000;
    }
    return (n >>> 0) * 2.3283064365386963e-10;
}

/**
 * Random numbers generator
 * Returns an object with three methods
 * * uint32()
 * * random()
 * * fract53()
 *
 * @see http://baagoe.com/en/RandomMusings/javascript/
 * @see http://en.wikipedia.org/wiki/Xorshift
 * @source http://jsdo.it/akm2/fhMC/js
 *
 * @param {Array} seeds
 * @return {Object} {uint32: Function, random: Function, fract53: Function}
 */
function create(seeds) {
    var self = this,
        seeds = (arguments.length) ? Array.prototype.slice.call(arguments) : [new Date().getTime()],

        x = 123456789,
        y = 362436069,
        z = 521288629,
        w = 88675123,
        v = 886756453,
        i,
        len,
        seed,
        t;

    for (i = 0, len = seeds.length; i < len; i++) {
        seed = seeds[i];
        x ^= _mash(seed) * 0x100000000;
        y ^= _mash(seed) * 0x100000000;
        z ^= _mash(seed) * 0x100000000;
        v ^= _mash(seed) * 0x100000000;
        w ^= _mash(seed) * 0x100000000;
    }

    return {
        uint32: function () {
            t = (x ^ (x >>> 7)) >>> 0;
            x = y;
            y = z;
            z = w;
            w = v;
            v = (v ^ (v << 6)) ^ (t ^ (t << 13)) >>> 0;
            return ((y + y + 1) * v) >>> 0;
        },

        random: function () {
            return self.uint32() * 2.3283064365386963e-10;
        },

        fract53: function () {
            return self.random() + (self.uint32() & 0x1fffff) * 1.1102230246251565e-16;
        }
    };
};

Xorshift = {
    create: create
};

module.exports = Xorshift;