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- // A port of an algorithm by Johannes Baagøe <baagoe@baagoe.com>, 2010
- // http://baagoe.com/en/RandomMusings/javascript/
- // https://github.com/nquinlan/better-random-numbers-for-javascript-mirror
- // Original work is under MIT license -
- // Copyright (C) 2010 by Johannes Baagøe <baagoe@baagoe.org>
- //
- // Permission is hereby granted, free of charge, to any person obtaining a copy
- // of this software and associated documentation files (the "Software"), to deal
- // in the Software without restriction, including without limitation the rights
- // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- // copies of the Software, and to permit persons to whom the Software is
- // furnished to do so, subject to the following conditions:
- //
- // The above copyright notice and this permission notice shall be included in
- // all copies or substantial portions of the Software.
- //
- // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- // THE SOFTWARE.
- (function(global, module, define) {
- function Alea(seed) {
- var me = this, mash = Mash();
- me.next = function() {
- var t = 2091639 * me.s0 + me.c * 2.3283064365386963e-10; // 2^-32
- me.s0 = me.s1;
- me.s1 = me.s2;
- return me.s2 = t - (me.c = t | 0);
- };
- // Apply the seeding algorithm from Baagoe.
- me.c = 1;
- me.s0 = mash(' ');
- me.s1 = mash(' ');
- me.s2 = mash(' ');
- me.s0 -= mash(seed);
- if (me.s0 < 0) { me.s0 += 1; }
- me.s1 -= mash(seed);
- if (me.s1 < 0) { me.s1 += 1; }
- me.s2 -= mash(seed);
- if (me.s2 < 0) { me.s2 += 1; }
- mash = null;
- }
- function copy(f, t) {
- t.c = f.c;
- t.s0 = f.s0;
- t.s1 = f.s1;
- t.s2 = f.s2;
- return t;
- }
- function impl(seed, opts) {
- var xg = new Alea(seed),
- state = opts && opts.state,
- prng = xg.next;
- prng.int32 = function() { return (xg.next() * 0x100000000) | 0; }
- prng.double = function() {
- return prng() + (prng() * 0x200000 | 0) * 1.1102230246251565e-16; // 2^-53
- };
- prng.quick = prng;
- if (state) {
- if (typeof(state) == 'object') copy(state, xg);
- prng.state = function() { return copy(xg, {}); }
- }
- return prng;
- }
- 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
- };
- return mash;
- }
- if (module && module.exports) {
- module.exports = impl;
- } else if (define && define.amd) {
- define(function() { return impl; });
- } else {
- this.alea = impl;
- }
- })(
- this,
- (typeof module) == 'object' && module, // present in node.js
- (typeof define) == 'function' && define // present with an AMD loader
- );
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