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115 lines
3.2 KiB
115 lines
3.2 KiB
// A port of an algorithm by Johannes Baagøe <baagoe@baagoe.com>, 2010
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// http://baagoe.com/en/RandomMusings/javascript/
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// https://github.com/nquinlan/better-random-numbers-for-javascript-mirror
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// Original work is under MIT license -
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// Copyright (C) 2010 by Johannes Baagøe <baagoe@baagoe.org>
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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(function(global, module, define) {
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function Alea(seed) {
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var me = this, mash = Mash();
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me.next = function() {
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var t = 2091639 * me.s0 + me.c * 2.3283064365386963e-10; // 2^-32
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me.s0 = me.s1;
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me.s1 = me.s2;
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return me.s2 = t - (me.c = t | 0);
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};
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// Apply the seeding algorithm from Baagoe.
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me.c = 1;
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me.s0 = mash(' ');
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me.s1 = mash(' ');
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me.s2 = mash(' ');
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me.s0 -= mash(seed);
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if (me.s0 < 0) { me.s0 += 1; }
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me.s1 -= mash(seed);
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if (me.s1 < 0) { me.s1 += 1; }
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me.s2 -= mash(seed);
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if (me.s2 < 0) { me.s2 += 1; }
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mash = null;
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}
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function copy(f, t) {
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t.c = f.c;
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t.s0 = f.s0;
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t.s1 = f.s1;
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t.s2 = f.s2;
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return t;
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}
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function impl(seed, opts) {
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var xg = new Alea(seed),
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state = opts && opts.state,
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prng = xg.next;
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prng.int32 = function() { return (xg.next() * 0x100000000) | 0; }
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prng.double = function() {
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return prng() + (prng() * 0x200000 | 0) * 1.1102230246251565e-16; // 2^-53
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};
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prng.quick = prng;
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if (state) {
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if (typeof(state) == 'object') copy(state, xg);
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prng.state = function() { return copy(xg, {}); }
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}
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return prng;
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}
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function Mash() {
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var n = 0xefc8249d;
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var mash = function(data) {
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data = String(data);
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for (var i = 0; i < data.length; i++) {
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n += data.charCodeAt(i);
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var h = 0.02519603282416938 * n;
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n = h >>> 0;
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h -= n;
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h *= n;
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n = h >>> 0;
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h -= n;
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n += h * 0x100000000; // 2^32
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}
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return (n >>> 0) * 2.3283064365386963e-10; // 2^-32
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};
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return mash;
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}
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if (module && module.exports) {
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module.exports = impl;
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} else if (define && define.amd) {
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define(function() { return impl; });
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} else {
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this.alea = impl;
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}
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})(
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this,
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(typeof module) == 'object' && module, // present in node.js
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(typeof define) == 'function' && define // present with an AMD loader
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);
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