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Diffstat (limited to 'data/extensions/jsr@javascriptrestrictor/alea.js')
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1 files changed, 167 insertions, 0 deletions
diff --git a/data/extensions/jsr@javascriptrestrictor/alea.js b/data/extensions/jsr@javascriptrestrictor/alea.js new file mode 100644 index 0000000..50c3861 --- /dev/null +++ b/data/extensions/jsr@javascriptrestrictor/alea.js @@ -0,0 +1,167 @@ +/** \file +* \brief Random number generator +* +* A port of an algorithm by Johannes Baagøe <baagoe@baagoe.com>, 2010 and +* Tommy Ettinger (tommy.ettinger@gmail.com) +* +* Original code is available at +* http://baagoe.com/en/RandomMusings/javascript/ +* https://github.com/nquinlan/better-random-numbers-for-javascript-mirror +* https://gist.github.com/tommyettinger/46a874533244883189143505d203312c +* +* SPDX-License-Identifier: GPL-3.0-or-later +* SPDX-License-Identifier: MIT +* +* This program is free software: you can redistribute it and/or modify +* it under the terms of the GNU General Public License as published by +* the Free Software Foundation, either version 3 of the License, or +* (at your option) any later version. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU General Public License for more details. +* +* You should have received a copy of the GNU General Public License +* along with this program. If not, see <https://www.gnu.org/licenses/>. +* +* \license Original work is under MIT license and in public domain, the derived code is under GPL-3.0-or-later +*/ +// +// 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. + +/** + * alea creates a function that is functionally equivalent to Math.random. + * + * That is, successive calls of the returned function return Number values + * with positive sign, greater than or equal to 0 but less than 1, chosen + * pseudo-randomly with approximately uniform distribution over that range. + * + * The internal state of random, and hence the sequence of pseudo-random + * numbers it returns, is determined by the arguments to alea. Two functions + * returned by calls to alea with the same argument values will return exactly + * the same sequence of pseudo-random numbers. String and Number arguments + * should provide repeatable output across platforms. Object arguments[3] + * provide repeatable output on the same platform, but not necessarily on others. + * + * Please call alea() with at least one argument, the implementation with + * nno arguments described by Baagøe was not implemented here. This provides + * easy means to provide somewhat unpredictable numbers, like Math.random does. + * + * Example usage: let module_prng = alea(domainHash, "MyModuleName"); module_prng(); + * + * See more details in the README.md at + * https://github.com/nquinlan/better-random-numbers-for-javascript-mirror + */ +var alea =` +function Alea(...args) { + var mash = new Mash(); + + // Apply the seeding algorithm from Baagoe. + mash.addData(' '); + + for (var i = 0; i < args.length; i++) { + mash.addData(args[i]); + } + this.seed = mash.n | 0; // Create a 32-bit UInt + mash = null; + this.xoring = []; + for (let i = 0; i < 64; i += 8) { + this.xoring.push(parseInt(domainHash.slice(i, i+8), 16) >>> 0); // Store 32-bit unsigned integers + } +} +Alea.prototype = { + current: 0, + stored_random: 0, + random_bits: 0, + next: function() { + this.seed += 0x6D2B79F5; + var t = this.seed; + this.current = (this.current + t) & 7; + t = Math.imul(t ^ t >>> 15, t | 1); + t ^= t + Math.imul(t ^ t >>> 7, t | 61); + return (((t ^ t >>> 14) ^ this.xoring[this.current]) >>> 0); // '>>> 0' casts to unsigned + }, + normalized: function() { + return this.next() / 4294967296; + }, + get_bits: function(count) {// 0 < count <= 32 + if (count === 32) { + return this.next(); + } + else if (count <= this.random_bits) { + let mask = ((1 << count) >>> 0) - 1; + let ret = this.stored_random & mask; + this.stored_random = this.stored_random >>> count; + this.random_bits -= count; + return ret; + } + else { + let needed = count - this.random_bits; + let ret = this.stored_random << needed; + this.random_bits = 32; + this.stored_random = this.next(); + return ret | this.get_bits(needed); + } + } +} + +function impl(...seed) { + var xg = new Alea(...seed); + var prng = xg.normalized.bind(xg); + prng.uint32 = xg.next.bind(xg); + prng.fract53 = function() { + return prng() + (prng() * 0x200000 | 0) * 1.1102230246251565e-16; // 2^-53 + }; + prng.get_bits = xg.get_bits.bind(xg); + return prng; +} + +// Original at https://github.com/nquinlan/better-random-numbers-for-javascript-mirror/blob/master/support/js/Mash.js +function Mash() +{ + this.n = 0xefc8249d; +} +Mash.prototype = { + addData: function(data) { + data = String(data); + for (var i = 0; i < data.length; i++) { + this.addNumber(data.charCodeAt(i)); + } + return this; + }, + addNumber: function(num) { + this.n += num; + var h = 0.02519603282416938 * this.n; + this.n = h >>> 0; + h -= this.n; + h *= this.n; + this.n = h >>> 0; + h -= this.n; + this.n += h * 0x100000000; // 2^32 + return this; + }, + finalize: function() { + return (this.n >>> 0) * 2.3283064365386963e-10; // 2^-32 + } +} +var alea = impl; +` |