86 lines
2 KiB
JavaScript
86 lines
2 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* JavaScript version of Mersenne Twister
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*
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* @author Yasuharu Okada
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*
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*/
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function MersenneTwister() {
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const N = 624;
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const M = 397;
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const UPPER_MASK = 0x80000000;
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const LOWER_MASK = 0x7fffffff;
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const MAG01 = new Int32Array([0, 0x9908b0df]);
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let mt = new Int32Array(N);
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/* the array for the state vector */
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let mti = 625;
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this.seed = function (s) {
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mt[0] = s | 0;
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for (mti = 1; mti < N; mti++) {
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mt[mti] = Math.imul(1812433253, mt[mti - 1] ^ (mt[mti - 1] >>> 30)) + mti;
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}
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};
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this.export_state = function () {
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return [mt, mti];
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};
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this.import_state = function (s) {
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mt = s[0];
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mti = s[1];
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};
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this.export_mta = function () {
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return mt;
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};
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this.import_mta = function (_mta) {
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mt = _mta;
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};
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this.export_mti = function () {
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return mti;
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};
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this.import_mti = function (_mti) {
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mti = _mti;
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};
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this.int32 = function () {
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let y, kk;
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if (mti >= N) { /* generate N words at one time */
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for (kk = 0; kk < N - M; kk++) {
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y = ((mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK));
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mt[kk] = (mt[kk + M] ^ (y >>> 1) ^ MAG01[y & 0x1]);
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}
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for (; kk < N - 1; kk++) {
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y = ((mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK));
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mt[kk] = (mt[kk + (M - N)] ^ (y >>> 1) ^ MAG01[y & 0x1]);
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}
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y = ((mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK));
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mt[N - 1] = (mt[M - 1] ^ (y >>> 1) ^ MAG01[y & 0x1]);
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mti = 0;
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}
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y = mt[mti++];
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/* Tempering */
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y = y ^ (y >>> 11);
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y = y ^ ((y << 7) & 0x9d2c5680);
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y = y ^ ((y << 15) & 0xefc60000);
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y = y ^ (y >>> 18);
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return y >>> 0;
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};
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this.real2 = function () {
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return ((this.int32() >>> 5) * 67108864.0 + (this.int32() >>> 6)) / 9007199254740992.0;
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};
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}
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