90 lines
2.3 KiB
JavaScript
90 lines
2.3 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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class MersenneTwister {
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constructor () {
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this.N = 624
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this.M = 397
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this.UPPER_MASK = 0x80000000
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this.LOWER_MASK = 0x7fffffff
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this.MAG01 = new Int32Array([0, 0x9908b0df])
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this.mt = new Int32Array(this.N)
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this.mti = 625 // The array for the state vector.
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}
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seed (s) {
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this.mt[0] = s | 0
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for (this.mti = 1; this.mti < this.N; this.mti++) {
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this.mt[this.mti] = Math.imul(1812433253, this.mt[this.mti - 1] ^ (this.mt[this.mti - 1] >>> 30)) + this.mti
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}
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}
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export_state () { // eslint-disable-line camelcase
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return [this.mt, this.mti]
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}
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import_state (s) { // eslint-disable-line camelcase
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this.mt = s[0]
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this.mti = s[1]
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}
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export_mta () { // eslint-disable-line camelcase
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return this.mt
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}
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import_mta (_mta) { // eslint-disable-line camelcase
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this.mt = _mta
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}
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export_mti () { // eslint-disable-line camelcase
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return this.mti
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}
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import_mti (_mti) { // eslint-disable-line camelcase
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this.mti = _mti
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}
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int32 () {
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let y, kk
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if (this.mti >= this.N) { /* generate N words at one time */
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for (kk = 0; kk < this.N - this.M; kk++) {
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y = ((this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK))
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this.mt[kk] = (this.mt[kk + this.M] ^ (y >>> 1) ^ this.MAG01[y & 0x1])
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}
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for (; kk < this.N - 1; kk++) {
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y = ((this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK))
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this.mt[kk] = (this.mt[kk + (this.M - this.N)] ^ (y >>> 1) ^ this.MAG01[y & 0x1])
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}
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y = ((this.mt[this.N - 1] & this.UPPER_MASK) | (this.mt[0] & this.LOWER_MASK))
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this.mt[this.N - 1] = (this.mt[this.M - 1] ^ (y >>> 1) ^ this.MAG01[y & 0x1])
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this.mti = 0
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}
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y = this.mt[this.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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real2 () {
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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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module.exports = MersenneTwister
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