70 lines
2.9 KiB
JavaScript
70 lines
2.9 KiB
JavaScript
var MersenneTwister = (function () {
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function MersenneTwister(states, index) {
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this.states = states;
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this.index = index;
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}
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MersenneTwister.twist = function (prev) {
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var mt = prev.slice();
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for (var idx = 0; idx !== MersenneTwister.N - MersenneTwister.M; ++idx) {
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var y_1 = (mt[idx] & MersenneTwister.MASK_UPPER) + (mt[idx + 1] & MersenneTwister.MASK_LOWER);
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mt[idx] = mt[idx + MersenneTwister.M] ^ (y_1 >>> 1) ^ (-(y_1 & 1) & MersenneTwister.A);
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}
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for (var idx = MersenneTwister.N - MersenneTwister.M; idx !== MersenneTwister.N - 1; ++idx) {
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var y_2 = (mt[idx] & MersenneTwister.MASK_UPPER) + (mt[idx + 1] & MersenneTwister.MASK_LOWER);
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mt[idx] = mt[idx + MersenneTwister.M - MersenneTwister.N] ^ (y_2 >>> 1) ^ (-(y_2 & 1) & MersenneTwister.A);
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}
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var y = (mt[MersenneTwister.N - 1] & MersenneTwister.MASK_UPPER) + (mt[0] & MersenneTwister.MASK_LOWER);
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mt[MersenneTwister.N - 1] = mt[MersenneTwister.M - 1] ^ (y >>> 1) ^ (-(y & 1) & MersenneTwister.A);
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return mt;
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};
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MersenneTwister.seeded = function (seed) {
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var out = Array(MersenneTwister.N);
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out[0] = seed;
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for (var idx = 1; idx !== MersenneTwister.N; ++idx) {
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var xored = out[idx - 1] ^ (out[idx - 1] >>> 30);
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out[idx] = (Math.imul(MersenneTwister.F, xored) + idx) | 0;
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}
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return out;
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};
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MersenneTwister.from = function (seed) {
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return new MersenneTwister(MersenneTwister.twist(MersenneTwister.seeded(seed)), 0);
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};
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MersenneTwister.prototype.clone = function () {
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return new MersenneTwister(this.states, this.index);
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};
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MersenneTwister.prototype.next = function () {
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var nextRng = new MersenneTwister(this.states, this.index);
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var out = nextRng.unsafeNext();
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return [out, nextRng];
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};
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MersenneTwister.prototype.unsafeNext = function () {
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var y = this.states[this.index];
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y ^= this.states[this.index] >>> MersenneTwister.U;
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y ^= (y << MersenneTwister.S) & MersenneTwister.B;
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y ^= (y << MersenneTwister.T) & MersenneTwister.C;
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y ^= y >>> MersenneTwister.L;
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if (++this.index >= MersenneTwister.N) {
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this.states = MersenneTwister.twist(this.states);
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this.index = 0;
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}
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return y;
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};
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MersenneTwister.N = 624;
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MersenneTwister.M = 397;
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MersenneTwister.R = 31;
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MersenneTwister.A = 0x9908b0df;
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MersenneTwister.F = 1812433253;
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MersenneTwister.U = 11;
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MersenneTwister.S = 7;
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MersenneTwister.B = 0x9d2c5680;
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MersenneTwister.T = 15;
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MersenneTwister.C = 0xefc60000;
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MersenneTwister.L = 18;
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MersenneTwister.MASK_LOWER = Math.pow(2, MersenneTwister.R) - 1;
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MersenneTwister.MASK_UPPER = Math.pow(2, MersenneTwister.R);
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return MersenneTwister;
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}());
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export default function (seed) {
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return MersenneTwister.from(seed);
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}
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