galaxygen/twister.js

var MersenneTwister = function(seed) {
    if (seed == undefined) {
        seed = new Date().getTime();
    }
    this.N = 624;
    this.M = 397;
    this.MATRIX_A = 0x9908b0df;
    this.UPPER_MASK = 0x80000000;
    this.LOWER_MASK = 0x7fffffff;
    this.mt = new Array(this.N);
    this.mti = this.N + 1;
    this.init_genrand(seed);
}

MersenneTwister.prototype.init_genrand = function(s) {
    this.mt[0] = s >>> 0;
    for (this.mti = 1; this.mti < this.N; this.mti++) {
        var s = this.mt[this.mti - 1] ^ (this.mt[this.mti - 1] >>> 30);
        this.mt[this.mti] = (((((s & 0xffff0000) >>> 16) * 1812433253) << 16) + (s & 0x0000ffff) * 1812433253) +
            this.mti;
        this.mt[this.mti] >>>= 0;
    }
}

MersenneTwister.prototype.init_by_array = function(init_key, key_length) {
    var i, j, k;
    this.init_genrand(19650218);
    i = 1;
    j = 0;
    k = (this.N > key_length ? this.N : key_length);
    for (; k; k--) {
        var s = this.mt[i - 1] ^ (this.mt[i - 1] >>> 30)
        this.mt[i] = (this.mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1664525) << 16) + ((s & 0x0000ffff) * 1664525))) +
            init_key[j] + j;
        this.mt[i] >>>= 0;
        i++;
        j++;
        if (i >= this.N) {
            this.mt[0] = this.mt[this.N - 1];
            i = 1;
        }
        if (j >= key_length) j = 0;
    }
    for (k = this.N - 1; k; k--) {
        var s = this.mt[i - 1] ^ (this.mt[i - 1] >>> 30);
        this.mt[i] = (this.mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1566083941) << 16) + (s & 0x0000ffff) * 1566083941)) -
            i;
        this.mt[i] >>>= 0;
        i++;
        if (i >= this.N) {
            this.mt[0] = this.mt[this.N - 1];
            i = 1;
        }
    }
    this.mt[0] = 0x80000000;
}

MersenneTwister.prototype.genrand_int32 = function() {
    var y;
    var mag01 = new Array(0x0, this.MATRIX_A);
    if (this.mti >= this.N) {
        var kk;
        if (this.mti == this.N + 1)
            this.init_genrand(5489);
        for (kk = 0; kk < this.N - this.M; kk++) {
            y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK);
            this.mt[kk] = this.mt[kk + this.M] ^ (y >>> 1) ^ mag01[y & 0x1];
        }
        for (; kk < this.N - 1; kk++) {
            y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK);
            this.mt[kk] = this.mt[kk + (this.M - this.N)] ^ (y >>> 1) ^ mag01[y & 0x1];
        }
        y = (this.mt[this.N - 1] & this.UPPER_MASK) | (this.mt[0] & this.LOWER_MASK);
        this.mt[this.N - 1] = this.mt[this.M - 1] ^ (y >>> 1) ^ mag01[y & 0x1];
        this.mti = 0;
    }
    y = this.mt[this.mti++];
    y ^= (y >>> 11);
    y ^= (y << 7) & 0x9d2c5680;
    y ^= (y << 15) & 0xefc60000;
    y ^= (y >>> 18);
    return y >>> 0;
}

MersenneTwister.prototype.genrand_int31 = function() {
    return (this.genrand_int32() >>> 1);
}

MersenneTwister.prototype.genrand_real1 = function() {
    return this.genrand_int32() * (1.0 / 4294967295.0);
}

MersenneTwister.prototype.random = function() {
    return this.genrand_int32() * (1.0 / 4294967296.0);
}

MersenneTwister.prototype.genrand_real3 = function() {
    return (this.genrand_int32() + 0.5) * (1.0 / 4294967296.0);
}

MersenneTwister.prototype.genrand_res53 = function() {
    var a = this.genrand_int32() >>> 5,
        b = this.genrand_int32() >>> 6;
    return (a * 67108864.0 + b) * (1.0 / 9007199254740992.0);
}

module.exports = MersenneTwister;