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galaxygen/MersenneTwister.js
Bram van der Veen 3a8803318b Updated the code to the new version found on loewald.com/galaxygen
(after some heavy refactoring)
2017-01-24 19:56:57 +01:00

124 lines
3.5 KiB
JavaScript

class MersenneTwister {
constructor(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);
};
init_genrand(s) {
this.mt[0] = s >>> 0;
for (this.mti = 1; this.mti < this.N; this.mti++) {
let 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;
}
}
init_by_array(init_key, key_length) {
let i, j, k;
this.init_genrand(19650218);
i = 1;
j = 0;
k = (this.N > key_length ? this.N : key_length);
for (; k; k--) {
let 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--) {
let 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;
}
genrand_int32() {
let y;
let mag01 = new Array(0x0, this.MATRIX_A);
if (this.mti >= this.N) {
let 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;
}
genrand_int31() {
return (this.genrand_int32() >>> 1);
}
genrand_real1() {
return this.genrand_int32() * (1.0 / 4294967295.0);
}
random() {
return this.genrand_int32() * (1.0 / 4294967296.0);
}
genrand_real3() {
return (this.genrand_int32() + 0.5) * (1.0 / 4294967296.0);
}
genrand_res53() {
let a = this.genrand_int32() >>> 5,
b = this.genrand_int32() >>> 6;
return (a * 67108864.0 + b) * (1.0 / 9007199254740992.0);
}
}
module.exports = MersenneTwister;