octo-deno/lib/random/mersennetwister.ts

107 lines
2.4 KiB
TypeScript

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