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Cleanup MersenneTwister

This commit is contained in:
Christoph Diehl 2017-04-06 15:49:58 +02:00
parent eda32a4f8e
commit 7c7ebd7e40
1 changed files with 49 additions and 77 deletions
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126
random/mersennetwister.js
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@ -1,64 +1,20 @@
// this program is a JavaScript version of Mersenne Twister, with concealment and encapsulation in class,
// an almost straight conversion from the original program, mt19937ar.c,
// translated by y. okada on July 17, 2006.
// Changes by Jesse Ruderman:
// * Use intish/int32 rather than uint32 for intermediate calculations
// (see https://bugzilla.mozilla.org/show_bug.cgi?id=883748#c1)
// * Added functions for exporting/importing the entire PRNG state
// * Removed parts not needed for fuzzing
// in this program, procedure descriptions and comments of original source code were not removed.
// lines commented with //c// were originally descriptions of c procedure. and a few following lines are appropriate JavaScript descriptions.
// lines commented with /* and */ are original comments.
// lines commented with // are additional comments in this JavaScript version.
// before using this version, create at least one instance of MersenneTwister19937 class, and initialize the each state, given below in c comments, of all the instances.
/* 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/. */
/*
A C-program for MT19937, with initialization improved 2002/1/26.
Coded by Takuji Nishimura and Makoto Matsumoto.
* JavaScript version of Mersenne Twister
*
* @author Yasuharu Okada
*
*/
Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The names of its contributors may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Any feedback is very welcome.
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
*/
function MersenneTwister19937()
function MersenneTwister()
{
const N = 624;
const M = 397;
const UPPER_MASK = 0x80000000;
const LOWER_MASK = 0x7fffffff;
const MAG01 = new Int32Array([0, 0x9908b0df]);
var mt = new Int32Array(N); /* the array for the state vector */
@ -66,38 +22,50 @@ function MersenneTwister19937()
this.seed = function (s) {
mt[0] = s | 0;
for (mti=1; mti<N; mti++) {
mt[mti] = Math.imul(1812433253, mt[mti-1] ^ (mt[mti-1] >>> 30)) + mti;
for (mti = 1; mti < N; mti++) {
mt[mti] = Math.imul(1812433253, mt[mti - 1] ^ (mt[mti - 1] >>> 30)) + mti;
}
};
this.export_state = function() { return [mt, mti]; };
this.import_state = function(s) { mt = s[0]; mti = s[1]; };
this.export_mta = function() { return mt; };
this.import_mta = function(_mta) { mt = _mta; };
this.export_mti = function() { return mti; };
this.import_mti = function(_mti) { mti = _mti; };
this.export_state = function() {
return [mt, mti];
};
function mag01(y)
{
return MAG01[y & 0x1];
}
this.import_state = function(s) {
mt = s[0];
mti = s[1];
};
this.export_mta = function() {
return mt;
};
this.import_mta = function(_mta) {
mt = _mta;
};
this.export_mti = function() {
return mti;
};
this.import_mti = function(_mti) {
mti = _mti;
};
this.int32 = function () {
var y;
var kk;
var y, kk;
if (mti >= N) { /* generate N words at one time */
for (kk=0;kk<N-M;kk++) {
y = ((mt[kk]&0x80000000)|(mt[kk+1]&0x7fffffff));
mt[kk] = (mt[kk+M] ^ (y >>> 1) ^ mag01(y));
for (kk = 0; kk < N-M; kk++) {
y = ((mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK));
mt[kk] = (mt[kk+M] ^ (y >>> 1) ^ MAG01[y & 0x1]);
}
for (;kk<N-1;kk++) {
y = ((mt[kk]&0x80000000)|(mt[kk+1]&0x7fffffff));
mt[kk] = (mt[kk+(M-N)] ^ (y >>> 1) ^ mag01(y));
for (; kk < N-1; kk++) {
y = ((mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK));
mt[kk] = (mt[kk+(M-N)] ^ (y >>> 1) ^ MAG01[y & 0x1]);
}
y = ((mt[N-1]&0x80000000)|(mt[0]&0x7fffffff));
mt[N-1] = (mt[M-1] ^ (y >>> 1) ^ mag01(y));
y = ((mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK));
mt[N-1] = (mt[M-1] ^ (y >>> 1) ^ MAG01[y & 0x1]);
mti = 0;
}
@ -111,4 +79,8 @@ function MersenneTwister19937()
return y;
};
this.genrand_real2 = function () {
return this.genrand_int32() * (1.0 / 4294967296.0);
}
}