/* * MersenneTwister.java * * Created on January 16, 2003, 4:53 PM * *  * Copyright (C) 2003 - Edwin S. Peer * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA  *   * This code is based on the implementation in GSL (GNU Scientific Library)  * which is also covered by the GNU General Public License. The original C  * source code is Copyright (C) 1998 Brian Gough. *  */package net.sourceforge.cilib.Random;import java.util.*;/** * * @author  espeer */public class MersenneTwister extends Random {        public MersenneTwister() {        super();    }        public MersenneTwister(long seed) {        super(seed);    }        public void setSeed (long seed) {        data = new long[N];                if (seed == 0) {            seed = 4357;        }        data[0] = seed & 0xffffffffL;        for (index = 1; index < N; ++index) {            data[index] = (1812433253L * (data[index - 1] ^ (data[index - 1] >>> 30)) + index);            data[index] &= 0xffffffffL;        }    }    protected int next(int bits) {        if (index >= N) {            int i;            for (i = 0; i < N - M; ++i) {                long y = (data[i] & UPPER_MASK) | (data[i + 1] & LOWER_MASK);                data[i] = data[i + M] ^ (y >>> 1);                if ((y & 1L) == 1L) {                    data[i] ^= 0x9908b0dfL;                }            }            for (; i < N - 1; ++i) {                long y = (data[i] & UPPER_MASK) | (data[i + 1] & LOWER_MASK);                data[i] = data[i + (M - N)] ^ (y >>> 1);                if ((y & 1L) == 1L) {                    data[i] ^= 0x9908b0dfL;                }            }            long y = (data[N - 1] & UPPER_MASK) | (data[0] & LOWER_MASK);            data[N - 1] = data[M - 1] ^ (y >>> 1);            if ((y & 1L) == 1L) {                data[N - 1] ^= 0x9908b0dfL;            }            index = 0;        }                long k = data[index];        k ^= (k >>> 11);        k ^= (k << 7) & 0x9d2c5680L;        k ^= (k << 15) & 0xefc60000L;        k ^= (k >>> 18);                ++index;                return (int) ((k & 0xffffffffL) >>> (32 - bits));    }        private long[] data;    private int index;        private static final int N = 624;    private static final int M = 397;    private static final long UPPER_MASK = 0x80000000L;    private static final long LOWER_MASK = 0x7fffffffL;}