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RanduRNG.java
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RanduRNG.java
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/*
* Copyright (c) 2014, 2015, Nuno Fachada
* 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.
*
* 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.
*/
package org.laseeb.pphpc;
import java.util.Random;
import java.util.concurrent.locks.ReentrantLock;
import org.uncommons.maths.binary.BinaryUtils;
import org.uncommons.maths.random.DefaultSeedGenerator;
import org.uncommons.maths.random.RepeatableRNG;
import org.uncommons.maths.random.SeedException;
import org.uncommons.maths.random.SeedGenerator;
/**
* Implementation of the RANDU random number generator. It is a poor quality
* generator used to test if it the PPHPC simulation works with poor generators.
*
* @author Nuno Fachada
*/
public class RanduRNG extends Random implements RepeatableRNG {
/* Generated serial version UID. */
private static final long serialVersionUID = -8761384561773317806L;
/* Seed size for RANDU. */
private static final int SEED_SIZE_BYTES = 4;
/* The poor constant for RANDU. */
private final int a = 65539;
/* RNG seed. */
private byte[] seed;
/* The RNG state. */
private int state;
/* Lock to prevent concurrent modification of the RNG's internal state. */
private final ReentrantLock lock = new ReentrantLock();
/**
* Creates a new RANDU RNG and seeds it using the default seeding strategy.
*/
public RanduRNG() {
this(DefaultSeedGenerator.getInstance().generateSeed(SEED_SIZE_BYTES));
}
/**
* Seed the RANDU RNG using the provided seed generation strategy.
*
* @param seedGenerator The seed generation strategy that will provide
* the seed value for this RNG.
* @throws SeedException If there is a problem generating a seed.
*/
public RanduRNG(SeedGenerator seedGenerator) throws SeedException {
this(seedGenerator.generateSeed(SEED_SIZE_BYTES));
}
/**
* Creates an RNG and seeds it with the specified seed data.
*
* @param seed The seed data used to initialize the RNG.
*/
public RanduRNG(byte[] seed) {
if (seed == null || seed.length != SEED_SIZE_BYTES) {
throw new IllegalArgumentException("RANDU RNG requires 32 bits of seed data.");
}
this.seed = seed.clone();
int[] state = BinaryUtils.convertBytesToInts(seed);
this.state = state[0];
}
/**
* @see org.uncommons.maths.random.RepeatableRNG#getSeed()
*/
public byte[] getSeed() {
return seed.clone();
}
/**
* @see java.util.Random#next(int bits)
*/
@Override
protected int next(int bits) {
try {
lock.lock();
this.state = this.a * this.state;
return this.state >>> (32 - bits);
} finally {
lock.unlock();
}
}
}