Random64.java
/*
* Java Genetic Algorithm Library (@__identifier__@).
* Copyright (c) @__year__@ Franz Wilhelmstötter
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Author:
* Franz Wilhelmstötter (franz.wilhelmstoetter@gmx.at)
*/
package org.jenetics.util;
import static java.lang.Math.min;
import java.util.Random;
import org.jenetics.internal.math.random;
/**
* An abstract base class which eases the implementation of {@code Random}
* objects which natively creates random {@code long} values. All other
* {@code Random} functions are optimized using this {@code long} values.
*
* [code]
* public class MyRandom64 extends Random64 {
* \@Override
* public long nextLong() {
* // Only this method must be implemented.
* ...
* }
* }
* [/code]
*
* @author <a href="mailto:franz.wilhelmstoetter@gmx.at">Franz Wilhelmstötter</a>
* @since 1.3
* @version 1.3 — <em>$Date: 2014-02-15 $</em>
*/
public abstract class Random64 extends PRNG {
private static final long serialVersionUID = 1L;
private static final int LONG_BYTE_SIZE = 8;
protected Random64(long seed) {
super(seed);
}
protected Random64() {
this(math.random.seed());
}
/**
* Force to explicitly override the Random.nextLong() method. All other
* methods of this class are implemented by calling this method.
*/
@Override
public abstract long nextLong();
@Override
public boolean nextBoolean() {
return (nextLong() & 0x8000000000000000L) != 0L;
}
@Override
public int nextInt() {
return (int)(nextLong() >>> Integer.SIZE);
}
@Override
protected int next(final int bits) {
return (int)(nextLong() >>> (Long.SIZE - bits));
}
/**
* Optimized version of the {@link Random#nextBytes(byte[])} method for
* 64-bit random engines.
*/
@Override
public void nextBytes(final byte[] bytes) {
for (int i = 0, len = bytes.length; i < len;) {
int n = min(len - i, LONG_BYTE_SIZE);
for (long x = nextLong(); --n >= 0; x >>= Byte.SIZE) {
bytes[i++] = (byte)x;
}
}
}
@Override
public float nextFloat() {
return random.toFloat2(nextLong());
}
/**
* Optimized version of the {@link Random#nextDouble()} method for 64-bit
* random engines.
*/
@Override
public double nextDouble() {
return random.toDouble2(nextLong());
}
}