| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| package org.apache.commons.rng.core.source32; |
| |
| /** |
| * A Permuted Congruential Generator (PCG) that is composed of a 64-bit Linear Congruential |
| * Generator (LCG) combined with the XSH-RR (xorshift; random rotate) output |
| * transformation to create 32-bit output. |
| * |
| * <p>State size is 128 bits and the period is 2<sup>64</sup>.</p> |
| * |
| * @see <a href="http://www.pcg-random.org/"> |
| * PCG, A Family of Better Random Number Generators</a> |
| * @since 1.3 |
| */ |
| public class PcgXshRr32 extends AbstractPcg6432 { |
| /** |
| * Creates a new instance using a default increment. |
| * |
| * @param seed Initial state. |
| * @since 1.4 |
| */ |
| public PcgXshRr32(Long seed) { |
| super(seed); |
| } |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param seed Initial seed. |
| * If the length is larger than 2, only the first 2 elements will |
| * be used; if smaller, the remaining elements will be automatically set. |
| * |
| * <p>The 1st element is used to set the LCG state. The 2nd element is used |
| * to set the LCG increment; the most significant bit |
| * is discarded by left shift and the increment is set to odd.</p> |
| */ |
| public PcgXshRr32(long[] seed) { |
| super(seed); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| protected int transform(long x) { |
| final int count = (int)(x >>> 59); |
| return Integer.rotateRight((int)((x ^ (x >>> 18)) >>> 27), count); |
| } |
| } |