1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.rng.core.source32;
18
19 /**
20 * A Permuted Congruential Generator (PCG) that is composed of a 64-bit Multiplicative Congruential
21 * Generator (MCG) combined with the XSH-RS (xorshift; random shift) output
22 * transformation to create 32-bit output.
23 *
24 * <p>State size is 64 bits and the period is 2<sup>62</sup>.</p>
25 *
26 * @see <a href="http://www.pcg-random.org/">
27 * PCG, A Family of Better Random Number Generators</a>
28 * @since 1.3
29 */
30 public class PcgMcgXshRs32 extends AbstractPcgMcg6432 {
31 /**
32 * Creates a new instance.
33 *
34 * @param seed Initial seed.
35 */
36 public PcgMcgXshRs32(Long seed) {
37 super(seed);
38 }
39
40 /** {@inheritDoc} */
41 @Override
42 protected int transform(long x) {
43 final int count = (int)(x >>> 61);
44 return (int)((x ^ (x >>> 22)) >>> (22 + count));
45 }
46 }