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
18 package org.apache.commons.rng.core.source64;
19
20 /**
21 * A fast all-purpose 64-bit generator.
22 *
23 * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 256 bits
24 * and the period is 2<sup>256</sup>-1.</p>
25 *
26 * @see <a href="http://xoshiro.di.unimi.it/xoshiro256starstar.c">Original source code</a>
27 * @see <a href="http://xoshiro.di.unimi.it/">xorshiro / xoroshiro generators</a>
28 * @since 1.3
29 */
30 public class XoShiRo256StarStar extends AbstractXoShiRo256 {
31 /**
32 * Creates a new instance.
33 *
34 * @param seed Initial seed.
35 * If the length is larger than 4, only the first 4 elements will
36 * be used; if smaller, the remaining elements will be automatically
37 * set. A seed containing all zeros will create a non-functional generator.
38 */
39 public XoShiRo256StarStar(long[] seed) {
40 super(seed);
41 }
42
43 /**
44 * Creates a new instance using a 4 element seed.
45 * A seed containing all zeros will create a non-functional generator.
46 *
47 * @param seed0 Initial seed element 0.
48 * @param seed1 Initial seed element 1.
49 * @param seed2 Initial seed element 2.
50 * @param seed3 Initial seed element 3.
51 */
52 public XoShiRo256StarStar(long seed0, long seed1, long seed2, long seed3) {
53 super(seed0, seed1, seed2, seed3);
54 }
55
56 /**
57 * Creates a copy instance.
58 *
59 * @param source Source to copy.
60 */
61 protected XoShiRo256StarStar(XoShiRo256StarStar source) {
62 super(source);
63 }
64
65 /** {@inheritDoc} */
66 @Override
67 protected long nextOutput() {
68 return Long.rotateLeft(state1 * 5, 7) * 9;
69 }
70
71 /** {@inheritDoc} */
72 @Override
73 protected XoShiRo256StarStar copy() {
74 // This exists to ensure the jump function performed in the super class returns
75 // the correct class type. It should not be public.
76 return new XoShiRo256StarStar(this);
77 }
78 }