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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 large-state 64-bit generator suitable for {@code double} generation. This is slightly faster
22   * than the all-purpose generator {@link XoRoShiRo1024PlusPlus}.
23   *
24   * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 1024 bits
25   * and the period is 2<sup>1024</sup>-1.</p>
26   *
27   * @see <a href="http://xorshift.di.unimi.it/xoroshiro1024star.c">Original source code</a>
28   * @see <a href="http://xoshiro.di.unimi.it/">xorshiro / xoroshiro generators</a>
29   * @since 1.3
30   */
31  public class XoRoShiRo1024Star extends AbstractXoRoShiRo1024 {
32      /**
33       * Creates a new instance.
34       *
35       * @param seed Initial seed.
36       * If the length is larger than 16, only the first 16 elements will
37       * be used; if smaller, the remaining elements will be automatically
38       * set. A seed containing all zeros will create a non-functional generator.
39       */
40      public XoRoShiRo1024Star(long[] seed) {
41          super(seed);
42      }
43  
44      /**
45       * Creates a copy instance.
46       *
47       * @param source Source to copy.
48       */
49      protected XoRoShiRo1024Star(XoRoShiRo1024Star source) {
50          super(source);
51      }
52  
53      /** {@inheritDoc} */
54      @Override
55      protected long transform(long s0, long s15) {
56          return s0 * 0x9e3779b97f4a7c13L;
57      }
58  
59      /** {@inheritDoc} */
60      @Override
61      protected XoRoShiRo1024Star copy() {
62          // This exists to ensure the jump function returns
63          // the correct class type. It should not be public.
64          return new XoRoShiRo1024Star(this);
65      }
66  }