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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  package org.apache.commons.rng.simple.internal;
18  
19  import org.apache.commons.rng.core.source64.SplitMix64;
20  
21  /**
22   * Uses a {@code Long} value to seed a {@link SplitMix64} RNG and
23   * create a {@code long[]} with the requested number of random
24   * values.
25   *
26   * @since 1.0
27   */
28  public class Long2LongArray implements Seed2ArrayConverter<Long, long[]> {
29      /** Size of the output array. */
30      private final int size;
31  
32      /**
33       * @param size Size of the output array.
34       */
35      public Long2LongArray(int size) {
36          this.size = size;
37      }
38  
39  
40      /** {@inheritDoc} */
41      @Override
42      public long[] convert(Long seed) {
43          return convertSeed(seed, size);
44      }
45  
46      /**
47       * {@inheritDoc}
48       *
49       * @since 1.3
50       */
51      @Override
52      public long[] convert(Long seed, int outputSize) {
53          return convertSeed(seed, outputSize);
54      }
55  
56      /**
57       * Convert the seed.
58       *
59       * @param seed Input seed.
60       * @param size Output array size.
61       * @return the converted seed.
62       */
63      private static long[] convertSeed(Long seed, int size) {
64          final long[] out = new long[size];
65          final SplitMix64 rng = new SplitMix64(seed);
66          for (int i = 0; i < size; i++) {
67              out[i] = rng.nextLong();
68          }
69  
70          return out;
71      }
72  }