XoShiRo256StarStar.java

  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.source64;

  18. /**
  19.  * A fast all-purpose 64-bit generator.
  20.  *
  21.  * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 256 bits
  22.  * and the period is 2<sup>256</sup>-1.</p>
  23.  *
  24.  * @see <a href="http://xoshiro.di.unimi.it/xoshiro256starstar.c">Original source code</a>
  25.  * @see <a href="http://xoshiro.di.unimi.it/">xorshiro / xoroshiro generators</a>
  26.  * @since 1.3
  27.  */
  28. public class XoShiRo256StarStar extends AbstractXoShiRo256 {
  29.     /**
  30.      * Creates a new instance.
  31.      *
  32.      * @param seed Initial seed.
  33.      * If the length is larger than 4, only the first 4 elements will
  34.      * be used; if smaller, the remaining elements will be automatically
  35.      * set. A seed containing all zeros will create a non-functional generator.
  36.      */
  37.     public XoShiRo256StarStar(long[] seed) {
  38.         super(seed);
  39.     }

  40.     /**
  41.      * Creates a new instance using a 4 element seed.
  42.      * A seed containing all zeros will create a non-functional generator.
  43.      *
  44.      * @param seed0 Initial seed element 0.
  45.      * @param seed1 Initial seed element 1.
  46.      * @param seed2 Initial seed element 2.
  47.      * @param seed3 Initial seed element 3.
  48.      */
  49.     public XoShiRo256StarStar(long seed0, long seed1, long seed2, long seed3) {
  50.         super(seed0, seed1, seed2, seed3);
  51.     }

  52.     /**
  53.      * Creates a copy instance.
  54.      *
  55.      * @param source Source to copy.
  56.      */
  57.     protected XoShiRo256StarStar(XoShiRo256StarStar source) {
  58.         super(source);
  59.     }

  60.     /** {@inheritDoc} */
  61.     @Override
  62.     protected long nextOutput() {
  63.         return Long.rotateLeft(state1 * 5, 7) * 9;
  64.     }

  65.     /** {@inheritDoc} */
  66.     @Override
  67.     protected XoShiRo256StarStar copy() {
  68.         // This exists to ensure the jump function performed in the super class returns
  69.         // the correct class type. It should not be public.
  70.         return new XoShiRo256StarStar(this);
  71.     }
  72. }