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 64-bit generator suitable for {@code double} generation. This is slightly faster than the 22 * all-purpose generator {@link XoShiRo256StarStar}. 23 * 24 * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 256 bits 25 * and the period is 2<sup>256</sup>-1.</p> 26 * 27 * @see <a href="http://xoshiro.di.unimi.it/xoshiro256plus.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 XoShiRo256Plus extends AbstractXoShiRo256 { 32 /** 33 * Creates a new instance. 34 * 35 * @param seed Initial seed. 36 * If the length is larger than 4, only the first 4 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 XoShiRo256Plus(long[] seed) { 41 super(seed); 42 } 43 44 /** 45 * Creates a new instance using a 4 element seed. 46 * A seed containing all zeros will create a non-functional generator. 47 * 48 * @param seed0 Initial seed element 0. 49 * @param seed1 Initial seed element 1. 50 * @param seed2 Initial seed element 2. 51 * @param seed3 Initial seed element 3. 52 */ 53 public XoShiRo256Plus(long seed0, long seed1, long seed2, long seed3) { 54 super(seed0, seed1, seed2, seed3); 55 } 56 57 /** 58 * Creates a copy instance. 59 * 60 * @param source Source to copy. 61 */ 62 protected XoShiRo256Plus(XoShiRo256Plus source) { 63 super(source); 64 } 65 66 /** {@inheritDoc} */ 67 @Override 68 protected long nextOutput() { 69 return state0 + state3; 70 } 71 72 /** {@inheritDoc} */ 73 @Override 74 protected XoShiRo256Plus copy() { 75 // This exists to ensure the jump function performed in the super class returns 76 // the correct class type. It should not be public. 77 return new XoShiRo256Plus(this); 78 } 79 }