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 XoRoShiRo128StarStar}. 23 * 24 * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 128 bits 25 * and the period is 2<sup>128</sup>-1. Speed is expected to be similar to 26 * {@link XoShiRo256Plus}.</p> 27 * 28 * @see <a href="http://xoshiro.di.unimi.it/xoroshiro128plus.c">Original source code</a> 29 * @see <a href="http://xoshiro.di.unimi.it/">xorshiro / xoroshiro generators</a> 30 * @since 1.3 31 */ 32 public class XoRoShiRo128Plus extends AbstractXoRoShiRo128 { 33 /** 34 * Creates a new instance. 35 * 36 * @param seed Initial seed. 37 * If the length is larger than 2, only the first 2 elements will 38 * be used; if smaller, the remaining elements will be automatically 39 * set. A seed containing all zeros will create a non-functional generator. 40 */ 41 public XoRoShiRo128Plus(long[] seed) { 42 super(seed); 43 } 44 45 /** 46 * Creates a new instance using a 2 element seed. 47 * A seed containing all zeros will create a non-functional generator. 48 * 49 * @param seed0 Initial seed element 0. 50 * @param seed1 Initial seed element 1. 51 */ 52 public XoRoShiRo128Plus(long seed0, long seed1) { 53 super(seed0, seed1); 54 } 55 56 /** 57 * Creates a copy instance. 58 * 59 * @param source Source to copy. 60 */ 61 protected XoRoShiRo128Plus(XoRoShiRo128Plus source) { 62 super(source); 63 } 64 65 /** {@inheritDoc} */ 66 @Override 67 protected long nextOutput() { 68 return state0 + state1; 69 } 70 71 /** {@inheritDoc} */ 72 @Override 73 protected XoRoShiRo128Plus 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 XoRoShiRo128Plus(this); 77 } 78 }