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 all-purpose 64-bit generator. 22 * 23 * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 128 bits 24 * and the period is 2<sup>128</sup>-1. Speed is expected to be similar to 25 * {@link XoShiRo256StarStar}.</p> 26 * 27 * @see <a href="http://xoshiro.di.unimi.it/xoroshiro128starstar.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 XoRoShiRo128StarStar extends AbstractXoRoShiRo128 { 32 /** 33 * Creates a new instance. 34 * 35 * @param seed Initial seed. 36 * If the length is larger than 2, only the first 2 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 XoRoShiRo128StarStar(long[] seed) { 41 super(seed); 42 } 43 44 /** 45 * Creates a new instance using a 2 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 */ 51 public XoRoShiRo128StarStar(long seed0, long seed1) { 52 super(seed0, seed1); 53 } 54 55 /** 56 * Creates a copy instance. 57 * 58 * @param source Source to copy. 59 */ 60 protected XoRoShiRo128StarStar(XoRoShiRo128StarStar source) { 61 super(source); 62 } 63 64 /** {@inheritDoc} */ 65 @Override 66 protected long nextOutput() { 67 return Long.rotateLeft(state0 * 5, 7) * 9; 68 } 69 70 /** {@inheritDoc} */ 71 @Override 72 protected XoRoShiRo128StarStar copy() { 73 // This exists to ensure the jump function performed in the super class returns 74 // the correct class type. It should not be public. 75 return new XoRoShiRo128StarStar(this); 76 } 77 }