001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 018package org.apache.commons.rng.core.source64; 019 020/** 021 * A fast all-purpose 64-bit generator. 022 * 023 * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 128 bits 024 * and the period is 2<sup>128</sup>-1. Speed is expected to be similar to 025 * {@link XoShiRo256StarStar}.</p> 026 * 027 * @see <a href="http://xoshiro.di.unimi.it/xoroshiro128starstar.c">Original source code</a> 028 * @see <a href="http://xoshiro.di.unimi.it/">xorshiro / xoroshiro generators</a> 029 * @since 1.3 030 */ 031public class XoRoShiRo128StarStar extends AbstractXoRoShiRo128 { 032 /** 033 * Creates a new instance. 034 * 035 * @param seed Initial seed. 036 * If the length is larger than 2, only the first 2 elements will 037 * be used; if smaller, the remaining elements will be automatically 038 * set. A seed containing all zeros will create a non-functional generator. 039 */ 040 public XoRoShiRo128StarStar(long[] seed) { 041 super(seed); 042 } 043 044 /** 045 * Creates a new instance using a 2 element seed. 046 * A seed containing all zeros will create a non-functional generator. 047 * 048 * @param seed0 Initial seed element 0. 049 * @param seed1 Initial seed element 1. 050 */ 051 public XoRoShiRo128StarStar(long seed0, long seed1) { 052 super(seed0, seed1); 053 } 054 055 /** 056 * Creates a copy instance. 057 * 058 * @param source Source to copy. 059 */ 060 protected XoRoShiRo128StarStar(XoRoShiRo128StarStar source) { 061 super(source); 062 } 063 064 /** {@inheritDoc} */ 065 @Override 066 protected long nextOutput() { 067 return Long.rotateLeft(state0 * 5, 7) * 9; 068 } 069 070 /** {@inheritDoc} */ 071 @Override 072 protected XoRoShiRo128StarStar copy() { 073 // This exists to ensure the jump function performed in the super class returns 074 // the correct class type. It should not be public. 075 return new XoRoShiRo128StarStar(this); 076 } 077}