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 64-bit generator suitable for {@code double} generation. This is slightly faster than the 022 * all-purpose generator {@link XoShiRo256StarStar}. 023 * 024 * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 256 bits 025 * and the period is 2<sup>256</sup>-1.</p> 026 * 027 * @see <a href="http://xoshiro.di.unimi.it/xoshiro256plus.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 XoShiRo256Plus extends AbstractXoShiRo256 { 032 /** 033 * Creates a new instance. 034 * 035 * @param seed Initial seed. 036 * If the length is larger than 4, only the first 4 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 XoShiRo256Plus(long[] seed) { 041 super(seed); 042 } 043 044 /** 045 * Creates a new instance using a 4 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 * @param seed2 Initial seed element 2. 051 * @param seed3 Initial seed element 3. 052 */ 053 public XoShiRo256Plus(long seed0, long seed1, long seed2, long seed3) { 054 super(seed0, seed1, seed2, seed3); 055 } 056 057 /** 058 * Creates a copy instance. 059 * 060 * @param source Source to copy. 061 */ 062 protected XoShiRo256Plus(XoShiRo256Plus source) { 063 super(source); 064 } 065 066 /** {@inheritDoc} */ 067 @Override 068 protected long nextOutput() { 069 return state0 + state3; 070 } 071 072 /** {@inheritDoc} */ 073 @Override 074 protected XoShiRo256Plus copy() { 075 // This exists to ensure the jump function performed in the super class returns 076 // the correct class type. It should not be public. 077 return new XoShiRo256Plus(this); 078 } 079}