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 020import org.apache.commons.rng.core.util.NumberFactory; 021 022/** 023 * A fast RNG, with 64 bits of state, that can be used to initialize the 024 * state of other generators. 025 * 026 * @see <a href="http://xorshift.di.unimi.it/splitmix64.c"> 027 * Original source code</a> 028 * 029 * @since 1.0 030 */ 031public class SplitMix64 extends LongProvider { 032 /** State. */ 033 private long state; 034 035 /** 036 * Creates a new instance. 037 * 038 * @param seed Initial seed. 039 * @since 1.3 040 */ 041 public SplitMix64(long seed) { 042 state = seed; 043 } 044 045 /** 046 * Creates a new instance. 047 * 048 * @param seed Initial seed. 049 */ 050 public SplitMix64(Long seed) { 051 // Support for Long to allow instantiation through the 052 // rng.simple.RandomSource factory methods. 053 setSeedInternal(seed); 054 } 055 056 /** 057 * Seeds the RNG. 058 * 059 * @param seed Seed. 060 */ 061 private void setSeedInternal(Long seed) { 062 state = seed.longValue(); 063 } 064 065 /** {@inheritDoc} */ 066 @Override 067 public long next() { 068 long z = state += 0x9e3779b97f4a7c15L; 069 z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; 070 z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL; 071 return z ^ (z >>> 31); 072 } 073 074 /** {@inheritDoc} */ 075 @Override 076 protected byte[] getStateInternal() { 077 return composeStateInternal(NumberFactory.makeByteArray(state), 078 super.getStateInternal()); 079 } 080 081 /** {@inheritDoc} */ 082 @Override 083 protected void setStateInternal(byte[] s) { 084 final byte[][] c = splitStateInternal(s, 8); 085 086 state = NumberFactory.makeLong(c[0]); 087 super.setStateInternal(c[1]); 088 } 089}