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 import org.apache.commons.rng.core.util.NumberFactory; 21 22 /** 23 * A fast RNG, with 64 bits of state, that can be used to initialize the 24 * state of other generators. 25 * 26 * @see <a href="http://xorshift.di.unimi.it/splitmix64.c"> 27 * Original source code</a> 28 * 29 * @since 1.0 30 */ 31 public class SplitMix64 extends LongProvider { 32 /** State. */ 33 private long state; 34 35 /** 36 * Creates a new instance. 37 * 38 * @param seed Initial seed. 39 * @since 1.3 40 */ 41 public SplitMix64(long seed) { 42 state = seed; 43 } 44 45 /** 46 * Creates a new instance. 47 * 48 * @param seed Initial seed. 49 */ 50 public SplitMix64(Long seed) { 51 // Support for Long to allow instantiation through the 52 // rng.simple.RandomSource factory methods. 53 setSeedInternal(seed); 54 } 55 56 /** 57 * Seeds the RNG. 58 * 59 * @param seed Seed. 60 */ 61 private void setSeedInternal(Long seed) { 62 state = seed.longValue(); 63 } 64 65 /** {@inheritDoc} */ 66 @Override 67 public long next() { 68 long z = state += 0x9e3779b97f4a7c15L; 69 z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; 70 z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL; 71 return z ^ (z >>> 31); 72 } 73 74 /** {@inheritDoc} */ 75 @Override 76 protected byte[] getStateInternal() { 77 return composeStateInternal(NumberFactory.makeByteArray(state), 78 super.getStateInternal()); 79 } 80 81 /** {@inheritDoc} */ 82 @Override 83 protected void setStateInternal(byte[] s) { 84 final byte[][] c = splitStateInternal(s, 8); 85 86 state = NumberFactory.makeLong(c[0]); 87 super.setStateInternal(c[1]); 88 } 89 }