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 large-state 64-bit generator suitable for {@code double} generation. This is slightly faster
022 * than the all-purpose generator {@link XoRoShiRo1024PlusPlus}.
023 *
024 * <p>This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 1024 bits
025 * and the period is 2<sup>1024</sup>-1.</p>
026 *
027 * @see <a href="http://xorshift.di.unimi.it/xoroshiro1024star.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 XoRoShiRo1024Star extends AbstractXoRoShiRo1024 {
032    /**
033     * Creates a new instance.
034     *
035     * @param seed Initial seed.
036     * If the length is larger than 16, only the first 16 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 XoRoShiRo1024Star(long[] seed) {
041        super(seed);
042    }
043
044    /**
045     * Creates a copy instance.
046     *
047     * @param source Source to copy.
048     */
049    protected XoRoShiRo1024Star(XoRoShiRo1024Star source) {
050        super(source);
051    }
052
053    /** {@inheritDoc} */
054    @Override
055    protected long transform(long s0, long s15) {
056        return s0 * 0x9e3779b97f4a7c13L;
057    }
058
059    /** {@inheritDoc} */
060    @Override
061    protected XoRoShiRo1024Star copy() {
062        // This exists to ensure the jump function returns
063        // the correct class type. It should not be public.
064        return new XoRoShiRo1024Star(this);
065    }
066}