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 */
017package org.apache.commons.rng.simple.internal;
018
019import org.apache.commons.rng.core.source64.SplitMix64;
020
021/**
022 * Uses a {@code Long} value to seed a {@link SplitMix64} RNG and
023 * create a {@code long[]} with the requested number of random
024 * values.
025 *
026 * @since 1.0
027 */
028public class Long2LongArray implements Seed2ArrayConverter<Long, long[]> {
029    /** Size of the output array. */
030    private final int size;
031
032    /**
033     * @param size Size of the output array.
034     */
035    public Long2LongArray(int size) {
036        this.size = size;
037    }
038
039
040    /** {@inheritDoc} */
041    @Override
042    public long[] convert(Long seed) {
043        return convertSeed(seed, size);
044    }
045
046    /**
047     * {@inheritDoc}
048     *
049     * @since 1.3
050     */
051    @Override
052    public long[] convert(Long seed, int outputSize) {
053        return convertSeed(seed, outputSize);
054    }
055
056    /**
057     * Convert the seed.
058     *
059     * @param seed Input seed.
060     * @param size Output array size.
061     * @return the converted seed.
062     */
063    private static long[] convertSeed(Long seed, int size) {
064        final long[] out = new long[size];
065        final SplitMix64 rng = new SplitMix64(seed);
066        for (int i = 0; i < size; i++) {
067            out[i] = rng.nextLong();
068        }
069
070        return out;
071    }
072}