/*

 * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

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 */

package org.openjdk.bench.vm.compiler;

import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

import org.openjdk.jmh.annotations.Mode;

import org.openjdk.jmh.annotations.OutputTimeUnit;

import org.openjdk.jmh.annotations.Param;

import org.openjdk.jmh.annotations.Scope;

import org.openjdk.jmh.annotations.Setup;

import org.openjdk.jmh.annotations.State;

import java.util.concurrent.TimeUnit;

/**

 * Tests speed of multiplication calculations with constants.

 */

@BenchmarkMode(Mode.AverageTime)

@OutputTimeUnit(TimeUnit.NANOSECONDS)

@State(Scope.Thread)

public class Multiplication {

    @Param("500")

    private int arraySize;

    private long[] longArraySmall, longArrayBig;

    @Setup

    public void setupSubclass() {

        longArraySmall = new long[arraySize];

        longArrayBig = new long[arraySize];

        /*

         * small values always have higher 32 bits cleared. big values always

         * have higher 32 bits set.

         */

        for (int i = 0; i < arraySize; i++) {

            longArraySmall[i] = 100L * i + i;

            longArrayBig[i] = ((100L * i + i) << 32) + 4543 + i * 4;

        }

    }

    /* helper for small constant benchmarks. */

    private static long smallConstantHelper(long[] values) {

        long sum = 0;

        for (long value : values) {

            sum += value * 453543L;

        }

        return sum;

    }

    /* helper for big constant benchmarks. */

    private static long bigConstantHelper(long[] values) {

        long sum = 0;

        for (long value : values) {

            sum += value * 4554345533543L;

        }

        return sum;

    }

    /**

     * Test multiplications of longs. One of the operands is a small constant and the other is a variable that always is

     * small.

     */

    @Benchmark

    public long testLongSmallVariableSmallConstantMul() {

        return smallConstantHelper(longArraySmall);

    }

    /**

     * Test multiplications of longs. One of the operands is a big constant and the other is a variable that always is

     * small.

     */

    @Benchmark

    public long testLongSmallVariableBigConstantMul() {

        return bigConstantHelper(longArraySmall);

    }

    /**

     * Test multiplications of longs. One of the operands is a small constant and the other is a variable that always is

     * big.

     */

    @Benchmark

    public long testLongBigVariableSmallConstantMul() {

        return smallConstantHelper(longArrayBig);

    }

    /**

     * Test multiplications of longs. One of the operands is a big constant and the other is a variable that always is

     * big.

     */

    @Benchmark

    public long testLongBigVariableBigConstantMul() {

        return bigConstantHelper(longArrayBig);

    }

}