1/*
2 * Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24/*
25 * @test
26 * @library /test/lib
27 * @build jdk.test.lib.RandomFactory
28 * @run main MultiplicationTests
29 * @bug 5100935
30 * @summary Tests for multiplication methods (use -Dseed=X to set PRNG seed)
31 * @key randomness
32 */
33
34import java.math.BigInteger;
35import jdk.test.lib.RandomFactory;
36
37public class MultiplicationTests {
38    private MultiplicationTests(){}
39
40    // Number of random products to test.
41    private static final int COUNT = 1 << 16;
42
43    // Initialize shared random number generator
44    private static java.util.Random rnd = RandomFactory.getRandom();
45
46    // Calculate high 64 bits of 128 product using BigInteger.
47    private static long multiplyHighBigInt(long x, long y) {
48        return BigInteger.valueOf(x).multiply(BigInteger.valueOf(y))
49            .shiftRight(64).longValue();
50    }
51
52    // Check Math.multiplyHigh(x,y) against multiplyHighBigInt(x,y)
53    private static boolean check(long x, long y) {
54        long p1 = multiplyHighBigInt(x, y);
55        long p2 = Math.multiplyHigh(x, y);
56        if (p1 != p2) {
57            System.err.printf("Error - x:%d y:%d p1:%d p2:%d\n", x, y, p1, p2);
58            return false;
59        } else {
60            return true;
61        }
62    }
63
64    private static int testMultiplyHigh() {
65        int failures = 0;
66
67        // check some boundary cases
68        long[][] v = new long[][]{
69            {0L, 0L},
70            {-1L, 0L},
71            {0L, -1L},
72            {1L, 0L},
73            {0L, 1L},
74            {-1L, -1L},
75            {-1L, 1L},
76            {1L, -1L},
77            {1L, 1L},
78            {Long.MAX_VALUE, Long.MAX_VALUE},
79            {Long.MAX_VALUE, -Long.MAX_VALUE},
80            {-Long.MAX_VALUE, Long.MAX_VALUE},
81            {Long.MAX_VALUE, Long.MIN_VALUE},
82            {Long.MIN_VALUE, Long.MAX_VALUE},
83            {Long.MIN_VALUE, Long.MIN_VALUE}
84        };
85
86        for (long[] xy : v) {
87            if(!check(xy[0], xy[1])) {
88                failures++;
89            }
90        }
91
92        // check some random values
93        for (int i = 0; i < COUNT; i++) {
94            if (!check(rnd.nextLong(), rnd.nextLong())) {
95                failures++;
96            }
97        }
98
99        return failures;
100    }
101
102    public static void main(String argv[]) {
103        int failures = testMultiplyHigh();
104
105        if (failures > 0) {
106            System.err.println("Multiplication testing encountered "
107                               + failures + " failures.");
108            throw new RuntimeException();
109        } else {
110            System.out.println("MultiplicationTests succeeded");
111        }
112    }
113}
114