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 34 import java.math.BigInteger; 35 import jdk.test.lib.RandomFactory; 36 37 public 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 }