1 /* 2 * Copyright (c) 2003, 2015, 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 /lib/testlibrary/ 27 * @build jdk.testlibrary.* 28 * @run main BitTwiddle 29 * @bug 4495754 8078672 30 * @summary Basic test for int bit twiddling (use -Dseed=X to set PRNG seed) 31 * @author Josh Bloch 32 * @key randomness 33 */ 34 35 import java.util.Random; 36 import static java.lang.Integer.*; 37 38 public class BitTwiddle { 39 private static final int N = 1000; // # of repetitions per test 40 41 public static void main(String args[]) { 42 Random rnd = RandomFactory.getRandom(); 43 44 if (highestOneBit(0) != 0) 45 throw new RuntimeException("a"); 46 if (highestOneBit(-1) != MIN_VALUE) 47 throw new RuntimeException("b"); 48 if (highestOneBit(1) != 1) 49 throw new RuntimeException("c"); 50 51 if (lowestOneBit(0) != 0) 52 throw new RuntimeException("d"); 53 if (lowestOneBit(-1) != 1) 54 throw new RuntimeException("e"); 55 if (lowestOneBit(MIN_VALUE) != MIN_VALUE) 56 throw new RuntimeException("f"); 57 58 for (int i = 0; i < N; i++) { 59 int x = rnd.nextInt(); 60 if (highestOneBit(x) != reverse(lowestOneBit(reverse(x)))) 61 throw new RuntimeException("g: " + toHexString(x)); 62 } 63 64 if (numberOfLeadingZeros(0) != SIZE) 65 throw new RuntimeException("h"); 66 if (numberOfLeadingZeros(-1) != 0) 67 throw new RuntimeException("i"); 68 if (numberOfLeadingZeros(1) != (SIZE - 1)) 69 throw new RuntimeException("j"); 70 71 if (numberOfTrailingZeros(0) != SIZE) 72 throw new RuntimeException("k"); 73 if (numberOfTrailingZeros(1) != 0) 74 throw new RuntimeException("l"); 75 if (numberOfTrailingZeros(MIN_VALUE) != (SIZE - 1)) 76 throw new RuntimeException("m"); 77 78 for (int i = 0; i < N; i++) { 79 int x = rnd.nextInt(); 80 if (numberOfLeadingZeros(x) != numberOfTrailingZeros(reverse(x))) 81 throw new RuntimeException("n: " + toHexString(x)); 82 } 83 84 if (bitCount(0) != 0) 85 throw new RuntimeException("o"); 86 87 for (int i = 0; i < SIZE; i++) { 88 int pow2 = 1 << i; 89 if (bitCount(pow2) != 1) 90 throw new RuntimeException("p: " + i); 91 if (bitCount(pow2 -1) != i) 92 throw new RuntimeException("q: " + i); 93 } 94 95 for (int i = 0; i < N; i++) { 96 int x = rnd.nextInt(); 97 if (bitCount(x) != bitCount(reverse(x))) 98 throw new RuntimeException("r: " + toHexString(x)); 99 } 100 101 for (int i = 0; i < N; i++) { 102 int x = rnd.nextInt(); 103 int dist = rnd.nextInt(); 104 if (bitCount(x) != bitCount(rotateRight(x, dist))) 105 throw new RuntimeException("s: " + toHexString(x) + 106 toHexString(dist)); 107 if (bitCount(x) != bitCount(rotateLeft(x, dist))) 108 throw new RuntimeException("t: " + toHexString(x) + 109 toHexString(dist)); 110 if (rotateRight(x, dist) != rotateLeft(x, -dist)) 111 throw new RuntimeException("u: " + toHexString(x) + 112 toHexString(dist)); 113 if (rotateRight(x, -dist) != rotateLeft(x, dist)) 114 throw new RuntimeException("v: " + toHexString(x) + 115 toHexString(dist)); 116 } 117 118 if (signum(0) != 0 || signum(1) != 1 || signum(-1) != -1 119 || signum(MIN_VALUE) != -1 || signum(MAX_VALUE) != 1) 120 throw new RuntimeException("w"); 121 122 for (int i = 0; i < N; i++) { 123 int x = rnd.nextInt(); 124 int sign = (x < 0 ? -1 : (x == 0 ? 0 : 1)); 125 if (signum(x) != sign) 126 throw new RuntimeException("x: " + toHexString(x)); 127 } 128 129 if(reverseBytes(0xaabbccdd) != 0xddccbbaa) 130 throw new RuntimeException("y"); 131 132 for (int i = 0; i < N; i++) { 133 int x = rnd.nextInt(); 134 if (bitCount(x) != bitCount(reverseBytes(x))) 135 throw new RuntimeException("z: " + toHexString(x)); 136 } 137 } 138 }