1 /* 2 * Copyright (c) 2003, 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 * @run main BitTwiddle 28 * @bug 4495754 8078672 29 * @summary Basic test for long bit twiddling (use -Dseed=X to set PRNG seed) 30 * @author Josh Bloch 31 * @key randomness 32 */ 33 34 import java.util.Random; 35 import jdk.test.lib.RandomFactory; 36 import static java.lang.Long.*; 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 long x = rnd.nextLong(); 60 61 String expected = new StringBuilder() 62 .append(leftpad(toBinaryString(x), 64)) 63 .reverse().toString(); 64 65 String actual = leftpad(toBinaryString(reverse(x)), 64); 66 67 if (!expected.equals(actual)) { 68 throw new RuntimeException("reverse: \n" + 69 expected + " \n" + actual); 70 } 71 } 72 73 for (int i = 0; i < N; i++) { 74 long x = rnd.nextLong(); 75 if (highestOneBit(x) != reverse(lowestOneBit(reverse(x)))) 76 throw new RuntimeException("g: " + toHexString(x)); 77 } 78 79 if (numberOfLeadingZeros(0) != SIZE) 80 throw new RuntimeException("h"); 81 if (numberOfLeadingZeros(-1) != 0) 82 throw new RuntimeException("i"); 83 if (numberOfLeadingZeros(1) != (SIZE - 1)) 84 throw new RuntimeException("j"); 85 86 if (numberOfTrailingZeros(0) != SIZE) 87 throw new RuntimeException("k"); 88 if (numberOfTrailingZeros(1) != 0) 89 throw new RuntimeException("l"); 90 if (numberOfTrailingZeros(MIN_VALUE) != (SIZE - 1)) 91 throw new RuntimeException("m"); 92 93 for (int i = 0; i < N; i++) { 94 long x = rnd.nextLong(); 95 if (numberOfLeadingZeros(x) != numberOfTrailingZeros(reverse(x))) 96 throw new RuntimeException("n: " + toHexString(x)); 97 } 98 99 if (bitCount(0) != 0) 100 throw new RuntimeException("o"); 101 102 for (int i = 0; i < SIZE; i++) { 103 long pow2 = 1L << i; 104 if (bitCount(pow2) != 1) 105 throw new RuntimeException("p: " + i); 106 if (bitCount(pow2 -1) != i) 107 throw new RuntimeException("q: " + i); 108 } 109 110 for (int i = 0; i < N; i++) { 111 long x = rnd.nextLong(); 112 if (bitCount(x) != bitCount(reverse(x))) 113 throw new RuntimeException("r: " + toHexString(x)); 114 } 115 116 for (int i = 0; i < N; i++) { 117 long x = rnd.nextLong(); 118 int dist = rnd.nextInt(); 119 if (bitCount(x) != bitCount(rotateRight(x, dist))) 120 throw new RuntimeException("s: " + toHexString(x) + 121 toHexString(dist)); 122 if (bitCount(x) != bitCount(rotateLeft(x, dist))) 123 throw new RuntimeException("t: " + toHexString(x) + 124 toHexString(dist)); 125 if (rotateRight(x, dist) != rotateLeft(x, -dist)) 126 throw new RuntimeException("u: " + toHexString(x) + 127 toHexString(dist)); 128 if (rotateRight(x, -dist) != rotateLeft(x, dist)) 129 throw new RuntimeException("v: " + toHexString(x) + 130 toHexString(dist)); 131 } 132 133 if (signum(0) != 0 || signum(1) != 1 || signum(-1) != -1 134 || signum(MIN_VALUE) != -1 || signum(MAX_VALUE) != 1) 135 throw new RuntimeException("w"); 136 137 for (int i = 0; i < N; i++) { 138 long x = rnd.nextLong(); 139 int sign = (x < 0 ? -1 : (x == 0 ? 0 : 1)); 140 if (signum(x) != sign) 141 throw new RuntimeException("x: " + toHexString(x)); 142 } 143 144 if(reverseBytes(0xaabbccdd11223344L) != 0x44332211ddccbbaaL) 145 throw new RuntimeException("y"); 146 147 for (int i = 0; i < N; i++) { 148 long x = rnd.nextLong(); 149 if (bitCount(x) != bitCount(reverseBytes(x))) 150 throw new RuntimeException("z: " + toHexString(x)); 151 } 152 } 153 154 private static String leftpad(String s, int width) { 155 String r = s; 156 for (int c = 0; c < width - s.length(); c++) { 157 r = "0" + r; 158 } 159 return r; 160 } 161 }