1 /* 2 * Copyright (c) 2003, 2018, 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 BitTwiddle 29 * @bug 4495754 8078672 30 * @summary Basic test for long 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 jdk.test.lib.RandomFactory; 37 import static java.lang.Long.*; 38 39 public class BitTwiddle { 40 private static final int N = 1000; // # of repetitions per test 41 main(String args[])42 public static void main(String args[]) { 43 Random rnd = RandomFactory.getRandom(); 44 45 if (highestOneBit(0) != 0) 46 throw new RuntimeException("a"); 47 if (highestOneBit(-1) != MIN_VALUE) 48 throw new RuntimeException("b"); 49 if (highestOneBit(1) != 1) 50 throw new RuntimeException("c"); 51 52 if (lowestOneBit(0) != 0) 53 throw new RuntimeException("d"); 54 if (lowestOneBit(-1) != 1) 55 throw new RuntimeException("e"); 56 if (lowestOneBit(MIN_VALUE) != MIN_VALUE) 57 throw new RuntimeException("f"); 58 59 for (int i = 0; i < N; i++) { 60 long x = rnd.nextLong(); 61 62 String expected = new StringBuilder() 63 .append(leftpad(toBinaryString(x), 64)) 64 .reverse().toString(); 65 66 String actual = leftpad(toBinaryString(reverse(x)), 64); 67 68 if (!expected.equals(actual)) { 69 throw new RuntimeException("reverse: \n" + 70 expected + " \n" + actual); 71 } 72 } 73 74 for (int i = 0; i < N; i++) { 75 long x = rnd.nextLong(); 76 if (highestOneBit(x) != reverse(lowestOneBit(reverse(x)))) 77 throw new RuntimeException("g: " + toHexString(x)); 78 } 79 80 if (numberOfLeadingZeros(0) != SIZE) 81 throw new RuntimeException("h"); 82 if (numberOfLeadingZeros(-1) != 0) 83 throw new RuntimeException("i"); 84 if (numberOfLeadingZeros(1) != (SIZE - 1)) 85 throw new RuntimeException("j"); 86 if (numberOfLeadingZeros(Long.MAX_VALUE) != 1) 87 throw new RuntimeException("lzmax"); 88 if (numberOfLeadingZeros(Integer.MAX_VALUE + 1L) != (SIZE - 32)) 89 throw new RuntimeException("lz32"); 90 91 if (numberOfTrailingZeros(0) != SIZE) 92 throw new RuntimeException("k"); 93 if (numberOfTrailingZeros(1) != 0) 94 throw new RuntimeException("l"); 95 if (numberOfTrailingZeros(MIN_VALUE) != (SIZE - 1)) 96 throw new RuntimeException("m"); 97 98 for (int i = 0; i < N; i++) { 99 long x = rnd.nextLong(); 100 if (numberOfLeadingZeros(x) != numberOfTrailingZeros(reverse(x))) 101 throw new RuntimeException("n: " + toHexString(x)); 102 } 103 for (long i = 1, r = SIZE - 1; i != 0; i <<= 1, r--) { 104 if (numberOfLeadingZeros(i) != (int)r || 105 numberOfTrailingZeros(i) != (SIZE - (int)r - 1) || 106 numberOfLeadingZeros(i) != numberOfTrailingZeros(reverse(i))) { 107 throw new RuntimeException("lzx: " + toHexString(i)); 108 } 109 } 110 111 if (bitCount(0) != 0) 112 throw new RuntimeException("o"); 113 114 for (int i = 0; i < SIZE; i++) { 115 long pow2 = 1L << i; 116 if (bitCount(pow2) != 1) 117 throw new RuntimeException("p: " + i); 118 if (bitCount(pow2 -1) != i) 119 throw new RuntimeException("q: " + i); 120 } 121 122 for (int i = 0; i < N; i++) { 123 long x = rnd.nextLong(); 124 if (bitCount(x) != bitCount(reverse(x))) 125 throw new RuntimeException("r: " + toHexString(x)); 126 } 127 128 for (int i = 0; i < N; i++) { 129 long x = rnd.nextLong(); 130 int dist = rnd.nextInt(); 131 if (bitCount(x) != bitCount(rotateRight(x, dist))) 132 throw new RuntimeException("s: " + toHexString(x) + 133 toHexString(dist)); 134 if (bitCount(x) != bitCount(rotateLeft(x, dist))) 135 throw new RuntimeException("t: " + toHexString(x) + 136 toHexString(dist)); 137 if (rotateRight(x, dist) != rotateLeft(x, -dist)) 138 throw new RuntimeException("u: " + toHexString(x) + 139 toHexString(dist)); 140 if (rotateRight(x, -dist) != rotateLeft(x, dist)) 141 throw new RuntimeException("v: " + toHexString(x) + 142 toHexString(dist)); 143 } 144 145 if (signum(0) != 0 || signum(1) != 1 || signum(-1) != -1 146 || signum(MIN_VALUE) != -1 || signum(MAX_VALUE) != 1) 147 throw new RuntimeException("w"); 148 149 for (int i = 0; i < N; i++) { 150 long x = rnd.nextLong(); 151 int sign = (x < 0 ? -1 : (x == 0 ? 0 : 1)); 152 if (signum(x) != sign) 153 throw new RuntimeException("x: " + toHexString(x)); 154 } 155 156 if(reverseBytes(0xaabbccdd11223344L) != 0x44332211ddccbbaaL) 157 throw new RuntimeException("y"); 158 159 for (int i = 0; i < N; i++) { 160 long x = rnd.nextLong(); 161 if (bitCount(x) != bitCount(reverseBytes(x))) 162 throw new RuntimeException("z: " + toHexString(x)); 163 } 164 } 165 166 private static final String ZEROS = "0".repeat(64); leftpad(String s, int width)167 private static String leftpad(String s, int width) { 168 return ZEROS.substring(0, width - s.length()) + s; 169 } 170 } 171