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 package test.java.lang.Long; 36 37 import java.util.Random; 38 import jdk.test.lib.RandomFactory; 39 import static java.lang.Long.*; 40 41 public class BitTwiddle { 42 private static final int N = 1000; // # of repetitions per test 43 main(String args[])44 public static void main(String args[]) { 45 Random rnd = RandomFactory.getRandom(); 46 47 if (highestOneBit(0) != 0) 48 throw new RuntimeException("a"); 49 if (highestOneBit(-1) != MIN_VALUE) 50 throw new RuntimeException("b"); 51 if (highestOneBit(1) != 1) 52 throw new RuntimeException("c"); 53 54 if (lowestOneBit(0) != 0) 55 throw new RuntimeException("d"); 56 if (lowestOneBit(-1) != 1) 57 throw new RuntimeException("e"); 58 if (lowestOneBit(MIN_VALUE) != MIN_VALUE) 59 throw new RuntimeException("f"); 60 61 for (int i = 0; i < N; i++) { 62 long x = rnd.nextLong(); 63 64 String expected = new StringBuilder() 65 .append(leftpad(toBinaryString(x), 64)) 66 .reverse().toString(); 67 68 String actual = leftpad(toBinaryString(reverse(x)), 64); 69 70 if (!expected.equals(actual)) { 71 throw new RuntimeException("reverse: \n" + 72 expected + " \n" + actual); 73 } 74 } 75 76 for (int i = 0; i < N; i++) { 77 long x = rnd.nextLong(); 78 if (highestOneBit(x) != reverse(lowestOneBit(reverse(x)))) 79 throw new RuntimeException("g: " + toHexString(x)); 80 } 81 82 if (numberOfLeadingZeros(0) != SIZE) 83 throw new RuntimeException("h"); 84 if (numberOfLeadingZeros(-1) != 0) 85 throw new RuntimeException("i"); 86 if (numberOfLeadingZeros(1) != (SIZE - 1)) 87 throw new RuntimeException("j"); 88 if (numberOfLeadingZeros(Long.MAX_VALUE) != 1) 89 throw new RuntimeException("lzmax"); 90 if (numberOfLeadingZeros(Integer.MAX_VALUE + 1L) != (SIZE - 32)) 91 throw new RuntimeException("lz32"); 92 93 if (numberOfTrailingZeros(0) != SIZE) 94 throw new RuntimeException("k"); 95 if (numberOfTrailingZeros(1) != 0) 96 throw new RuntimeException("l"); 97 if (numberOfTrailingZeros(MIN_VALUE) != (SIZE - 1)) 98 throw new RuntimeException("m"); 99 100 for (int i = 0; i < N; i++) { 101 long x = rnd.nextLong(); 102 if (numberOfLeadingZeros(x) != numberOfTrailingZeros(reverse(x))) 103 throw new RuntimeException("n: " + toHexString(x)); 104 } 105 for (long i = 1, r = SIZE - 1; i != 0; i <<= 1, r--) { 106 if (numberOfLeadingZeros(i) != (int)r || 107 numberOfTrailingZeros(i) != (SIZE - (int)r - 1) || 108 numberOfLeadingZeros(i) != numberOfTrailingZeros(reverse(i))) { 109 throw new RuntimeException("lzx: " + toHexString(i)); 110 } 111 } 112 113 if (bitCount(0) != 0) 114 throw new RuntimeException("o"); 115 116 for (int i = 0; i < SIZE; i++) { 117 long pow2 = 1L << i; 118 if (bitCount(pow2) != 1) 119 throw new RuntimeException("p: " + i); 120 if (bitCount(pow2 -1) != i) 121 throw new RuntimeException("q: " + i); 122 } 123 124 for (int i = 0; i < N; i++) { 125 long x = rnd.nextLong(); 126 if (bitCount(x) != bitCount(reverse(x))) 127 throw new RuntimeException("r: " + toHexString(x)); 128 } 129 130 for (int i = 0; i < N; i++) { 131 long x = rnd.nextLong(); 132 int dist = rnd.nextInt(); 133 if (bitCount(x) != bitCount(rotateRight(x, dist))) 134 throw new RuntimeException("s: " + toHexString(x) + 135 toHexString(dist)); 136 if (bitCount(x) != bitCount(rotateLeft(x, dist))) 137 throw new RuntimeException("t: " + toHexString(x) + 138 toHexString(dist)); 139 if (rotateRight(x, dist) != rotateLeft(x, -dist)) 140 throw new RuntimeException("u: " + toHexString(x) + 141 toHexString(dist)); 142 if (rotateRight(x, -dist) != rotateLeft(x, dist)) 143 throw new RuntimeException("v: " + toHexString(x) + 144 toHexString(dist)); 145 } 146 147 if (signum(0) != 0 || signum(1) != 1 || signum(-1) != -1 148 || signum(MIN_VALUE) != -1 || signum(MAX_VALUE) != 1) 149 throw new RuntimeException("w"); 150 151 for (int i = 0; i < N; i++) { 152 long x = rnd.nextLong(); 153 int sign = (x < 0 ? -1 : (x == 0 ? 0 : 1)); 154 if (signum(x) != sign) 155 throw new RuntimeException("x: " + toHexString(x)); 156 } 157 158 if(reverseBytes(0xaabbccdd11223344L) != 0x44332211ddccbbaaL) 159 throw new RuntimeException("y"); 160 161 for (int i = 0; i < N; i++) { 162 long x = rnd.nextLong(); 163 if (bitCount(x) != bitCount(reverseBytes(x))) 164 throw new RuntimeException("z: " + toHexString(x)); 165 } 166 } 167 168 private static final String ZEROS = "0".repeat(64); leftpad(String s, int width)169 private static String leftpad(String s, int width) { 170 return ZEROS.substring(0, width - s.length()) + s; 171 } 172 } 173