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 * @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
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
87 if (numberOfTrailingZeros(0) != SIZE)
88 throw new RuntimeException("k");
89 if (numberOfTrailingZeros(1) != 0)
90 throw new RuntimeException("l");
91 if (numberOfTrailingZeros(MIN_VALUE) != (SIZE - 1))
92 throw new RuntimeException("m");
93
94 for (int i = 0; i < N; i++) {
95 long x = rnd.nextLong();
96 if (numberOfLeadingZeros(x) != numberOfTrailingZeros(reverse(x)))
97 throw new RuntimeException("n: " + toHexString(x));
98 }
99
100 if (bitCount(0) != 0)
101 throw new RuntimeException("o");
102
103 for (int i = 0; i < SIZE; i++) {
104 long pow2 = 1L << i;
105 if (bitCount(pow2) != 1)
106 throw new RuntimeException("p: " + i);
107 if (bitCount(pow2 -1) != i)
108 throw new RuntimeException("q: " + i);
109 }
110
111 for (int i = 0; i < N; i++) {
112 long x = rnd.nextLong();
113 if (bitCount(x) != bitCount(reverse(x)))
114 throw new RuntimeException("r: " + toHexString(x));
115 }
116
117 for (int i = 0; i < N; i++) {
118 long x = rnd.nextLong();
119 int dist = rnd.nextInt();
120 if (bitCount(x) != bitCount(rotateRight(x, dist)))
121 throw new RuntimeException("s: " + toHexString(x) +
122 toHexString(dist));
123 if (bitCount(x) != bitCount(rotateLeft(x, dist)))
124 throw new RuntimeException("t: " + toHexString(x) +
125 toHexString(dist));
126 if (rotateRight(x, dist) != rotateLeft(x, -dist))
127 throw new RuntimeException("u: " + toHexString(x) +
128 toHexString(dist));
129 if (rotateRight(x, -dist) != rotateLeft(x, dist))
130 throw new RuntimeException("v: " + toHexString(x) +
131 toHexString(dist));
132 }
133
134 if (signum(0) != 0 || signum(1) != 1 || signum(-1) != -1
135 || signum(MIN_VALUE) != -1 || signum(MAX_VALUE) != 1)
136 throw new RuntimeException("w");
137
138 for (int i = 0; i < N; i++) {
139 long x = rnd.nextLong();
140 int sign = (x < 0 ? -1 : (x == 0 ? 0 : 1));
141 if (signum(x) != sign)
142 throw new RuntimeException("x: " + toHexString(x));
143 }
144
145 if(reverseBytes(0xaabbccdd11223344L) != 0x44332211ddccbbaaL)
146 throw new RuntimeException("y");
147
148 for (int i = 0; i < N; i++) {
149 long x = rnd.nextLong();
150 if (bitCount(x) != bitCount(reverseBytes(x)))
151 throw new RuntimeException("z: " + toHexString(x));
152 }
153 }
154
155 private static String leftpad(String s, int width) {
156 String r = s;
157 for (int c = 0; c < width - s.length(); c++) {
158 r = "0" + r;
159 }
160 return r;
161 }
162 }