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 int 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.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
61 String expected = new StringBuilder()
62 .append(leftpad(toBinaryString(x), 32))
63 .reverse().toString();
64
65 String actual = leftpad(toBinaryString(reverse(x)), 32);
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 int x = rnd.nextInt();
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 int x = rnd.nextInt();
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 int pow2 = 1 << 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 int x = rnd.nextInt();
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 int x = rnd.nextInt();
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 int x = rnd.nextInt();
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(0xaabbccdd) != 0xddccbbaa)
145 throw new RuntimeException("y");
146
147 for (int i = 0; i < N; i++) {
148 int x = rnd.nextInt();
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 }