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| 1 | /* | ||
| 2 | * Copyright (c) 1997, 2006, 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. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package sun.security.util; | ||
| 27 | |||
| 28 | import java.io.ByteArrayOutputStream; | ||
| 29 | import java.util.Arrays; | ||
| 30 | |||
| 31 | /** | ||
| 32 | * A packed array of booleans. | ||
| 33 | * | ||
| 34 | * @author Joshua Bloch | ||
| 35 | * @author Douglas Hoover | ||
| 36 | */ | ||
| 37 | |||
| 38 | public class BitArray { | ||
| 39 | |||
| 40 | private byte[] repn; | ||
| 41 | private int length; | ||
| 42 | |||
| 43 | private static final int BITS_PER_UNIT = 8; | ||
| 44 | |||
| 45 | private static int subscript(int idx) { | ||
| 46 | return idx / BITS_PER_UNIT; | ||
| 47 | } | ||
| 48 | |||
| 49 | private static int position(int idx) { // bits big-endian in each unit | ||
| 50 | return 1 << (BITS_PER_UNIT - 1 - (idx % BITS_PER_UNIT)); | ||
| 51 | } | ||
| 52 | |||
| 53 | /** | ||
| 54 | * Creates a BitArray of the specified size, initialized to zeros. | ||
| 55 | */ | ||
| 56 | public BitArray(int length) throws IllegalArgumentException { | ||
| 57 | if (length < 0) { | ||
| 58 | throw new IllegalArgumentException("Negative length for BitArray"); | ||
| 59 | } | ||
| 60 | |||
| 61 | this.length = length; | ||
| 62 | |||
| 63 | repn = new byte[(length + BITS_PER_UNIT - 1)/BITS_PER_UNIT]; | ||
| 64 | } | ||
| 65 | |||
| 66 | |||
| 67 | /** | ||
| 68 | * Creates a BitArray of the specified size, initialized from the | ||
| 69 | * specified byte array. The most significant bit of a[0] gets | ||
| 70 | * index zero in the BitArray. The array a must be large enough | ||
| 71 | * to specify a value for every bit in the BitArray. In other words, | ||
| 72 | * 8*a.length <= length. | ||
| 73 | */ | ||
| 74 | public BitArray(int length, byte[] a) throws IllegalArgumentException { | ||
| 75 | |||
| 76 | if (length < 0) { | ||
| 77 | throw new IllegalArgumentException("Negative length for BitArray"); | ||
| 78 | } | ||
| 79 | if (a.length * BITS_PER_UNIT < length) { | ||
| 80 | throw new IllegalArgumentException("Byte array too short to represent " + | ||
| 81 | "bit array of given length"); | ||
| 82 | } | ||
| 83 | |||
| 84 | this.length = length; | ||
| 85 | |||
| 86 | int repLength = ((length + BITS_PER_UNIT - 1)/BITS_PER_UNIT); | ||
| 87 | int unusedBits = repLength*BITS_PER_UNIT - length; | ||
| 88 | byte bitMask = (byte) (0xFF << unusedBits); | ||
| 89 | |||
| 90 | /* | ||
| 91 | normalize the representation: | ||
| 92 | 1. discard extra bytes | ||
| 93 | 2. zero out extra bits in the last byte | ||
| 94 | */ | ||
| 95 | repn = new byte[repLength]; | ||
| 96 | System.arraycopy(a, 0, repn, 0, repLength); | ||
| 97 | if (repLength > 0) { | ||
| 98 | repn[repLength - 1] &= bitMask; | ||
| 99 | } | ||
| 100 | } | ||
| 101 | |||
| 102 | /** | ||
| 103 | * Create a BitArray whose bits are those of the given array | ||
| 104 | * of Booleans. | ||
| 105 | */ | ||
| 106 | public BitArray(boolean[] bits) { | ||
| 107 | length = bits.length; | ||
| 108 | repn = new byte[(length + 7)/8]; | ||
| 109 | |||
| 110 | for (int i=0; i < length; i++) { | ||
| 111 | set(i, bits[i]); | ||
| 112 | } | ||
| 113 | } | ||
| 114 | |||
| 115 | |||
| 116 | /** | ||
| 117 | * Copy constructor (for cloning). | ||
| 118 | */ | ||
| 119 | private BitArray(BitArray ba) { | ||
| 120 | length = ba.length; | ||
| 121 | repn = ba.repn.clone(); | ||
| 122 | } | ||
| 123 | |||
| 124 | /** | ||
| 125 | * Returns the indexed bit in this BitArray. | ||
| 126 | */ | ||
| 127 | public boolean get(int index) throws ArrayIndexOutOfBoundsException { | ||
| 128 | if (index < 0 || index >= length) { | ||
| 129 | throw new ArrayIndexOutOfBoundsException(Integer.toString(index)); | ||
| 130 | } | ||
| 131 | |||
| 132 | return (repn[subscript(index)] & position(index)) != 0; | ||
| 133 | } | ||
| 134 | |||
| 135 | /** | ||
| 136 | * Sets the indexed bit in this BitArray. | ||
| 137 | */ | ||
| 138 | public void set(int index, boolean value) | ||
| 139 | throws ArrayIndexOutOfBoundsException { | ||
| 140 | if (index < 0 || index >= length) { | ||
| 141 | throw new ArrayIndexOutOfBoundsException(Integer.toString(index)); | ||
| 142 | } | ||
| 143 | int idx = subscript(index); | ||
| 144 | int bit = position(index); | ||
| 145 | |||
| 146 | if (value) { | ||
| 147 | repn[idx] |= bit; | ||
| 148 | } else { | ||
| 149 | repn[idx] &= ~bit; | ||
| 150 | } | ||
| 151 | } | ||
| 152 | |||
| 153 | /** | ||
| 154 | * Returns the length of this BitArray. | ||
| 155 | */ | ||
| 156 | public int length() { | ||
| 157 | return length; | ||
| 158 | } | ||
| 159 | |||
| 160 | /** | ||
| 161 | * Returns a Byte array containing the contents of this BitArray. | ||
| 162 | * The bit stored at index zero in this BitArray will be copied | ||
| 163 | * into the most significant bit of the zeroth element of the | ||
| 164 | * returned byte array. The last byte of the returned byte array | ||
| 165 | * will be contain zeros in any bits that do not have corresponding | ||
| 166 | * bits in the BitArray. (This matters only if the BitArray's size | ||
| 167 | * is not a multiple of 8.) | ||
| 168 | */ | ||
| 169 | public byte[] toByteArray() { | ||
| 170 | return repn.clone(); | ||
| 171 | } | ||
| 172 | |||
| 173 | public boolean equals(Object obj) { | ||
| 174 | if (obj == this) return true; | ||
| 175 | if (obj == null || !(obj instanceof BitArray)) return false; | ||
| 176 | |||
| 177 | BitArray ba = (BitArray) obj; | ||
| 178 | |||
| 179 | if (ba.length != length) return false; | ||
| 180 | |||
| 181 | for (int i = 0; i < repn.length; i += 1) { | ||
| 182 | if (repn[i] != ba.repn[i]) return false; | ||
| 183 | } | ||
| 184 | return true; | ||
| 185 | } | ||
| 186 | |||
| 187 | /** | ||
| 188 | * Return a boolean array with the same bit values a this BitArray. | ||
| 189 | */ | ||
| 190 | public boolean[] toBooleanArray() { | ||
| 191 | boolean[] bits = new boolean[length]; | ||
| 192 | |||
| 193 | for (int i=0; i < length; i++) { | ||
| 194 | bits[i] = get(i); | ||
| 195 | } | ||
| 196 | return bits; | ||
| 197 | } | ||
| 198 | |||
| 199 | /** | ||
| 200 | * Returns a hash code value for this bit array. | ||
| 201 | * | ||
| 202 | * @return a hash code value for this bit array. | ||
| 203 | */ | ||
| 204 | public int hashCode() { | ||
| 205 | int hashCode = 0; | ||
| 206 | |||
| 207 | for (int i = 0; i < repn.length; i++) | ||
| 208 | hashCode = 31*hashCode + repn[i]; | ||
| 209 | |||
| 210 | return hashCode ^ length; | ||
| 211 | } | ||
| 212 | |||
| 213 | |||
| 214 | public Object clone() { | ||
| 215 | return new BitArray(this); | ||
| 216 | } | ||
| 217 | |||
| 218 | |||
| 219 | private static final byte[][] NYBBLE = { | ||
| 220 | { (byte)'0',(byte)'0',(byte)'0',(byte)'0'}, | ||
| 221 | { (byte)'0',(byte)'0',(byte)'0',(byte)'1'}, | ||
| 222 | { (byte)'0',(byte)'0',(byte)'1',(byte)'0'}, | ||
| 223 | { (byte)'0',(byte)'0',(byte)'1',(byte)'1'}, | ||
| 224 | { (byte)'0',(byte)'1',(byte)'0',(byte)'0'}, | ||
| 225 | { (byte)'0',(byte)'1',(byte)'0',(byte)'1'}, | ||
| 226 | { (byte)'0',(byte)'1',(byte)'1',(byte)'0'}, | ||
| 227 | { (byte)'0',(byte)'1',(byte)'1',(byte)'1'}, | ||
| 228 | { (byte)'1',(byte)'0',(byte)'0',(byte)'0'}, | ||
| 229 | { (byte)'1',(byte)'0',(byte)'0',(byte)'1'}, | ||
| 230 | { (byte)'1',(byte)'0',(byte)'1',(byte)'0'}, | ||
| 231 | { (byte)'1',(byte)'0',(byte)'1',(byte)'1'}, | ||
| 232 | { (byte)'1',(byte)'1',(byte)'0',(byte)'0'}, | ||
| 233 | { (byte)'1',(byte)'1',(byte)'0',(byte)'1'}, | ||
| 234 | { (byte)'1',(byte)'1',(byte)'1',(byte)'0'}, | ||
| 235 | { (byte)'1',(byte)'1',(byte)'1',(byte)'1'} | ||
| 236 | }; | ||
| 237 | |||
| 238 | private static final int BYTES_PER_LINE = 8; | ||
| 239 | |||
| 240 | /** | ||
| 241 | * Returns a string representation of this BitArray. | ||
| 242 | */ | ||
| 243 | public String toString() { | ||
| 244 | ByteArrayOutputStream out = new ByteArrayOutputStream(); | ||
| 245 | |||
| 246 | for (int i = 0; i < repn.length - 1; i++) { | ||
| 247 | out.write(NYBBLE[(repn[i] >> 4) & 0x0F], 0, 4); | ||
| 248 | out.write(NYBBLE[repn[i] & 0x0F], 0, 4); | ||
| 249 | |||
| 250 | if (i % BYTES_PER_LINE == BYTES_PER_LINE - 1) { | ||
| 251 | out.write('\n'); | ||
| 252 | } else { | ||
| 253 | out.write(' '); | ||
| 254 | } | ||
| 255 | } | ||
| 256 | |||
| 257 | // in last byte of repn, use only the valid bits | ||
| 258 | for (int i = BITS_PER_UNIT * (repn.length - 1); i < length; i++) { | ||
| 259 | out.write(get(i) ? '1' : '0'); | ||
| 260 | } | ||
| 261 | |||
| 262 | return new String(out.toByteArray()); | ||
| 263 | |||
| 264 | } | ||
| 265 | |||
| 266 | public BitArray truncate() { | ||
| 267 | for (int i=length-1; i>=0; i--) { | ||
| 268 | if (get(i)) { | ||
| 269 | return new BitArray(i+1, Arrays.copyOf(repn, (i + BITS_PER_UNIT)/BITS_PER_UNIT)); | ||
| 270 | } | ||
| 271 | } | ||
| 272 | return new BitArray(1); | ||
| 273 | } | ||
| 274 | |||
| 275 | } | ||