| /* |
| * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package sun.security.util; |
| |
| import java.io.ByteArrayOutputStream; |
| import java.util.Arrays; |
| |
| /** |
| * A packed array of booleans. |
| * |
| * @author Joshua Bloch |
| * @author Douglas Hoover |
| */ |
| |
| public class BitArray { |
| |
| private byte[] repn; |
| private int length; |
| |
| private static final int BITS_PER_UNIT = 8; |
| |
| private static int subscript(int idx) { |
| return idx / BITS_PER_UNIT; |
| } |
| |
| private static int position(int idx) { // bits big-endian in each unit |
| return 1 << (BITS_PER_UNIT - 1 - (idx % BITS_PER_UNIT)); |
| } |
| |
| /** |
| * Creates a BitArray of the specified size, initialized to zeros. |
| */ |
| public BitArray(int length) throws IllegalArgumentException { |
| if (length < 0) { |
| throw new IllegalArgumentException("Negative length for BitArray"); |
| } |
| |
| this.length = length; |
| |
| repn = new byte[(length + BITS_PER_UNIT - 1)/BITS_PER_UNIT]; |
| } |
| |
| |
| /** |
| * Creates a BitArray of the specified size, initialized from the |
| * specified byte array. The most significant bit of a[0] gets |
| * index zero in the BitArray. The array a must be large enough |
| * to specify a value for every bit in the BitArray. In other words, |
| * 8*a.length <= length. |
| */ |
| public BitArray(int length, byte[] a) throws IllegalArgumentException { |
| |
| if (length < 0) { |
| throw new IllegalArgumentException("Negative length for BitArray"); |
| } |
| if (a.length * BITS_PER_UNIT < length) { |
| throw new IllegalArgumentException("Byte array too short to represent " + |
| "bit array of given length"); |
| } |
| |
| this.length = length; |
| |
| int repLength = ((length + BITS_PER_UNIT - 1)/BITS_PER_UNIT); |
| int unusedBits = repLength*BITS_PER_UNIT - length; |
| byte bitMask = (byte) (0xFF << unusedBits); |
| |
| /* |
| normalize the representation: |
| 1. discard extra bytes |
| 2. zero out extra bits in the last byte |
| */ |
| repn = new byte[repLength]; |
| System.arraycopy(a, 0, repn, 0, repLength); |
| if (repLength > 0) { |
| repn[repLength - 1] &= bitMask; |
| } |
| } |
| |
| /** |
| * Create a BitArray whose bits are those of the given array |
| * of Booleans. |
| */ |
| public BitArray(boolean[] bits) { |
| length = bits.length; |
| repn = new byte[(length + 7)/8]; |
| |
| for (int i=0; i < length; i++) { |
| set(i, bits[i]); |
| } |
| } |
| |
| |
| /** |
| * Copy constructor (for cloning). |
| */ |
| private BitArray(BitArray ba) { |
| length = ba.length; |
| repn = ba.repn.clone(); |
| } |
| |
| /** |
| * Returns the indexed bit in this BitArray. |
| */ |
| public boolean get(int index) throws ArrayIndexOutOfBoundsException { |
| if (index < 0 || index >= length) { |
| throw new ArrayIndexOutOfBoundsException(Integer.toString(index)); |
| } |
| |
| return (repn[subscript(index)] & position(index)) != 0; |
| } |
| |
| /** |
| * Sets the indexed bit in this BitArray. |
| */ |
| public void set(int index, boolean value) |
| throws ArrayIndexOutOfBoundsException { |
| if (index < 0 || index >= length) { |
| throw new ArrayIndexOutOfBoundsException(Integer.toString(index)); |
| } |
| int idx = subscript(index); |
| int bit = position(index); |
| |
| if (value) { |
| repn[idx] |= bit; |
| } else { |
| repn[idx] &= ~bit; |
| } |
| } |
| |
| /** |
| * Returns the length of this BitArray. |
| */ |
| public int length() { |
| return length; |
| } |
| |
| /** |
| * Returns a Byte array containing the contents of this BitArray. |
| * The bit stored at index zero in this BitArray will be copied |
| * into the most significant bit of the zeroth element of the |
| * returned byte array. The last byte of the returned byte array |
| * will be contain zeros in any bits that do not have corresponding |
| * bits in the BitArray. (This matters only if the BitArray's size |
| * is not a multiple of 8.) |
| */ |
| public byte[] toByteArray() { |
| return repn.clone(); |
| } |
| |
| public boolean equals(Object obj) { |
| if (obj == this) return true; |
| if (obj == null || !(obj instanceof BitArray)) return false; |
| |
| BitArray ba = (BitArray) obj; |
| |
| if (ba.length != length) return false; |
| |
| for (int i = 0; i < repn.length; i += 1) { |
| if (repn[i] != ba.repn[i]) return false; |
| } |
| return true; |
| } |
| |
| /** |
| * Return a boolean array with the same bit values a this BitArray. |
| */ |
| public boolean[] toBooleanArray() { |
| boolean[] bits = new boolean[length]; |
| |
| for (int i=0; i < length; i++) { |
| bits[i] = get(i); |
| } |
| return bits; |
| } |
| |
| /** |
| * Returns a hash code value for this bit array. |
| * |
| * @return a hash code value for this bit array. |
| */ |
| public int hashCode() { |
| int hashCode = 0; |
| |
| for (int i = 0; i < repn.length; i++) |
| hashCode = 31*hashCode + repn[i]; |
| |
| return hashCode ^ length; |
| } |
| |
| |
| public Object clone() { |
| return new BitArray(this); |
| } |
| |
| |
| private static final byte[][] NYBBLE = { |
| { (byte)'0',(byte)'0',(byte)'0',(byte)'0'}, |
| { (byte)'0',(byte)'0',(byte)'0',(byte)'1'}, |
| { (byte)'0',(byte)'0',(byte)'1',(byte)'0'}, |
| { (byte)'0',(byte)'0',(byte)'1',(byte)'1'}, |
| { (byte)'0',(byte)'1',(byte)'0',(byte)'0'}, |
| { (byte)'0',(byte)'1',(byte)'0',(byte)'1'}, |
| { (byte)'0',(byte)'1',(byte)'1',(byte)'0'}, |
| { (byte)'0',(byte)'1',(byte)'1',(byte)'1'}, |
| { (byte)'1',(byte)'0',(byte)'0',(byte)'0'}, |
| { (byte)'1',(byte)'0',(byte)'0',(byte)'1'}, |
| { (byte)'1',(byte)'0',(byte)'1',(byte)'0'}, |
| { (byte)'1',(byte)'0',(byte)'1',(byte)'1'}, |
| { (byte)'1',(byte)'1',(byte)'0',(byte)'0'}, |
| { (byte)'1',(byte)'1',(byte)'0',(byte)'1'}, |
| { (byte)'1',(byte)'1',(byte)'1',(byte)'0'}, |
| { (byte)'1',(byte)'1',(byte)'1',(byte)'1'} |
| }; |
| |
| private static final int BYTES_PER_LINE = 8; |
| |
| /** |
| * Returns a string representation of this BitArray. |
| */ |
| public String toString() { |
| ByteArrayOutputStream out = new ByteArrayOutputStream(); |
| |
| for (int i = 0; i < repn.length - 1; i++) { |
| out.write(NYBBLE[(repn[i] >> 4) & 0x0F], 0, 4); |
| out.write(NYBBLE[repn[i] & 0x0F], 0, 4); |
| |
| if (i % BYTES_PER_LINE == BYTES_PER_LINE - 1) { |
| out.write('\n'); |
| } else { |
| out.write(' '); |
| } |
| } |
| |
| // in last byte of repn, use only the valid bits |
| for (int i = BITS_PER_UNIT * (repn.length - 1); i < length; i++) { |
| out.write(get(i) ? '1' : '0'); |
| } |
| |
| return new String(out.toByteArray()); |
| |
| } |
| |
| public BitArray truncate() { |
| for (int i=length-1; i>=0; i--) { |
| if (get(i)) { |
| return new BitArray(i+1, Arrays.copyOf(repn, (i + BITS_PER_UNIT)/BITS_PER_UNIT)); |
| } |
| } |
| return new BitArray(1); |
| } |
| |
| } |