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/*
* @(#)BitBuffer.java 1.6 06/10/30
*
* Copyright (c) 2006 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
/**
* @date 2/17/98
* @author Jacek R. Ambroziak
* @group Sun Microsystems Laboratories
*/
/*
BitBuffer's client has to stick to a usage protocol:
- start with new or cleared BitBuffer
- do appends for a while
- finish w/ close()
*/
package com.sun.java.help.search;
import java.io.*;
class BitBuffer
{
private static final int InitSize = 256;
private static final int NBits = 32;
private static final int BitsInByte = 8;
private static final int BytesInInt = 4;
private int _avail = NBits;
private int _word = 0;
private int _free = 0;
private int _size = InitSize;
private int[] _array = new int[InitSize];
public void close()
{
if (_avail < NBits)
store(_word << _avail);
else
_avail = 0;
}
public void write(DataOutput out) throws IOException
{
for (int i = 0; i < _free - 1; i++)
out.writeInt(_array[i]);
int word = _array[_free - 1];
int bytes = BytesInInt - _avail/BitsInByte;
int shift = NBits;
while (bytes-- > 0)
out.writeByte((word >>> (shift -= BitsInByte)) & 0xFF);
}
public void clear()
{
_word = 0;
_avail = NBits;
_free = 0;
}
public int byteCount() {
return _free*BytesInInt - _avail/BitsInByte;
}
public int bitCount() {
return NBits*_free - _avail;
}
public void setFrom(BitBuffer rhs)
{
_word = rhs._word;
_avail = rhs._avail;
if ((_free = rhs._free) > _size)
_array = new int[_size = rhs._free];
System.arraycopy(rhs._array, 0, _array, 0, _free);
}
private void growArray(int newSize)
{
int[] newArray = new int[_size = newSize];
System.arraycopy(_array, 0, newArray, 0, _free);
_array = newArray;
}
private void store(int value)
{
if (_free == _size)
growArray(_size * 2);
_array[_free++] = value;
}
public void append(int bit)
{
_word = (_word << 1) | bit;
if (--_avail == 0)
{
store(_word);
_word = 0;
_avail = NBits;
}
}
public void append(int source, int kBits)
{
if (kBits < _avail)
{
_word = (_word << kBits) | source;
_avail -= kBits;
}
else if (kBits > _avail)
{
int leftover = kBits - _avail;
store((_word << _avail) | (source >>> leftover));
_word = source;
_avail = NBits - leftover;
}
else
{
store((_word << kBits) | source);
_word = 0;
_avail = NBits;
}
}
public void concatenate(BitBuffer bb)
{
if (NBits*(_size - _free) + _avail < bb.bitCount())
growArray(_free + bb._free + 1);
if (_avail == 0)
{
System.arraycopy(bb._array, 0, _array, _free, bb._free);
_avail = bb._avail;
_free += bb._free;
}
else
{
int tp = _free - 1; // target
int sp = 0; // source
do {
_array[tp++] |= bb._array[sp] >>> (NBits - _avail);
_array[tp] = bb._array[sp++] << _avail;
}
while (sp < bb._free);
_free += bb._free;
if ((_avail += bb._avail) >= NBits)
{
_avail -= NBits;
_free--;
}
}
}
}
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