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/*
* @(#)Decompressor.java 1.7 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 1/13/98
* @author Jacek R. Ambroziak
* @group Sun Microsystems Laboratories
*/
package com.sun.java.help.search;
abstract class Decompressor
{
private static final int BitsInByte = 8;
private static final int NBits = 32;
private int _readByte;
private int _toRead = 0;
private int _path = 0;
abstract protected int getNextByte() throws Exception;
protected void initReading() {
_toRead = 0;
}
private int countZeroes() throws Exception
{
for (int count = 0;; _readByte = getNextByte(), _toRead = BitsInByte)
while (_toRead-- > 0)
if ((_readByte & (1 << _toRead)) != 0)
return count;
else
++count;
}
// reads 1 bit; returns non-0 for bit "1"
private int read() throws Exception
{
if (_toRead-- > 0)
return _readByte & (1 << _toRead);
else
{ // get next word
_toRead = BitsInByte - 1;
return (_readByte = getNextByte()) & 0x80;
}
}
public int read(int kBits) throws Exception
{
int shift = BitsInByte - _toRead;
if (kBits <= _toRead)
return ((_readByte<<shift) & 0xFF) >>> (shift + (_toRead-=kBits));
else
{
int result = _toRead > 0
? ((_readByte << shift) & 0xFF) >>> shift
: 0;
for (kBits -= _toRead; kBits >= BitsInByte; kBits -= BitsInByte)
result = (result << BitsInByte) | getNextByte();
if (kBits > 0)
return (result << kBits)
| ((_readByte = getNextByte()) >>> (_toRead = BitsInByte - kBits));
else
{
_toRead = 0;
return result;
}
}
}
public void beginIteration() {
_path = 0;
}
public boolean readNext(int k, CompressorIterator it) throws Exception
{
if (read() != 0)
{
it.value(_path | read(k));
return true;
}
else
for (int count = 1;; _readByte = getNextByte(), _toRead = BitsInByte)
while (_toRead-- > 0)
if ((_readByte & (1 << _toRead)) != 0)
{
int saved = _path;
_path = ((_path >>> (k + count) << count) | read(count)) << k;
if (_path != saved)
{
it.value(_path | read(k));
return true;
}
else
return false;
}
else
++count;
}
public void decode(int k, IntegerArray array) throws Exception
{
for (int path = 0;;)
if (read() != 0)
array.add(path | read(k));
else
{
int count = countZeroes() + 1;
int saved = path;
path = ((path >>> (k + count) << count) | read(count)) << k;
if (path != saved) // convention for end
array.add(path | read(k));
else
break;
}
}
public void ascDecode(int k, IntegerArray array) throws Exception
{
for (int path = 0, start = 0;;)
if (read() != 0)
array.add(start += path | read(k));
else
{
int count = countZeroes() + 1;
int saved = path;
path = ((path >>> (k + count) << count) | read(count)) << k;
if (path != saved) // convention for end
array.add(start += path | read(k));
else
break;
}
}
public int ascendingDecode(int k, int start, int[] array) throws Exception
{
int path = 0, index = 0;
LOOP:
while (true)
if (read() != 0)
array[index++] = (start += path | read(k));
else
for (int cnt = 0;; _readByte = getNextByte(), _toRead = BitsInByte)
while (_toRead-- > 0)
if ((_readByte & (1 << _toRead)) != 0)
{
++cnt;
int Path = ((path >>> (k + cnt) << cnt) | read(cnt)) << k;
if (Path != path)
{
array[index++] = (start += (path = Path) | read(k));
continue LOOP;
}
else
return index;
}
else
++cnt;
}
}
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