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/* Copyright (c) 1996-2004, Adaptec Corporation
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the Adaptec Corporation nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __LZSTRBUF_H
#define __LZSTRBUF_H
/****************************************************************************
*
* Created: 1/19/2000
*
*****************************************************************************
*
* File Name: LzStrBuf.h
* Module: Generic
* Contributors: David Dillard
* Description: Contains the declaration of the LzInStreamBuf class.
* Version Control:
*
* $Revision$
* $NoKeywords: $
* $Log$
* Revision 1.1.1.1 2004-05-05 12:47:27 bap
* Imported upstream version 0.0.4.
*
*****************************************************************************/
/*** INCLUDES ***/
#include "dynsize.h"
//Class - LzInStreamBuf
//===========================================================================
//
//Description:
//
// This class decompresses an LZ77 compressed stream. The class could
// be improved by adding a constructor which allowed the caller to specify
// the number of index bits and length bits to use when decompressing the
// compressed input stream. Of course, this require some changes to the
// implementation of the class
//
//---------------------------------------------------------------------------
class LzInStreamBuf : public DynamicSizeInStreamBuf
{
public:
//
// Constructor
//
LzInStreamBuf(
std::istream &stream
);
//
// Destructor
//
~LzInStreamBuf();
//
// Fills the output buffer (this is an input stream so this call always
// fails).
//
int overflow(int ch = EOF)
{
return(EOF);
}
//
// Fills the streambuf's buffer with data.
//
int underflow();
private:
//
// Determines the next index into the compression window give the current
// index.
//
inline int NextWindowIndex(int index)
{
return(index & (WINDOW_SIZE - 1));
}
//
// Get the next bit from the compressed input stream.
//
int GetBit();
//
// Get the next number of specified bits from the compressed input stream.
//
unsigned long GetBits(
int bitCount
);
private:
//
// Private data used to implement the class.
//
enum
{
INDEX_BIT_COUNT = 11, // Bits to use for indices into text window
LENGTH_BIT_COUNT = 2, // Bits to use for length of an encoded phrase
WINDOW_SIZE = (1 << INDEX_BIT_COUNT),
BREAK_EVEN = ((1 + INDEX_BIT_COUNT + LENGTH_BIT_COUNT)/9),
END_OF_STREAM = 0
};
std::istream &m_Stream;
unsigned long m_BufSize;
unsigned long m_Rack;
int m_CurChar;
int m_CurrentIndex;
unsigned char *m_Window;
unsigned char m_Mask;
};
#endif
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