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arithcodec.h

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/***************************************************************************
    arithcodec.h  -  Definition of class ArithCodec
                             -------------------
    begin                : June 21 2002
    copyright            : (C) 2003 by Vojtìch Toman
    email                : vtoman@lit.cz
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

/* Based on code by:                                                       */


/***************************************************************************
Authors:        John Carpinelli   (johnfc@ecr.mu.oz.au)
                Wayne Salamonsen  (wbs@mundil.cs.mu.oz.au)
                Lang Stuiver      (langs@cs.mu.oz.au)

Purpose:        Data compression using revised arithmetic coding method.

Based on:       A. Moffat, R. Neal, I.H. Witten, "Arithmetic Coding Revisted",
                Proc. IEEE Data Compression Conference, Snowbird, Utah, 
                March 1995.

Copyright 1995 John Carpinelli and Wayne Salamonsen, All Rights Reserved.
Copyright 1996 Lang Stuiver, All Rights Reserved.

These programs are supplied free of charge for research purposes only,
and may not sold or incorporated into any commercial product.  There is
ABSOLUTELY NO WARRANTY of any sort, nor any undertaking that they are
fit for ANY PURPOSE WHATSOEVER.  Use them at your own risk.  If you do
happen to find a bug, or have modifications to suggest, please report
the same to Alistair Moffat, alistair@cs.mu.oz.au.  The copyright
notice above and this statement of conditions must remain an integral
part of each and every copy made of these files.
***************************************************************************/

#ifdef __GNUG__
#pragma interface
#endif

#ifndef ARITHCODEC_H
#define ARITHCODEC_H


#include "defs.h"
#include "arithcodecbase.h"



#define BYTE_SIZE       SIZEOF_CHAR*8


#define Half            ((CodeValue) 1 << (B_BITS-1))


#define Quarter         ((CodeValue) 1 << (B_BITS-2))


class ArithCodec : public ArithCodecBase
{
public:
  ArithCodec(void);

  //virtual void setOutputDevice(IODevice *device);

  //virtual void setInputDevice(IODevice *device);

  virtual void arithmeticEncode(FreqValue, FreqValue, FreqValue);

  virtual FreqValue arithmeticDecodeTarget(FreqValue);

  virtual void arithmeticDecode(FreqValue, FreqValue, FreqValue);

  //void binaryArithmeticEncode(FreqValue, FreqValue, int);
  //int binaryArithmeticDecode(FreqValue, FreqValue);

  virtual void startEncode(void);

  virtual void finishEncode(void);

  virtual void startDecode(void);

  virtual void finishDecode(void);

  virtual void startOutputtingBits(void);

  virtual void startInputtingBits(void);

  virtual void doneOutputtingBits(void);

  virtual void doneInputtingBits(void);

  virtual size_t numberOfOutputBytes(void);

protected:
  // Input decoding state

  CodeValue in_R;

  CodeValue in_D;

  DivValue in_r;

#ifdef FRUGAL_BITS

  CodeValue in_V;
#endif
  
  // Output encoding state

  long numberOfBytes;

  CodeValue out_L;

  CodeValue out_R;

  unsigned long outBitsOutstanding;

#ifdef FRUGAL_BITS

  int ignoreFirstBit;

  int firstMessage;

  CodeValue retrieveExcessInputBits(void);
#endif

  int inBuffer;

  unsigned char inBitPtr;

  int inGarbage;
  
  int outBuffer;

  int outBitsToGo;

}; //ArithCodec


#endif //ARITHCODEC_H

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