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ZPCodec.h

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//C-  -*- C++ -*-
//C- -------------------------------------------------------------------
//C- DjVuLibre-3.5
//C- Copyright (c) 2002  Leon Bottou and Yann Le Cun.
//C- Copyright (c) 2001  AT&T
//C-
//C- This software is subject to, and may be distributed under, the
//C- GNU General Public License, Version 2. The license should have
//C- accompanied the software or you may obtain a copy of the license
//C- from the Free Software Foundation at http://www.fsf.org .
//C-
//C- This program is distributed in the hope that it will be useful,
//C- but WITHOUT ANY WARRANTY; without even the implied warranty of
//C- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//C- GNU General Public License for more details.
//C- 
//C- DjVuLibre-3.5 is derived from the DjVu(r) Reference Library
//C- distributed by Lizardtech Software.  On July 19th 2002, Lizardtech 
//C- Software authorized us to replace the original DjVu(r) Reference 
//C- Library notice by the following text (see doc/lizard2002.djvu):
//C-
//C-  ------------------------------------------------------------------
//C- | DjVu (r) Reference Library (v. 3.5)
//C- | Copyright (c) 1999-2001 LizardTech, Inc. All Rights Reserved.
//C- | The DjVu Reference Library is protected by U.S. Pat. No.
//C- | 6,058,214 and patents pending.
//C- |
//C- | This software is subject to, and may be distributed under, the
//C- | GNU General Public License, Version 2. The license should have
//C- | accompanied the software or you may obtain a copy of the license
//C- | from the Free Software Foundation at http://www.fsf.org .
//C- |
//C- | The computer code originally released by LizardTech under this
//C- | license and unmodified by other parties is deemed "the LIZARDTECH
//C- | ORIGINAL CODE."  Subject to any third party intellectual property
//C- | claims, LizardTech grants recipient a worldwide, royalty-free, 
//C- | non-exclusive license to make, use, sell, or otherwise dispose of 
//C- | the LIZARDTECH ORIGINAL CODE or of programs derived from the 
//C- | LIZARDTECH ORIGINAL CODE in compliance with the terms of the GNU 
//C- | General Public License.   This grant only confers the right to 
//C- | infringe patent claims underlying the LIZARDTECH ORIGINAL CODE to 
//C- | the extent such infringement is reasonably necessary to enable 
//C- | recipient to make, have made, practice, sell, or otherwise dispose 
//C- | of the LIZARDTECH ORIGINAL CODE (or portions thereof) and not to 
//C- | any greater extent that may be necessary to utilize further 
//C- | modifications or combinations.
//C- |
//C- | The LIZARDTECH ORIGINAL CODE is provided "AS IS" WITHOUT WARRANTY
//C- | OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
//C- | TO ANY WARRANTY OF NON-INFRINGEMENT, OR ANY IMPLIED WARRANTY OF
//C- | MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
//C- +------------------------------------------------------------------
// 
// $Id: ZPCodec.h,v 1.9 2003/11/07 22:08:22 leonb Exp $
// $Name: release_3_5_15 $

#ifndef _ZPCODEC_H
#define _ZPCODEC_H
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#if NEED_GNUG_PRAGMAS
# pragma interface
#endif

// From: Leon Bottou, 1/31/2002
// Almost equal to my initial code.

#include "GContainer.h"

#ifdef HAVE_NAMESPACES
namespace DJVU {
# ifdef NOT_DEFINED // Just to fool emacs c++ mode
}
#endif
#endif

class ByteStream;





typedef unsigned char  BitContext;


class ZPCodec : public GPEnabled {
protected:
  ZPCodec (GP<ByteStream> gbs, const bool encoding, const bool djvucompat=false);
public:
  class Encode;
  class Decode;

  ~ZPCodec();
  static GP<ZPCodec> create(
     GP<ByteStream> gbs, const bool encoding, const bool djvucompat=false);

  void encoder(int bit, BitContext &ctx);

  int  decoder(BitContext &ctx);

  void encoder(int bit);

  int  decoder(void);
#ifdef ZPCODEC_BITCOUNT

  int bitcount;
#endif
  // Table management (advanced stuff)
  struct Table { 
    unsigned short p;
    unsigned short m;
    BitContext     up;
    BitContext     dn;
  };
  void newtable(ZPCodec::Table *table);
  BitContext state(float prob1);
  // Non-adaptive encoder/decoder
  void encoder_nolearn(int pix, BitContext &ctx);
  int  decoder_nolearn(BitContext &ctx);
  inline int  IWdecoder(void);
  inline void IWencoder(const bool bit);
protected:
  // coder status
  GP<ByteStream> gbs;           // Where the data goes/comes from
  ByteStream *bs;               // Where the data goes/comes from
  const bool encoding;          // Direction (0=decoding, 1=encoding)
  unsigned char byte;
  unsigned char scount;
  unsigned char delay;
  unsigned int  a;
  unsigned int  code;
  unsigned int  fence;
  unsigned int  subend;
  unsigned int  buffer;
  unsigned int  nrun;
  // table
  unsigned int  p[256];
  unsigned int  m[256];
  BitContext    up[256];
  BitContext    dn[256];
  // machine independent ffz
  char          ffzt[256];
  // encoder private
  void einit (void);
  void eflush (void);
  void outbit(int bit);
  void zemit(int b);
  void encode_mps(BitContext &ctx, unsigned int z);
  void encode_lps(BitContext &ctx, unsigned int z);
  void encode_mps_simple(unsigned int z);
  void encode_lps_simple(unsigned int z);
  void encode_mps_nolearn(unsigned int z);
  void encode_lps_nolearn(unsigned int z);
  // decoder private
  void dinit(void);
  void preload(void);
  int  ffz(unsigned int x);
  int  decode_sub(BitContext &ctx, unsigned int z);
  int  decode_sub_simple(int mps, unsigned int z);
  int  decode_sub_nolearn(int mps, unsigned int z);
private:
  // no copy allowed (hate c++)
  ZPCodec(const ZPCodec&);
  ZPCodec& operator=(const ZPCodec&);
#ifdef ZPCODEC_FRIEND
  friend ZPCODEC_FRIEND;
#endif
};






// INLINE CODE

inline void 
ZPCodec::encoder(int bit, BitContext &ctx) 
{
  unsigned int z = a + p[ctx];
  if (bit != (ctx & 1))
  {
    encode_lps(ctx, z);
  }else if (z >= 0x8000)
  {
    encode_mps(ctx, z);
  }else
  {
    a = z;
  }
}

inline int
ZPCodec::IWdecoder(void)
{
  return decode_sub_simple(0,0x8000 + ((a+a+a) >> 3));
}

inline int
ZPCodec::decoder(BitContext &ctx) 
{
  unsigned int z = a + p[ctx];
  if (z <= fence) 
    { a = z; return (ctx&1); } 
  return decode_sub(ctx, z);
}

inline void 
ZPCodec::encoder_nolearn(int bit, BitContext &ctx) 
{
  unsigned int z = a + p[ctx];
  if (bit != (ctx & 1))
    encode_lps_nolearn(z);
  else if (z >= 0x8000)
    encode_mps_nolearn(z);
  else
    a = z;
}

inline int
ZPCodec::decoder_nolearn(BitContext &ctx) 
{
  unsigned int z = a + p[ctx];
  if (z <= fence) 
    { a = z; return (ctx&1); } 
  return decode_sub_nolearn( (ctx&1), z);
}

inline void 
ZPCodec::encoder(int bit)
{
  if (bit)
    encode_lps_simple(0x8000 + (a>>1));
  else
    encode_mps_simple(0x8000 + (a>>1));
}

inline int
ZPCodec::decoder(void)
{
  return decode_sub_simple(0, 0x8000 + (a>>1));
}

inline void
ZPCodec::IWencoder(const bool bit)
{
  const int z = 0x8000 + ((a+a+a) >> 3);
  if (bit)
  {
    encode_lps_simple(z);
  }else
  {
    encode_mps_simple(z);
  }
}

// ------------ ADDITIONAL DOCUMENTATION


// ------------ THE END

#ifdef HAVE_NAMESPACES
}
# ifndef NOT_USING_DJVU_NAMESPACE
using namespace DJVU;
# endif
#endif
#endif

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