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//========================================================================
//
// JArithmeticDecoder.h
//
// Arithmetic decoder used by the JBIG2 and JPEG2000 decoders.
//
// Copyright 2002-2004 Glyph & Cog, LLC
//
//========================================================================
#ifndef JARITHMETICDECODER_H
#define JARITHMETICDECODER_H
#ifdef USE_GCC_PRAGMAS
#pragma interface
#endif
#include "goo/gtypes.h"
class Stream;
//------------------------------------------------------------------------
// JArithmeticDecoderStats
//------------------------------------------------------------------------
class JArithmeticDecoderStats {
public:
JArithmeticDecoderStats(int contextSizeA);
~JArithmeticDecoderStats();
JArithmeticDecoderStats *copy();
void reset();
int getContextSize() { return contextSize; }
void copyFrom(JArithmeticDecoderStats *stats);
void setEntry(Guint cx, int i, int mps);
private:
Guchar *cxTab; // cxTab[cx] = (i[cx] << 1) + mps[cx]
int contextSize;
friend class JArithmeticDecoder;
};
//------------------------------------------------------------------------
// JArithmeticDecoder
//------------------------------------------------------------------------
class JArithmeticDecoder {
public:
JArithmeticDecoder();
~JArithmeticDecoder();
void setStream(Stream *strA)
{ str = strA; dataLen = 0; limitStream = gFalse; }
void setStream(Stream *strA, int dataLenA)
{ str = strA; dataLen = dataLenA; limitStream = gTrue; }
// Start decoding on a new stream. This fills the byte buffers and
// runs INITDEC.
void start();
// Restart decoding on an interrupted stream. This refills the
// buffers if needed, but does not run INITDEC. (This is used in
// JPEG 2000 streams when codeblock data is split across multiple
// packets/layers.)
void restart(int dataLenA);
// Read any leftover data in the stream.
void cleanup();
// Decode one bit.
int decodeBit(Guint context, JArithmeticDecoderStats *stats);
// Decode eight bits.
int decodeByte(Guint context, JArithmeticDecoderStats *stats);
// Returns false for OOB, otherwise sets *<x> and returns true.
GBool decodeInt(int *x, JArithmeticDecoderStats *stats);
Guint decodeIAID(Guint codeLen,
JArithmeticDecoderStats *stats);
void resetByteCounter() { nBytesRead = 0; }
Guint getByteCounter() { return nBytesRead; }
private:
Guint readByte();
int decodeIntBit(JArithmeticDecoderStats *stats);
void byteIn();
static Guint qeTab[47];
static int nmpsTab[47];
static int nlpsTab[47];
static int switchTab[47];
Guint buf0, buf1;
Guint c, a;
int ct;
Guint prev; // for the integer decoder
Stream *str;
Guint nBytesRead;
int dataLen;
GBool limitStream;
};
#endif
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