| //======================================================================== |
| // |
| // 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); |
| |
| 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; |
| int dataLen; |
| GBool limitStream; |
| }; |
| |
| #endif |