//========================================================================

//

// JArithmeticDecoder.h

//

// Arithmetic decoder used by the JBIG2 and JPEG2000 decoders.

//

// Copyright 2002-2004 Glyph & Cog, LLC

//

//========================================================================

//========================================================================

//

// Modified under the Poppler project - http://poppler.freedesktop.org

//

// All changes made under the Poppler project to this file are licensed

// under GPL version 2 or later

//

// Copyright (C) 2018, 2021, 2026 Albert Astals Cid <aacid@kde.org>

// Copyright (C) 2019 Volker Krause <vkrause@kde.org>

// Copyright (C) 2020 Even Rouault <even.rouault@spatialys.com>

//

// To see a description of the changes please see the Changelog file that

// came with your tarball or type make ChangeLog if you are building from git

//

//========================================================================

#ifndef JARITHMETICDECODER_H

#define JARITHMETICDECODER_H

class Stream;

//------------------------------------------------------------------------

// JArithmeticDecoderStats

//------------------------------------------------------------------------

class JArithmeticDecoderStats

{

public:

    explicit JArithmeticDecoderStats(int contextSizeA);

    ~JArithmeticDecoderStats();

    JArithmeticDecoderStats(const JArithmeticDecoderStats &) = delete;

    JArithmeticDecoderStats &operator=(const JArithmeticDecoderStats &) = delete;

    std::unique_ptr<JArithmeticDecoderStats> copy() const;

    void resetContext();

    int getContextSize() const { return contextSize; }

    void copyFrom(const JArithmeticDecoderStats &stats);

    void setEntry(unsigned int cx, int i, int mps);

    bool isValid() const { return cxTab != nullptr; }

private:

    unsigned char *cxTab; // cxTab[cx] = (i[cx] << 1) + mps[cx]

    int contextSize;

    friend class JArithmeticDecoder;

};

//------------------------------------------------------------------------

// JArithmeticDecoder

//------------------------------------------------------------------------

class JArithmeticDecoder

{

public:

    JArithmeticDecoder();

    ~JArithmeticDecoder();

    JArithmeticDecoder(const JArithmeticDecoder &) = delete;

    JArithmeticDecoder &operator=(const JArithmeticDecoder &) = delete;

    void setStream(Stream *strA)

    {

        str = strA;

        dataLen = 0;

        limitStream = false;

    }

    void setStream(Stream *strA, int dataLenA)

    {

        str = strA;

        dataLen = dataLenA;

        limitStream = true;

    }

    // 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(unsigned int context, JArithmeticDecoderStats *stats);

    // Decode eight bits.

    int decodeByte(unsigned int context, JArithmeticDecoderStats *stats);

    // Returns false for OOB, otherwise sets *<x> and returns true.

    bool decodeInt(int *x, JArithmeticDecoderStats *stats);

    unsigned int decodeIAID(unsigned int codeLen, JArithmeticDecoderStats *stats);

    void resetByteCounter() { nBytesRead = 0; }

    unsigned int getByteCounter() const { return nBytesRead; }

    bool getReadPastEndOfStream() const { return readPastEndOfStream; }

private:

    unsigned int readByte();

    int decodeIntBit(JArithmeticDecoderStats *stats);

    void byteIn();

    static const unsigned int qeTab[47];

    static const int nmpsTab[47];

    static const int nlpsTab[47];

    static const int switchTab[47];

    unsigned int buf0, buf1;

    unsigned int c, a;

    int ct;

    unsigned int prev; // for the integer decoder

    Stream *str;

    unsigned int nBytesRead;

    int dataLen;

    bool limitStream;

    bool readPastEndOfStream = false;

};

#endif