JBig2_ArithDecoder.h

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// Copyright 2014 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
#ifndef CORE_FXCODEC_JBIG2_JBIG2_ARITHDECODER_H_
#define CORE_FXCODEC_JBIG2_JBIG2_ARITHDECODER_H_
 
#include <stdint.h>
 
#include "core/fxcrt/fx_memory_wrappers.h"
#include "core/fxcrt/unowned_ptr.h"
 
class CJBig2_BitStream;
struct JBig2ArithQe;
 
class JBig2ArithCtx {
 public:
  struct JBig2ArithQe {
    uint16_t Qe;
    uint8_t NMPS;
    uint8_t NLPS;
    bool bSwitch;
  };
 
  JBig2ArithCtx();
 
  int DecodeNLPS(const JBig2ArithQe& qe);
  int DecodeNMPS(const JBig2ArithQe& qe);
 
  unsigned int MPS() const { return m_MPS ? 1 : 0; }
  unsigned int I() const { return m_I; }
 
 private:
  bool m_MPS = false;
  unsigned int m_I = 0;
};
FX_DATA_PARTITION_EXCEPTION(JBig2ArithCtx);
 
class CJBig2_ArithDecoder {
 public:
  explicit CJBig2_ArithDecoder(CJBig2_BitStream* pStream);
  ~CJBig2_ArithDecoder();
 
  int Decode(JBig2ArithCtx* pCX);
 
  bool IsComplete() const { return m_Complete; }
 
 private:
  enum class StreamState : uint8_t {
    kDataAvailable,
    kDecodingFinished,
    kLooping,
  };
 
  void BYTEIN();
  void ReadValueA();
 
  bool m_Complete = false;
  StreamState m_State = StreamState::kDataAvailable;
  uint8_t m_B;
  unsigned int m_C;
  unsigned int m_A;
  unsigned int m_CT;
  UnownedPtr<CJBig2_BitStream> const m_pStream;
};
 
#endif  // CORE_FXCODEC_JBIG2_JBIG2_ARITHDECODER_H_