TComBitStream.h

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/* The copyright in this software is being made available under the BSD
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 * granted under this license.
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 * Copyright (c) 2010-2017, ITU/ISO/IEC
 * All rights reserved.
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#ifndef __TCOMBITSTREAM__
#define __TCOMBITSTREAM__

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <stdint.h>
#include <vector>
#include <stdio.h>
#include "CommonDef.h"


// ====================================================================================================================
// Class definition
// ====================================================================================================================

class TComBitIf
{
public:
  virtual Void        writeAlignOne         () {};
  virtual Void        writeAlignZero        () {};
  virtual Void        write                 ( UInt uiBits, UInt uiNumberOfBits )  = 0;
  virtual Void        resetBits             ()                                    = 0;
  virtual UInt        getNumberOfWrittenBits() const = 0;
  virtual Int         getNumBitsUntilByteAligned() const = 0;
  virtual ~TComBitIf() {}
};

class TComOutputBitstream : public TComBitIf
{
  std::vector<uint8_t> m_fifo;

  UInt m_num_held_bits; 
  UChar m_held_bits; 
public:
  // create / destroy
  TComOutputBitstream();
  ~TComOutputBitstream();

  // interface for encoding
  Void        write           ( UInt uiBits, UInt uiNumberOfBits );

  Void        writeAlignOne   ();

  Void        writeAlignZero  ();

  Void resetBits() { assert(0); }

  // utility functions

  UChar* getByteStream() const;

  UInt getByteStreamLength();

  Void clear();

  Int getNumBitsUntilByteAligned() const { return (8 - m_num_held_bits) & 0x7; }

  UInt getNumberOfWrittenBits() const { return UInt(m_fifo.size()) * 8 + m_num_held_bits; }

  Void insertAt(const TComOutputBitstream& src, UInt pos);

  std::vector<uint8_t>& getFIFO() { return m_fifo; }

  UChar getHeldBits  ()          { return m_held_bits;          }

  //TComOutputBitstream& operator= (const TComOutputBitstream& src);
  const std::vector<uint8_t>& getFIFO() const { return m_fifo; }

  Void          addSubstream    ( TComOutputBitstream* pcSubstream );
  Void writeByteAlignment();

  Int countStartCodeEmulations();
};

class TComInputBitstream
{
protected:
  std::vector<uint8_t> m_fifo; 
  std::vector<UInt>    m_emulationPreventionByteLocation;

  UInt m_fifo_idx; 

  UInt m_num_held_bits;
  UChar m_held_bits;
  UInt  m_numBitsRead;

public:
  TComInputBitstream();
  virtual ~TComInputBitstream() { }
  TComInputBitstream(const TComInputBitstream &src);

  Void resetToStart();

  // interface for decoding
  Void        pseudoRead      ( UInt uiNumberOfBits, UInt& ruiBits );
  Void        read            ( UInt uiNumberOfBits, UInt& ruiBits );
  Void        readByte        ( UInt &ruiBits )
  {
    assert(m_fifo_idx < m_fifo.size());
    ruiBits = m_fifo[m_fifo_idx++];
  }

  Void        peekPreviousByte( UInt &byte )
  {
    assert(m_fifo_idx > 0);
    byte = m_fifo[m_fifo_idx - 1];
  }

  UInt        readOutTrailingBits ();
  UChar getHeldBits  ()          { return m_held_bits;          }
  TComOutputBitstream& operator= (const TComOutputBitstream& src);
  UInt  getByteLocation              ( )                     { return m_fifo_idx                    ; }

  // Peek at bits in word-storage. Used in determining if we have completed reading of current bitstream and therefore slice in LCEC.
  UInt        peekBits (UInt uiBits) { UInt tmp; pseudoRead(uiBits, tmp); return tmp; }

  // utility functions
  UInt read(UInt numberOfBits) { UInt tmp; read(numberOfBits, tmp); return tmp; }
  UInt     readByte() { UInt tmp; readByte( tmp ); return tmp; }
  UInt getNumBitsUntilByteAligned() { return m_num_held_bits & (0x7); }
  UInt getNumBitsLeft() { return 8*((UInt)m_fifo.size() - m_fifo_idx) + m_num_held_bits; }
  TComInputBitstream *extractSubstream( UInt uiNumBits ); // Read the nominated number of bits, and return as a bitstream.
  UInt  getNumBitsRead() { return m_numBitsRead; }
  UInt readByteAlignment();

  Void      pushEmulationPreventionByteLocation ( UInt pos )                         { m_emulationPreventionByteLocation.push_back( pos ); }
  UInt      numEmulationPreventionBytesRead     ()                                   { return (UInt) m_emulationPreventionByteLocation.size();    }
  const std::vector<UInt> &getEmulationPreventionByteLocation  () const              { return m_emulationPreventionByteLocation;           }
  UInt      getEmulationPreventionByteLocation  ( UInt idx )                         { return m_emulationPreventionByteLocation[ idx ];    }
  Void      clearEmulationPreventionByteLocation()                                   { m_emulationPreventionByteLocation.clear();          }
  Void      setEmulationPreventionByteLocation  ( const std::vector<UInt> &vec )     { m_emulationPreventionByteLocation = vec;            }

  const std::vector<uint8_t> &getFifo() const { return m_fifo; }
        std::vector<uint8_t> &getFifo()       { return m_fifo; }
};


#endif