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/** \file     DecSlice.cpp
    \brief    slice decoder class
*/

#include "DecSlice.h"
#include "CommonLib/UnitTools.h"
#include "CommonLib/dtrace_next.h"

#include <vector>

//! \ingroup DecoderLib
//! \{

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

DecSlice::DecSlice()
{
}

DecSlice::~DecSlice()
{
}

void DecSlice::create()
{
}

void DecSlice::destroy()
{
}

void DecSlice::init( CABACDecoder* cabacDecoder, DecCu* pcCuDecoder )
{
  m_CABACDecoder    = cabacDecoder;
  m_pcCuDecoder     = pcCuDecoder;
}

void DecSlice::decompressSlice( Slice* slice, InputBitstream* bitstream, int debugCTU )
{
  //-- For time output for each slice
  slice->startProcessingTimer();

  const SPS*     sps          = slice->getSPS();
  Picture*       pic          = slice->getPic();
  CABACReader&   cabacReader  = *m_CABACDecoder->getCABACReader( 0 );

  // setup coding structure
  CodingStructure& cs = *pic->cs;
  cs.slice            = slice;
  cs.sps              = sps;
  cs.pps              = slice->getPPS();
  memcpy(cs.alfApss, slice->getAlfAPSs(), sizeof(cs.alfApss));

  cs.lmcsAps          = slice->getPicHeader()->getLmcsAPS();
  cs.scalinglistAps   = slice->getPicHeader()->getScalingListAPS();

  cs.pcv              = slice->getPPS()->pcv;
  cs.chromaQpAdj      = 0;

  cs.picture->resizeSAO(cs.pcv->sizeInCtus, 0);

  cs.resetPrevPLT(cs.prevPLT);

  if (slice->getFirstCtuRsAddrInSlice() == 0)
  {
    cs.picture->resizeAlfCtuEnableFlag( cs.pcv->sizeInCtus );
    cs.picture->resizeAlfCtbFilterIndex(cs.pcv->sizeInCtus);
    cs.picture->resizeAlfCtuAlternative( cs.pcv->sizeInCtus );
  }

  const unsigned numSubstreams = slice->getNumberOfSubstreamSizes() + 1;

  // init each couple {EntropyDecoder, Substream}
  // Table of extracted substreams.
  std::vector<InputBitstream*> ppcSubstreams( numSubstreams );
  for( unsigned idx = 0; idx < numSubstreams; idx++ )
  {
    ppcSubstreams[idx] = bitstream->extractSubstream( idx+1 < numSubstreams ? ( slice->getSubstreamSize(idx) << 3 ) : bitstream->getNumBitsLeft() );
  }

  const unsigned  widthInCtus             = cs.pcv->widthInCtus;
  const bool      wavefrontsEnabled       = cs.pps->getEntropyCodingSyncEnabledFlag();

  cabacReader.initBitstream( ppcSubstreams[0] );
  cabacReader.initCtxModels( *slice );

  // Quantization parameter
    pic->m_prevQP[0] = pic->m_prevQP[1] = slice->getSliceQp();
  CHECK( pic->m_prevQP[0] == std::numeric_limits<int>::max(), "Invalid previous QP" );

  DTRACE( g_trace_ctx, D_HEADER, "=========== POC: %d ===========\n", slice->getPOC() );


  // for every CTU in the slice segment...
  unsigned subStrmId = 0;
  for( unsigned ctuIdx = 0; ctuIdx < slice->getNumCtuInSlice(); ctuIdx++ )
  {
    const unsigned  ctuRsAddr       = slice->getCtuAddrInSlice(ctuIdx);
    const unsigned  ctuXPosInCtus   = ctuRsAddr % widthInCtus;
    const unsigned  ctuYPosInCtus   = ctuRsAddr / widthInCtus;    
    const unsigned  tileColIdx      = slice->getPPS()->ctuToTileCol( ctuXPosInCtus );
    const unsigned  tileRowIdx      = slice->getPPS()->ctuToTileRow( ctuYPosInCtus );
    const unsigned  tileXPosInCtus  = slice->getPPS()->getTileColumnBd( tileColIdx );
    const unsigned  tileYPosInCtus  = slice->getPPS()->getTileRowBd( tileRowIdx );
    const unsigned  tileColWidth    = slice->getPPS()->getTileColumnWidth( tileColIdx );
    const unsigned  tileRowHeight   = slice->getPPS()->getTileRowHeight( tileRowIdx );
    const unsigned  tileIdx         = slice->getPPS()->getTileIdx( ctuXPosInCtus, ctuYPosInCtus);
    const unsigned  maxCUSize             = sps->getMaxCUWidth();
    Position pos( ctuXPosInCtus*maxCUSize, ctuYPosInCtus*maxCUSize) ;
    UnitArea ctuArea(cs.area.chromaFormat, Area( pos.x, pos.y, maxCUSize, maxCUSize ) );

    DTRACE_UPDATE( g_trace_ctx, std::make_pair( "ctu", ctuRsAddr ) );

    cabacReader.initBitstream( ppcSubstreams[subStrmId] );

    // set up CABAC contexts' state for this CTU
    if( ctuXPosInCtus == tileXPosInCtus && ctuYPosInCtus == tileYPosInCtus )
    {
      if( ctuIdx != 0 ) // if it is the first CTU, then the entropy coder has already been reset
      {
        cabacReader.initCtxModels( *slice );
        cs.resetPrevPLT(cs.prevPLT);
      }
      pic->m_prevQP[0] = pic->m_prevQP[1] = slice->getSliceQp();
    }
    else if( ctuXPosInCtus == tileXPosInCtus && wavefrontsEnabled )
    {
      // Synchronize cabac probabilities with top CTU if it's available and at the start of a line.
      if( ctuIdx != 0 ) // if it is the first CTU, then the entropy coder has already been reset
      {
        cabacReader.initCtxModels( *slice );
        cs.resetPrevPLT(cs.prevPLT);
      }
      if( cs.getCURestricted( pos.offset(0, -1), pos, slice->getIndependentSliceIdx(), tileIdx, CH_L ) )
      {
        // Top is available, so use it.
        cabacReader.getCtx() = m_entropyCodingSyncContextState;
      }
      pic->m_prevQP[0] = pic->m_prevQP[1] = slice->getSliceQp();
    }

    bool updateBcwCodingOrder = cs.slice->getSliceType() == B_SLICE && ctuIdx == 0;
    if(updateBcwCodingOrder)
    {
      resetBcwCodingOrder(true, cs);
    }

    if ((cs.slice->getSliceType() != I_SLICE || cs.sps->getIBCFlag()) && ctuXPosInCtus == tileXPosInCtus)
    {
      cs.motionLut.lut.resize(0);
      cs.motionLut.lutIbc.resize(0);
      cs.resetIBCBuffer = true;
    }

    if( !cs.slice->isIntra() )
    {
      pic->mctsInfo.init( &cs, getCtuAddr( ctuArea.lumaPos(), *( cs.pcv ) ) );
    }

    if( ctuRsAddr == debugCTU )
    {
      break;
    }
    cabacReader.coding_tree_unit( cs, ctuArea, pic->m_prevQP, ctuRsAddr );

    m_pcCuDecoder->decompressCtu( cs, ctuArea );

    if( ctuXPosInCtus == tileXPosInCtus && wavefrontsEnabled )
    {
      m_entropyCodingSyncContextState = cabacReader.getCtx();
    }


    if( ctuIdx == slice->getNumCtuInSlice()-1 )
    {
      unsigned binVal = cabacReader.terminating_bit();
      CHECK( !binVal, "Expecting a terminating bit" );
#if DECODER_CHECK_SUBSTREAM_AND_SLICE_TRAILING_BYTES
      cabacReader.remaining_bytes( false );
#endif
    }
    else if( ( ctuXPosInCtus + 1 == tileXPosInCtus + tileColWidth ) &&
             ( ctuYPosInCtus + 1 == tileYPosInCtus + tileRowHeight || wavefrontsEnabled ) )
    {
      // The sub-stream/stream should be terminated after this CTU.
      // (end of slice-segment, end of tile, end of wavefront-CTU-row)
      unsigned binVal = cabacReader.terminating_bit();
      CHECK( !binVal, "Expecting a terminating bit" );
#if DECODER_CHECK_SUBSTREAM_AND_SLICE_TRAILING_BYTES
      cabacReader.remaining_bytes( true );
#endif
      subStrmId++;
    }
  }

  // deallocate all created substreams, including internal buffers.
  for( auto substr: ppcSubstreams )
  {
    delete substr;
  }
  slice->stopProcessingTimer();
}

//! \}