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/** \file     UnitPartitioner.h

 *  \brief    Provides a class for partitioning management

 */

#include "UnitPartitioner.h"

#include "CodingStructure.h"

#include "Unit.h"

#include "Slice.h"

#include "UnitTools.h"

#include "Picture.h"

//! \ingroup CommonLib

//! \{

namespace vvenc {

PartLevel::PartLevel()

: split               ( CU_DONT_SPLIT )

, parts               (               )

, idx                 ( 0u            )

, checkdIfImplicit    ( false         )

, isImplicit          ( false         )

, implicitSplit       ( CU_DONT_SPLIT )

, firstSubPartSplit   ( CU_DONT_SPLIT )

, canQtSplit          ( true          )

, qgEnable            ( true          )

, qgChromaEnable      ( true          )

, modeType            ( MODE_TYPE_ALL )

{

}

void PartLevel::init()

{

  split               = CU_DONT_SPLIT;

  idx                 = 0u;

  checkdIfImplicit    = false;

  isImplicit          = false;

  implicitSplit       = CU_DONT_SPLIT;

  firstSubPartSplit   = CU_DONT_SPLIT;

  canQtSplit          = true;

  qgEnable            = true;

  qgChromaEnable      = true;

  modeType            = MODE_TYPE_ALL;

  numParts            = 0;

}

//////////////////////////////////////////////////////////////////////////

// Partitioner class

//////////////////////////////////////////////////////////////////////////

SplitSeries Partitioner::getSplitSeries() const

{

  SplitSeries splitSeries = 0;

  SplitSeries depth = 0;

  for( const auto &level : m_partStack )

  {

    if( level.split == CTU_LEVEL ) continue;

    else splitSeries += static_cast< SplitSeries >( level.split ) << ( depth * SPLIT_DMULT );

    depth++;

  }

  return splitSeries;

}

ModeTypeSeries Partitioner::getModeTypeSeries() const

{

  ModeTypeSeries modeTypeSeries = 0;

  int depth = 0;

  for( const auto &level : m_partStack )

  {

    if( level.split == CTU_LEVEL ) continue;

    else modeTypeSeries += static_cast<int>(level.modeType) << (depth * 3);

    depth++;

  }

  return modeTypeSeries;

}

bool Partitioner::isSepTree( const CodingStructure &cs )

{

  return treeType != TREE_D || CS::isDualITree( cs );

}

void Partitioner::setCUData( CodingUnit& cu )

{

  cu.depth       = currDepth;

  cu.btDepth     = currBtDepth;

  cu.mtDepth     = currMtDepth;

  cu.qtDepth     = currQtDepth;

  cu.splitSeries = getSplitSeries();

  cu.modeTypeSeries = getModeTypeSeries();

  cu.treeType    = treeType; 

  cu.modeType    = modeType; 

}

void Partitioner::copyState( const Partitioner& other )

{

  m_partStack = other.m_partStack;

  currBtDepth = other.currBtDepth;

  currQtDepth = other.currQtDepth;

  currDepth   = other.currDepth;

  currMtDepth = other.currMtDepth;

  currTrDepth = other.currTrDepth;

  currSubdiv  = other.currSubdiv;

  currQgPos   = other.currQgPos;

  currQgChromaPos = other.currQgChromaPos;

  currImplicitBtDepth

              = other.currImplicitBtDepth;

  chType      = other.chType;

#ifdef _DEBUG

  m_currArea  = other.m_currArea;

#endif

}

void Partitioner::setMaxMinDepth( unsigned& minDepth, unsigned& maxDepth, const CodingStructure& cs, int QtbttSpeedUp, bool MergeFlag) const

{

  unsigned          stdMinDepth = 0;

  unsigned          stdMaxDepth = cs.pcv->getMaxDepth( cs.slice->sliceType, chType );

  const Position    pos         = currArea().blocks[chType].pos();

  const unsigned    curSliceIdx = cs.slice->independentSliceIdx;

  const unsigned    curTileIdx  = cs.pps->getTileIdx( currArea().lumaPos() );

  const CodingUnit* cuLeft        = cs.getCURestricted( pos.offset( -1,                               0 ), pos, curSliceIdx, curTileIdx, chType, treeType );

  const CodingUnit* cuBelowLeft   = cs.getCURestricted( pos.offset( -1, currArea().blocks[chType].height), pos, curSliceIdx, curTileIdx, chType, treeType );

  const CodingUnit* cuAbove       = cs.getCURestricted( pos.offset(  0,                              -1 ), pos, curSliceIdx, curTileIdx, chType, treeType );

  const CodingUnit* cuAboveRight  = cs.getCURestricted( pos.offset( currArea().blocks[chType].width, -1 ), pos, curSliceIdx, curTileIdx, chType, treeType );

  minDepth = stdMaxDepth;

  maxDepth = stdMinDepth;

  if( cuLeft )

  {

    minDepth = std::min<unsigned>( minDepth, cuLeft->qtDepth );

    maxDepth = std::max<unsigned>( maxDepth, cuLeft->qtDepth );

  }

  else

  {

    minDepth = stdMinDepth;

    maxDepth = stdMaxDepth;

  }

  if( cuBelowLeft )

  {

    minDepth = std::min<unsigned>( minDepth, cuBelowLeft->qtDepth );

    maxDepth = std::max<unsigned>( maxDepth, cuBelowLeft->qtDepth );

  }

  else

  {

    minDepth = stdMinDepth;

    maxDepth = stdMaxDepth;

  }

  if( cuAbove )

  {

    minDepth = std::min<unsigned>( minDepth, cuAbove->qtDepth );

    maxDepth = std::max<unsigned>( maxDepth, cuAbove->qtDepth );

  }

  else

  {

    minDepth = stdMinDepth;

    maxDepth = stdMaxDepth;

  }

  if( cuAboveRight )

  {

    minDepth = std::min<unsigned>( minDepth, cuAboveRight->qtDepth );

    maxDepth = std::max<unsigned>( maxDepth, cuAboveRight->qtDepth );

  }

  else

  {

    minDepth = stdMinDepth;

    maxDepth = stdMaxDepth;

  }

  minDepth = ( minDepth >= 1 ? minDepth - 1 : 0 );

  maxDepth = std::min<unsigned>( stdMaxDepth, maxDepth + 1 );

  if((QtbttSpeedUp >> 2) && (cs.slice->TLayer > 0) && ((cs.area.Y().width >= 8) || (cs.area.Y().height >= 8)))

  {

    int minDepthCur = stdMaxDepth;

    int maxDepthCur = stdMinDepth;

    int amountN = 0;

    for (int n = 0; n < 3; n++)

    {

      const CodingUnit* cuNeigh = (n==0)?cs.getCURestricted(pos.offset(-1, -1), pos, curSliceIdx, curTileIdx, chType, treeType): (n==1)? cuAbove : cuLeft;

      if (cuNeigh)

      {

        amountN++;

        minDepthCur = std::min<unsigned>(minDepthCur, cuNeigh->qtDepth);

        maxDepthCur = std::max<unsigned>(maxDepthCur, cuNeigh->qtDepth);

      }

    }

    if (amountN)

    {

      minDepthCur = (minDepthCur >= 1 ? minDepthCur - 1 : 0);

      maxDepthCur = std::min<unsigned>(stdMaxDepth, maxDepthCur + 1);

      maxDepth = std::min<unsigned>(maxDepthCur, maxDepth);

      minDepth = std::max<unsigned>(minDepthCur, minDepth);

    }

  }

  if (!cs.slice->isIntra() && (QtbttSpeedUp & 3))

  {

    bool doMin_SCC = !(((QtbttSpeedUp & 3) == 2) && (cs.area.Y().width < cs.pcv->maxCUSize));

    bool LimitDepths = (QtbttSpeedUp & 2) ? (MergeFlag == 0) : (cs.area.Y().width >= cs.pcv->maxCUSize);

    if (LimitDepths && cuAbove && cuLeft && (cuLeft->qtDepth == cuAbove->qtDepth))

    {

      int minDepthCur = cuAbove->qtDepth;

      int maxDepthCur = cuAbove->qtDepth;

      minDepthCur = (minDepthCur > 0) ? (minDepthCur - 1) : 0;

      maxDepthCur = (maxDepthCur < stdMaxDepth) ? (maxDepthCur + 1) : maxDepthCur;

      maxDepth = std::min<unsigned>(maxDepthCur, maxDepth);

      minDepth = std::max<unsigned>(minDepthCur, minDepth);

    }

    else if (doMin_SCC && LimitDepths && cuAbove && cuLeft)

    {

      int minDepthCur = cuAbove->qtDepth;

      int maxDepthCur = cuAbove->qtDepth;

      minDepthCur = (minDepthCur > 0) ? (minDepthCur - 1) : 0;

      maxDepthCur = (maxDepthCur < stdMaxDepth) ? (maxDepthCur + 1) : maxDepthCur;

      if ((cuLeft->qtDepth > maxDepthCur) && ((cuLeft->qtDepth - 1) >= maxDepthCur))

      {

        minDepthCur += 1;

        maxDepthCur += 1;

      }

      else if ((cuLeft->qtDepth < minDepthCur) && ((cuLeft->qtDepth + 1) <= minDepthCur))

      {

        maxDepthCur -= 1;

        minDepthCur -= 1;

      }

      maxDepth = std::min<unsigned>(maxDepthCur, maxDepth);

      minDepth = std::max<unsigned>(minDepthCur, minDepth);

    }

    if ((QtbttSpeedUp & 2) && MergeFlag && (maxDepth == 4) && (cs.area.Y().width <= 16))

    {

      maxDepth = 3;

      minDepth = (minDepth == 3)? 2: minDepth;

    }

  }

}

void Partitioner::initCtu( const UnitArea& ctuArea, const ChannelType _chType, const Slice& slice )

{

#if _DEBUG

  m_currArea = ctuArea;

#endif

  currDepth   = 0;

  currTrDepth = 0;

  currBtDepth = 0;

  currMtDepth = 0;

  currQtDepth = 0;

  currSubdiv  = 0;

  currQgPos   = ctuArea.lumaPos();

  currQgChromaPos = ctuArea.chromaFormat != CHROMA_400 ? ctuArea.chromaPos() : Position();

  currImplicitBtDepth = 0;

  chType      = _chType;

  const PreCalcValues& pcv = *slice.pps->pcv;

  maxBTD      = pcv.getMaxMTTDepth( slice, chType );

  maxBtSize   = pcv.getMaxBtSize  ( slice, chType );

  minTSize    = pcv.getMinTSize   ( slice, chType );

  maxTtSize   = pcv.getMaxTtSize  ( slice, chType );

  minQtSize   = pcv.getMinQtSize  ( slice, chType );

  m_partBufIdx = 1;

  m_partStack.resize_noinit( 1 );

  m_partStack.back().init();

  m_partStack.back().split = CTU_LEVEL;

  m_partStack.back().parts = m_partBuf;

  m_partStack.back().parts[0] = ctuArea;

  m_partStack.back().numParts = 1;

  treeType = TREE_D;

  modeType = MODE_TYPE_ALL;

}

void Partitioner::splitCurrArea( const PartSplit split, const CodingStructure& cs )

{

  if ((split != TU_1D_HORZ_SPLIT) && (split != TU_1D_VERT_SPLIT))

  {

    CHECKD(!canSplit(split, cs), "Trying to apply a prohibited split!");

  }

  bool isImplicit = isSplitImplicit( split, cs );

  bool canQtSplit = canSplit( CU_QUAD_SPLIT, cs );

  bool qgEnable = currQgEnable();

  bool qgChromaEnable = currQgChromaEnable();

  const UnitArea& area = currArea();

  m_partStack.resize_noinit( m_partStack.size() + 1 );

  PartLevel& back = m_partStack.back();

  back.init();

  back.split = split;

  back.parts = &m_partBuf[m_partBufIdx];

  int numParts;

  CHECK( m_partBufIdx > partBufSize, "Partition buffer overflow" );

  switch( split )

  {

  case CU_QUAD_SPLIT:

    numParts = PartitionerImpl::getCUSubPartitions( back.parts, area, cs, split );

    back.modeType = modeType;

    break;

  case CU_HORZ_SPLIT:

  case CU_VERT_SPLIT:

    numParts = PartitionerImpl::getCUSubPartitions( back.parts, area, cs, split );

    back.modeType = modeType;

    break;

  case CU_TRIH_SPLIT:

  case CU_TRIV_SPLIT:

    numParts = PartitionerImpl::getCUSubPartitions( back.parts, area, cs, split );

    back.modeType = modeType;

    break;

  case TU_MAX_TR_SPLIT:

    numParts = PartitionerImpl::getMaxTuTiling( back.parts, area, cs );

    break;

  case SBT_VER_HALF_POS0_SPLIT:

  case SBT_VER_HALF_POS1_SPLIT:

  case SBT_HOR_HALF_POS0_SPLIT:

  case SBT_HOR_HALF_POS1_SPLIT:

  case SBT_VER_QUAD_POS0_SPLIT:

  case SBT_VER_QUAD_POS1_SPLIT:

  case SBT_HOR_QUAD_POS0_SPLIT:

  case SBT_HOR_QUAD_POS1_SPLIT:

    numParts = PartitionerImpl::getSbtTuTiling( back.parts, area, cs, split );

    break;

  case TU_1D_HORZ_SPLIT:

  case TU_1D_VERT_SPLIT:

  {

    numParts = PartitionerImpl::getTUIntraSubPartitions(back.parts, area, cs, split, TREE_D);

    break;

  }

  default:

    THROW( "Unknown split mode" );

    break;

  }

  back.numParts = numParts;

  m_partBufIdx += numParts;

  CHECK( m_partBufIdx > partBufSize, "Partition buffer overflow" );

  currDepth++;

  currSubdiv++;

#if _DEBUG

  m_currArea = m_partStack.back().parts[0];

#endif

  if ((split == TU_MAX_TR_SPLIT) || (split == TU_1D_HORZ_SPLIT) || (split == TU_1D_VERT_SPLIT))

  {

    currTrDepth++;

  }

  else if( split >= SBT_VER_HALF_POS0_SPLIT && split <= SBT_HOR_QUAD_POS1_SPLIT )

  {

    currTrDepth++;

  }

  else

  {

    currTrDepth = 0;

  }

  if( split == CU_HORZ_SPLIT || split == CU_VERT_SPLIT || split == CU_TRIH_SPLIT || split == CU_TRIV_SPLIT )

  {

    currBtDepth++;

    if( isImplicit ) currImplicitBtDepth++;

    currMtDepth++;

    if( split == CU_TRIH_SPLIT || split == CU_TRIV_SPLIT )

    {

      // first and last part of triple split are equivalent to double bt split

      currBtDepth++;

      currSubdiv++;

    }

    m_partStack.back().canQtSplit = canQtSplit;

  }

  else if( split == CU_QUAD_SPLIT )

  {

    CHECK( currBtDepth > 0, "Cannot split a non-square area other than with a binary split" );

    CHECK( currMtDepth > 0, "Cannot split a non-square area other than with a binary split" );

    currMtDepth = 0;

    currBtDepth = 0;

    currQtDepth++;

    currSubdiv++;

  }

  qgEnable       &= (currSubdiv <= (cs.slice->isIntra() ? cs.slice->picHeader->cuQpDeltaSubdivIntra : cs.slice->picHeader->cuQpDeltaSubdivInter ));

  qgChromaEnable &= (currSubdiv <= (cs.slice->isIntra() ? cs.slice->picHeader->cuChromaQpOffsetSubdivIntra : cs.slice->picHeader->cuChromaQpOffsetSubdivInter ));

  m_partStack.back().qgEnable       = qgEnable;

  m_partStack.back().qgChromaEnable = qgChromaEnable;

  if (qgEnable)

    currQgPos = currArea().lumaPos();

  if (qgChromaEnable)

    currQgChromaPos = currArea().chromaPos();

}

void Partitioner::canSplit( const CodingStructure &cs, bool& canNo, bool& canQt, bool& canBh, bool& canBv, bool& canTh, bool& canTv )

{

  const PartSplit implicitSplit = m_partStack.back().checkdIfImplicit ? m_partStack.back().implicitSplit : getImplicitSplit( cs );

  canNo = canQt = canBh = canTh = canBv = canTv = true;

  bool canBtt = currMtDepth < (maxBTD + currImplicitBtDepth);

  // the minimal and maximal sizes are given in luma samples

  const CompArea&  area  = currArea().Y();

  const CompArea  *areaC = (chType == CH_C) ? &(currArea().Cb()) : nullptr;

        PartLevel& level = m_partStack.back();

  const PartSplit lastSplit = level.split;

  const PartSplit parlSplit = lastSplit == CU_TRIH_SPLIT ? CU_HORZ_SPLIT : CU_VERT_SPLIT;

  // don't allow QT-splitting below a BT split

  if( lastSplit != CTU_LEVEL && lastSplit != CU_QUAD_SPLIT ) canQt = false;

  // minQtSize is in luma samples unit

  const unsigned minQTThreshold = minQtSize >> ((area.chromaFormat == CHROMA_400) ? 0 : ((int) getChannelTypeScaleX(CH_C, area.chromaFormat) - (int) getChannelTypeScaleY(CH_C, area.chromaFormat)));

  if( area.width <= minQTThreshold )                         canQt = false;

  if( areaC && areaC->width <= MIN_DUALTREE_CHROMA_WIDTH ) canQt = false;

  if( treeType == TREE_C )

  {

    canQt = canBh = canTh = canBv = canTv = false;

    return;

  }

  if( implicitSplit != CU_DONT_SPLIT )

  {

    canNo = canTh = canTv = false;

    canBh = implicitSplit == CU_HORZ_SPLIT;

    canBv = implicitSplit == CU_VERT_SPLIT;

    if (areaC && areaC->width == 4) canBv = false;

    if( !canBh && !canBv && !canQt ) canQt = true;

    return;

  }

  if( ( lastSplit == CU_TRIH_SPLIT || lastSplit == CU_TRIV_SPLIT ) && currPartIdx() == 1 )

  {

    canBh = parlSplit != CU_HORZ_SPLIT;

    canBv = parlSplit != CU_VERT_SPLIT;

  }

  if( canBtt && ( area.width <= minTSize && area.height <= minTSize ) )

  {

    canBtt = false;

  }

  if( canBtt && ( area.width > maxBtSize || area.height > maxBtSize )

      && ( ( area.width > maxTtSize || area.height > maxTtSize ) ) )

  {

    canBtt = false;

  }

  if( !canBtt )

  {

    canBh = canTh = canBv = canTv = false;

    return;

  }

  if( area.width > maxBtSize || area.height > maxBtSize )

  {

    canBh = canBv = false;

  }

  // specific check for BT splits

  if( area.height <= minTSize )                            canBh = false;

  if( area.width > MAX_TB_SIZEY && area.height <= MAX_TB_SIZEY ) canBh = false;

  if( areaC && areaC->width * areaC->height <= MIN_DUALTREE_CHROMA_SIZE )     canBh = false;

  if( area.width <= minTSize )                              canBv = false;

  if( area.width <= MAX_TB_SIZEY && area.height > MAX_TB_SIZEY ) canBv = false;

  if (areaC && (areaC->width * areaC->height <= MIN_DUALTREE_CHROMA_SIZE || areaC->width == 4))     canBv = false;

  if( modeType == MODE_TYPE_INTER && area.width * area.height == 32 )  canBv = canBh = false;

  if( area.height <= 2 * minTSize || area.height > maxTtSize || area.width > maxTtSize )

                                                                                       canTh = false;

  if( area.width > MAX_TB_SIZEY || area.height > MAX_TB_SIZEY )  canTh = false;

  if( areaC && areaC->width * areaC->height <= MIN_DUALTREE_CHROMA_SIZE*2 )     canTh = false;

  if( area.width <= 2 * minTSize || area.width > maxTtSize || area.height > maxTtSize )

                                                                                       canTv = false;

  if( area.width > MAX_TB_SIZEY || area.height > MAX_TB_SIZEY )  canTv = false;

  if (areaC && (areaC->width * areaC->height <= MIN_DUALTREE_CHROMA_SIZE * 2 || areaC->width == 8))     canTv = false;

  if( modeType == MODE_TYPE_INTER && area.width * area.height == 64 )  canTv = canTh = false;

}

bool Partitioner::canSplit( const PartSplit split, const CodingStructure &cs )

{

  const CompArea area       = currArea().Y();

  const unsigned maxTrSize  = cs.sps->getMaxTbSize();

  bool canNo, canQt, canBh, canTh, canBv, canTv;

  canSplit( cs, canNo, canQt, canBh, canBv, canTh, canTv );

  switch( split )

  {

  case CTU_LEVEL:

    THROW( "Checking if top level split is possible" );

    return true;

    break;

  case TU_MAX_TR_SPLIT:

    return area.width > maxTrSize || area.height > maxTrSize;

    break;

  case SBT_VER_HALF_POS0_SPLIT:

  case SBT_VER_HALF_POS1_SPLIT:

  case SBT_HOR_HALF_POS0_SPLIT:

  case SBT_HOR_HALF_POS1_SPLIT:

  case SBT_VER_QUAD_POS0_SPLIT:

  case SBT_VER_QUAD_POS1_SPLIT:

  case SBT_HOR_QUAD_POS0_SPLIT:

  case SBT_HOR_QUAD_POS1_SPLIT:

    return currTrDepth == 0;

    break;

  case CU_QUAD_SPLIT:

    return canQt;

  case CU_DONT_SPLIT:

    return canNo;

  case CU_HORZ_SPLIT:

    return canBh;

  case CU_VERT_SPLIT:

    return canBv;

  case CU_TRIH_SPLIT:

    return canTh;

  case CU_TRIV_SPLIT:

    return canTv;

  case CU_MT_SPLIT:

    return ( canBh || canTh || canBv || canTv );

  case CU_BT_SPLIT:

    return ( canBh || canBv );

  break;

  default:

    THROW( "Unknown split mode" );

    return false;

    break;

  }

  return true;

}

bool Partitioner::canSplitISP(const PartSplit split, const CodingStructure& cs, CodingUnit& cu)

{

  // const PartSplit implicitSplit = getImplicitSplit(cs);

  const UnitArea& area = currArea();

  switch (split)

  {

  case TU_1D_HORZ_SPLIT:

  {

    return area.lheight() == cu.lheight();

  }

  case TU_1D_VERT_SPLIT:

  {

    return area.lwidth() == cu.lwidth();

  }

  case TU_MAX_TR_SPLIT:

  {

    // this split is performed implicitly with the other splits

    return false;

  }

  default: THROW("Unknown 1-D split mode"); break;

  }

}

bool Partitioner::isSplitImplicit( const PartSplit split, const CodingStructure &cs )

{

  return split == getImplicitSplit( cs );

}

PartSplit Partitioner::getImplicitSplit( const CodingStructure &cs )

{

  if( m_partStack.back().checkdIfImplicit )

  {

    return m_partStack.back().implicitSplit;

  }

  PartSplit split = CU_DONT_SPLIT;

  if( split == CU_DONT_SPLIT )

  {

    const bool isBlInPic = cs.picture->Y().contains( currArea().Y().bottomLeft() );

    const bool isTrInPic = cs.picture->Y().contains( currArea().Y().topRight() );

    const CompArea& area      = currArea().Y();

    const bool isBtAllowed    = area.width <= maxBtSize && area.height <= maxBtSize && currMtDepth < (maxBTD + currImplicitBtDepth);

    // minQtSize is in luma samples unit

    const unsigned minQTThreshold = minQtSize >> ((area.chromaFormat == CHROMA_400) ? 0 : ((int) getChannelTypeScaleX(CH_C, area.chromaFormat) - (int) getChannelTypeScaleY(CH_C, area.chromaFormat)));

    const bool isQtAllowed    = area.width > minQTThreshold && currBtDepth == 0;

    if( !isBlInPic && !isTrInPic && isQtAllowed )

    {

      split = CU_QUAD_SPLIT;

    }

    else if( !isBlInPic && isBtAllowed && area.width <= MAX_TB_SIZEY )

    {

      split = CU_HORZ_SPLIT;

    }

    else if( !isTrInPic && isBtAllowed && area.height <= MAX_TB_SIZEY )

    {

      split = CU_VERT_SPLIT;

    }

    else if( !isBlInPic || !isTrInPic )

    {

      split = CU_QUAD_SPLIT;

    }

    if (CS::isDualITree(cs) && (currArea().Y().width > 64 || currArea().Y().height > 64))

    {

      split = CU_QUAD_SPLIT;

    }

    if( (!isBlInPic || !isTrInPic) && split == CU_DONT_SPLIT )

    {

      split = CU_QUAD_SPLIT;

    }

  }

  m_partStack.back().checkdIfImplicit = true;

  m_partStack.back().isImplicit = split != CU_DONT_SPLIT;

  m_partStack.back().implicitSplit = split;

  return split;

}

void Partitioner::exitCurrSplit()

{

  const PartSplit currSplit = m_partStack.back().split;

  const int       currIndex = m_partStack.back().idx;

  const int       numParts  = m_partStack.back().numParts;

  m_partStack.pop_back();

  m_partBufIdx -= numParts;

  CHECK( currDepth == 0, "depth is '0', although a split was performed" );

  currDepth--;

  currSubdiv--;

  if( currQgEnable() )

    currQgPos = currArea().lumaPos();

  if( currArea().chromaFormat != CHROMA_400 && currQgChromaEnable() )

    currQgChromaPos = currArea().chromaPos();

#if _DEBUG

  m_currArea = m_partStack.back().parts[m_partStack.back().idx];

#endif

  if( currSplit == CU_HORZ_SPLIT || currSplit == CU_VERT_SPLIT || currSplit == CU_TRIH_SPLIT || currSplit == CU_TRIV_SPLIT )

  {

    CHECK( !m_partStack.back().checkdIfImplicit, "Didn't check if the current split is implicit" );

    CHECK( currBtDepth == 0, "BT depth is '0', athough a BT split was performed" );

    CHECK( currMtDepth == 0, "MT depth is '0', athough a BT split was performed" );

    currMtDepth--;

    if( m_partStack.back().isImplicit ) currImplicitBtDepth--;

    currBtDepth--;

    if( ( currSplit == CU_TRIH_SPLIT || currSplit == CU_TRIV_SPLIT ) && currIndex != 1 )

    {

      CHECK( currBtDepth == 0, "BT depth is '0', athough a TT split was performed" );

      currBtDepth--;

      currSubdiv--;

    }

  }

  else if( currSplit == TU_MAX_TR_SPLIT )

  {

    CHECK( currTrDepth == 0, "TR depth is '0', although a TU split was performed" );

    currTrDepth--;

  }

  else if( currSplit >= SBT_VER_HALF_POS0_SPLIT && currSplit <= SBT_HOR_QUAD_POS1_SPLIT )

  {

    CHECK( currTrDepth == 0, "TR depth is '0', although a TU split was performed" );

    currTrDepth--;

  }

  else if ((currSplit == TU_1D_HORZ_SPLIT) || (currSplit == TU_1D_VERT_SPLIT))

  {

    CHECK(currTrDepth == 0, "TR depth is '0', although a TU split was performed");

    currTrDepth--;

  }

  else

  {

    CHECK( currTrDepth > 0, "RQT found with QTBT partitioner" );

    CHECK( currQtDepth == 0, "QT depth is '0', although a QT split was performed" );

    currQtDepth--;

    currSubdiv--;

  }

}

bool Partitioner::nextPart( const CodingStructure &cs, bool autoPop /*= false*/ )

{

  const Position& prevPos = currArea().blocks[chType].pos();

  unsigned currIdx = ++m_partStack.back().idx;

  m_partStack.back().checkdIfImplicit = false;

  m_partStack.back().isImplicit = false;

  if( currIdx == 1 )

  {

    const CodingUnit* prevCU = cs.getCU( prevPos, chType, treeType );

    m_partStack.back().firstSubPartSplit = prevCU ? CU::getSplitAtDepth( *prevCU, currDepth ) : CU_DONT_SPLIT;

  }

  if( currIdx < m_partStack.back().numParts )

  {

    if( m_partStack.back().split == CU_TRIH_SPLIT || m_partStack.back().split == CU_TRIV_SPLIT )

    {

      // adapt the current bt depth

      if( currIdx == 1 ) currBtDepth--;

      else               currBtDepth++;

      if( currIdx == 1 ) currSubdiv--;

      else               currSubdiv++;

    }

  if( currQgEnable() )

    currQgPos = currArea().lumaPos();

  if( currQgChromaEnable() )

    currQgChromaPos = currArea().chromaPos();

#if _DEBUG

    m_currArea = m_partStack.back().parts[currIdx];

#endif

    return true;

  }

  else

  {

    if( autoPop ) exitCurrSplit();

    return false;

  }

}

bool Partitioner::hasNextPart()

{

  return ( ( m_partStack.back().idx + 1 ) < m_partStack.back().numParts );

}

//////////////////////////////////////////////////////////////////////////

// Partitioner methods describing the actual partitioning logic

//////////////////////////////////////////////////////////////////////////

int PartitionerImpl::getCUSubPartitions( Partitioning& dst, const UnitArea &cuArea, const CodingStructure &cs, const PartSplit _splitType )

{

  const PartSplit splitType = _splitType;

  if( splitType == CU_QUAD_SPLIT )

  {

    Partitioning& sub = dst;

    for( uint32_t i = 0; i < 4; i++ )

    {

      sub[i] = cuArea;

      for( auto &blk : sub[i].blocks )

      {

        blk.height >>= 1;

        blk.width  >>= 1;

        if( i >= 2 ) blk.y += blk.height;

        if( i &  1 ) blk.x += blk.width;

      }

    }

    return 4;

  }

  else if( splitType == CU_HORZ_SPLIT )

  {

    Partitioning& sub = dst;

    for (uint32_t i = 0; i < 2; i++)

    {

      sub[i] = cuArea;

      for (auto &blk : sub[i].blocks)

      {

        blk.height >>= 1;

        if (i == 1) blk.y += blk.height;

      }

    }

    return 2;

  }

  else if( splitType == CU_VERT_SPLIT )

  {

    Partitioning& sub = dst;

    for( uint32_t i = 0; i < 2; i++ )

    {

      sub[i] = cuArea;

      for( auto &blk : sub[i].blocks )

      {

        blk.width >>= 1;

        if( i == 1 ) blk.x += blk.width;

      }

    }

    return 2;

  }

  else if( splitType == CU_TRIH_SPLIT )

  {

    Partitioning& sub = dst;

    for( int i = 0; i < 3; i++ )

    {

      sub[i] = cuArea;

      for( auto &blk : sub[i].blocks )

      {

        blk.height >>= 1;

        if( ( i + 1 ) & 1 ) blk.height >>= 1;

        if( i == 1 )        blk.y       +=     blk.height / 2;

        if( i == 2 )        blk.y       += 3 * blk.height;

      }

    }

    return 3;

  }

  else if( splitType == CU_TRIV_SPLIT )

  {

    Partitioning& sub = dst;

    for( int i = 0; i < 3; i++ )

    {

      sub[i] = cuArea;

      for( auto &blk : sub[i].blocks )

      {

        blk.width >>= 1;

        if( ( i + 1 ) & 1 ) blk.width >>= 1;

        if( i == 1 )        blk.x      +=     blk.width / 2;

        if( i == 2 )        blk.x      += 3 * blk.width;

      }

    }

    return 3;

  }

  else

  {

    THROW( "Unknown CU sub-partitioning" );

  }

}

int PartitionerImpl::getTUIntraSubPartitions( Partitioning& sub, const UnitArea &tuArea, const CodingStructure &cs, const PartSplit splitType, const TreeType treeType )

{

  uint32_t nPartitions;

  uint32_t splitDimensionSize = CU::getISPSplitDim( tuArea.lumaSize().width, tuArea.lumaSize().height, splitType );

  bool isDualTree = CS::isDualITree( cs ) || treeType != TREE_D;

  if( splitType == TU_1D_HORZ_SPLIT )

  {

    nPartitions = tuArea.lumaSize().height >> Log2(splitDimensionSize);

    for( uint32_t i = 0; i < nPartitions; i++ )

    {

      sub[i] = tuArea;

      CompArea& blkY = sub[i].blocks[COMP_Y];

      blkY.height = splitDimensionSize;

      blkY.y = i > 0 ? sub[i - 1].blocks[COMP_Y].y + splitDimensionSize : blkY.y;

      CHECK( sub[i].lumaSize().height < 1, "the cs split causes the block to be smaller than the minimal TU size" );

    }

  }

  else if( splitType == TU_1D_VERT_SPLIT )

  {

    nPartitions = tuArea.lumaSize().width >> Log2(splitDimensionSize);

    for( uint32_t i = 0; i < nPartitions; i++ )

    {

      sub[i] = tuArea;

      CompArea& blkY = sub[i].blocks[COMP_Y];

      blkY.width = splitDimensionSize;

      blkY.x = i > 0 ? sub[i - 1].blocks[COMP_Y].x + splitDimensionSize : blkY.x;

      CHECK( sub[i].lumaSize().width < 1, "the split causes the block to be smaller than the minimal TU size" );

    }

  }

  else

  {

    THROW( "Unknown TU sub-partitioning" );

  }

  //we only partition luma, so there is going to be only one chroma tu at the end (unless it is dual tree, in which case there won't be any chroma components)

  uint32_t partitionsWithoutChroma = (cs.area.chromaFormat == CHROMA_400) ? 0 : (isDualTree ? nPartitions : nPartitions - 1);

  for( uint32_t i = 0; i < partitionsWithoutChroma; i++ )

  {

    CompArea& blkCb = sub[i].blocks[COMP_Cb];

    CompArea& blkCr = sub[i].blocks[COMP_Cr];

    blkCb = CompArea();

    blkCr = CompArea();

  }

  return nPartitions;

}

static const int g_rsScanToZ_w4[16] =

{

   0,  1,  4,  5, // wouldn't work for 128x32 blocks, but those are forbidden bcs of VPDU constraints

   2,  3,  6,  7, // correct ordering for 128x64 (TU32)

   8,  9, 12, 13,

  10, 11, 14, 15, // correct ordering for 128x128 (TU32)

};

static const int g_rsScanToZ_w2[8] =

{

   0,  1, // correct ordering for 64x32 (TU32) and 128x64 (TU64)

   2,  3, // correct ordering for 64x64 (TU32) and 128x128 (TU64)

   4,  5,

   6,  7, // correct ordering for 32x64 (TU32) and 64x128 (TU64)

};

static const int g_rsScanToZ_w1[4] =

{

   0, // no tiling, never used

   1, // correct ordering for 64x32 (TU32) and 128x64 (TU64)

   2,

   3, // correct ordering for 128x32 (TU32)

};

static const int* g_rsScanToZ[3] = { g_rsScanToZ_w1, g_rsScanToZ_w2, g_rsScanToZ_w4 };

int PartitionerImpl::getMaxTuTiling( Partitioning& dst, const UnitArea& cuArea, const CodingStructure& cs )

{

  const Size area = cuArea.lumaSize();

  const int maxTrSize = cs.sps->getMaxTbSize();

  const int numTilesH = std::max<int>( 1, area.width / maxTrSize );

  const int numTilesV = std::max<int>( 1, area.height / maxTrSize );

  const int numTiles  = numTilesH * numTilesV;

  const int numLog2H  = Log2( numTilesH );

  const int* rsScanToZ = g_rsScanToZ[numLog2H];

  Partitioning& ret = dst;

  for( int i = 0; i < numTiles; i++ )

  {

    ret[i] = cuArea;

    const int zid = rsScanToZ[i];

    const int y = zid >> numLog2H;