/* The copyright in this software is being made available under the BSD
 * License, included below. This software may be subject to other third party
 * and contributor rights, including patent rights, and no such rights are
 * granted under this license.
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 * Copyright (c) 2010-2016, ITU/ISO/IEC
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
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 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
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 *    be used to endorse or promote products derived from this software without
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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/**
 * \file
 * \brief Implementation of TComInterpolationFilter class
 */

// ====================================================================================================================
// Includes
// ====================================================================================================================

#include "TComRom.h"
#include "TComInterpolationFilter.h"
#include <assert.h>

#include "TComChromaFormat.h"


//! \ingroup TLibCommon
//! \{

// ====================================================================================================================
// Tables
// ====================================================================================================================

const TFilterCoeff TComInterpolationFilter::m_lumaFilter[LUMA_INTERPOLATION_FILTER_SUB_SAMPLE_POSITIONS][NTAPS_LUMA] =
{
  {  0, 0,   0, 64,  0,   0, 0,  0 },
  { -1, 4, -10, 58, 17,  -5, 1,  0 },
  { -1, 4, -11, 40, 40, -11, 4, -1 },
  {  0, 1,  -5, 17, 58, -10, 4, -1 }
};

const TFilterCoeff TComInterpolationFilter::m_chromaFilter[CHROMA_INTERPOLATION_FILTER_SUB_SAMPLE_POSITIONS][NTAPS_CHROMA] =
{
  {  0, 64,  0,  0 },
  { -2, 58, 10, -2 },
  { -4, 54, 16, -2 },
  { -6, 46, 28, -4 },
  { -4, 36, 36, -4 },
  { -4, 28, 46, -6 },
  { -2, 16, 54, -4 },
  { -2, 10, 58, -2 }
};

// ====================================================================================================================
// Private member functions
// ====================================================================================================================

/**
 * \brief Apply unit FIR filter to a block of samples
 *
 * \param bitDepth   bitDepth of samples
 * \param src        Pointer to source samples
 * \param srcStride  Stride of source samples
 * \param dst        Pointer to destination samples
 * \param dstStride  Stride of destination samples
 * \param width      Width of block
 * \param height     Height of block
 * \param isFirst    Flag indicating whether it is the first filtering operation
 * \param isLast     Flag indicating whether it is the last filtering operation
 */
Void TComInterpolationFilter::filterCopy(Int bitDepth, const Pel *src, Int srcStride, Pel *dst, Int dstStride, Int width, Int height, Bool isFirst, Bool isLast)
{
  Int row, col;

  if ( isFirst == isLast )
  {
    for (row = 0; row < height; row++)
    {
      for (col = 0; col < width; col++)
      {
        dst[col] = src[col];
      }

      src += srcStride;
      dst += dstStride;
    }
  }
  else if ( isFirst )
  {
    const Int shift = std::max<Int>(2, (IF_INTERNAL_PREC - bitDepth));

    for (row = 0; row < height; row++)
    {
      for (col = 0; col < width; col++)
      {
        Pel val = leftShift_round(src[col], shift);
        dst[col] = val - (Pel)IF_INTERNAL_OFFS;
      }

      src += srcStride;
      dst += dstStride;
    }
  }
  else
  {
    const Int shift = std::max<Int>(2, (IF_INTERNAL_PREC - bitDepth));

    Pel maxVal = (1 << bitDepth) - 1;
    Pel minVal = 0;
    for (row = 0; row < height; row++)
    {
      for (col = 0; col < width; col++)
      {
        Pel val = src[ col ];
        val = rightShift_round((val + IF_INTERNAL_OFFS), shift);
        if (val < minVal)
        {
          val = minVal;
        }
        if (val > maxVal)
        {
          val = maxVal;
        }
        dst[col] = val;
      }

      src += srcStride;
      dst += dstStride;
    }
  }
}

/**
 * \brief Apply FIR filter to a block of samples
 *
 * \tparam N          Number of taps
 * \tparam isVertical Flag indicating filtering along vertical direction
 * \tparam isFirst    Flag indicating whether it is the first filtering operation
 * \tparam isLast     Flag indicating whether it is the last filtering operation
 * \param  bitDepth   Bit depth of samples
 * \param  src        Pointer to source samples
 * \param  srcStride  Stride of source samples
 * \param  dst        Pointer to destination samples
 * \param  dstStride  Stride of destination samples
 * \param  width      Width of block
 * \param  height     Height of block
 * \param  coeff      Pointer to filter taps
 */
template<Int N, Bool isVertical, Bool isFirst, Bool isLast>
Void TComInterpolationFilter::filter(Int bitDepth, Pel const *src, Int srcStride, Pel *dst, Int dstStride, Int width, Int height, TFilterCoeff const *coeff)
{
  Int row, col;

  Pel c[8];
  c[0] = coeff[0];
  c[1] = coeff[1];
  if ( N >= 4 )
  {
    c[2] = coeff[2];
    c[3] = coeff[3];
  }
  if ( N >= 6 )
  {
    c[4] = coeff[4];
    c[5] = coeff[5];
  }
  if ( N == 8 )
  {
    c[6] = coeff[6];
    c[7] = coeff[7];
  }

  Int cStride = ( isVertical ) ? srcStride : 1;
  src -= ( N/2 - 1 ) * cStride;

  Int offset;
  Pel maxVal;
  Int headRoom = std::max<Int>(2, (IF_INTERNAL_PREC - bitDepth));
  Int shift    = IF_FILTER_PREC;
  // with the current settings (IF_INTERNAL_PREC = 14 and IF_FILTER_PREC = 6), though headroom can be
  // negative for bit depths greater than 14, shift will remain non-negative for bit depths of 8->20
  assert(shift >= 0);

  if ( isLast )
  {
    shift += (isFirst) ? 0 : headRoom;
    offset = 1 << (shift - 1);
    offset += (isFirst) ? 0 : IF_INTERNAL_OFFS << IF_FILTER_PREC;
    maxVal = (1 << bitDepth) - 1;
  }
  else
  {
    shift -= (isFirst) ? headRoom : 0;
    offset = (isFirst) ? -IF_INTERNAL_OFFS << shift : 0;
    maxVal = 0;
  }

  for (row = 0; row < height; row++)
  {
    for (col = 0; col < width; col++)
    {
      Int sum;

      sum  = src[ col + 0 * cStride] * c[0];
      sum += src[ col + 1 * cStride] * c[1];
      if ( N >= 4 )
      {
        sum += src[ col + 2 * cStride] * c[2];
        sum += src[ col + 3 * cStride] * c[3];
      }
      if ( N >= 6 )
      {
        sum += src[ col + 4 * cStride] * c[4];
        sum += src[ col + 5 * cStride] * c[5];
      }
      if ( N == 8 )
      {
        sum += src[ col + 6 * cStride] * c[6];
        sum += src[ col + 7 * cStride] * c[7];
      }

      Pel val = ( sum + offset ) >> shift;
      if ( isLast )
      {
        val = ( val < 0 ) ? 0 : val;
        val = ( val > maxVal ) ? maxVal : val;
      }
      dst[col] = val;
    }

    src += srcStride;
    dst += dstStride;
  }
}

/**
 * \brief Filter a block of samples (horizontal)
 *
 * \tparam N          Number of taps
 * \param  bitDepth   Bit depth of samples
 * \param  src        Pointer to source samples
 * \param  srcStride  Stride of source samples
 * \param  dst        Pointer to destination samples
 * \param  dstStride  Stride of destination samples
 * \param  width      Width of block
 * \param  height     Height of block
 * \param  isLast     Flag indicating whether it is the last filtering operation
 * \param  coeff      Pointer to filter taps
 */
template<Int N>
Void TComInterpolationFilter::filterHor(Int bitDepth, Pel *src, Int srcStride, Pel *dst, Int dstStride, Int width, Int height, Bool isLast, TFilterCoeff const *coeff)
{
  if ( isLast )
  {
    filter<N, false, true, true>(bitDepth, src, srcStride, dst, dstStride, width, height, coeff);
  }
  else
  {
    filter<N, false, true, false>(bitDepth, src, srcStride, dst, dstStride, width, height, coeff);
  }
}

/**
 * \brief Filter a block of samples (vertical)
 *
 * \tparam N          Number of taps
 * \param  bitDepth   Bit depth
 * \param  src        Pointer to source samples
 * \param  srcStride  Stride of source samples
 * \param  dst        Pointer to destination samples
 * \param  dstStride  Stride of destination samples
 * \param  width      Width of block
 * \param  height     Height of block
 * \param  isFirst    Flag indicating whether it is the first filtering operation
 * \param  isLast     Flag indicating whether it is the last filtering operation
 * \param  coeff      Pointer to filter taps
 */
template<Int N>
Void TComInterpolationFilter::filterVer(Int bitDepth, Pel *src, Int srcStride, Pel *dst, Int dstStride, Int width, Int height, Bool isFirst, Bool isLast, TFilterCoeff const *coeff)
{
  if ( isFirst && isLast )
  {
    filter<N, true, true, true>(bitDepth, src, srcStride, dst, dstStride, width, height, coeff);
  }
  else if ( isFirst && !isLast )
  {
    filter<N, true, true, false>(bitDepth, src, srcStride, dst, dstStride, width, height, coeff);
  }
  else if ( !isFirst && isLast )
  {
    filter<N, true, false, true>(bitDepth, src, srcStride, dst, dstStride, width, height, coeff);
  }
  else
  {
    filter<N, true, false, false>(bitDepth, src, srcStride, dst, dstStride, width, height, coeff);
  }
}

// ====================================================================================================================
// Public member functions
// ====================================================================================================================

/**
 * \brief Filter a block of Luma/Chroma samples (horizontal)
 *
 * \param  compID     Chroma component ID
 * \param  src        Pointer to source samples
 * \param  srcStride  Stride of source samples
 * \param  dst        Pointer to destination samples
 * \param  dstStride  Stride of destination samples
 * \param  width      Width of block
 * \param  height     Height of block
 * \param  frac       Fractional sample offset
 * \param  isLast     Flag indicating whether it is the last filtering operation
 * \param  fmt        Chroma format
 * \param  bitDepth   Bit depth
 */
Void TComInterpolationFilter::filterHor(const ComponentID compID, Pel *src, Int srcStride, Pel *dst, Int dstStride, Int width, Int height, Int frac, Bool isLast, const ChromaFormat fmt, const Int bitDepth )
{
  if ( frac == 0 )
  {
    filterCopy(bitDepth, src, srcStride, dst, dstStride, width, height, true, isLast );
  }
  else if (isLuma(compID))
  {
    assert(frac >= 0 && frac < LUMA_INTERPOLATION_FILTER_SUB_SAMPLE_POSITIONS);
    filterHor<NTAPS_LUMA>(bitDepth, src, srcStride, dst, dstStride, width, height, isLast, m_lumaFilter[frac]);
  }
  else
  {
    const UInt csx = getComponentScaleX(compID, fmt);
    assert(frac >=0 && csx<2 && (frac<<(1-csx)) < CHROMA_INTERPOLATION_FILTER_SUB_SAMPLE_POSITIONS);
    filterHor<NTAPS_CHROMA>(bitDepth, src, srcStride, dst, dstStride, width, height, isLast, m_chromaFilter[frac<<(1-csx)]);
  }
}


/**
 * \brief Filter a block of Luma/Chroma samples (vertical)
 *
 * \param  compID     Colour component ID
 * \param  src        Pointer to source samples
 * \param  srcStride  Stride of source samples
 * \param  dst        Pointer to destination samples
 * \param  dstStride  Stride of destination samples
 * \param  width      Width of block
 * \param  height     Height of block
 * \param  frac       Fractional sample offset
 * \param  isFirst    Flag indicating whether it is the first filtering operation
 * \param  isLast     Flag indicating whether it is the last filtering operation
 * \param  fmt        Chroma format
 * \param  bitDepth   Bit depth
 */
Void TComInterpolationFilter::filterVer(const ComponentID compID, Pel *src, Int srcStride, Pel *dst, Int dstStride, Int width, Int height, Int frac, Bool isFirst, Bool isLast, const ChromaFormat fmt, const Int bitDepth )
{
  if ( frac == 0 )
  {
    filterCopy(bitDepth, src, srcStride, dst, dstStride, width, height, isFirst, isLast );
  }
  else if (isLuma(compID))
  {
    assert(frac >= 0 && frac < LUMA_INTERPOLATION_FILTER_SUB_SAMPLE_POSITIONS);
    filterVer<NTAPS_LUMA>(bitDepth, src, srcStride, dst, dstStride, width, height, isFirst, isLast, m_lumaFilter[frac]);
  }
  else
  {
    const UInt csy = getComponentScaleY(compID, fmt);
    assert(frac >=0 && csy<2 && (frac<<(1-csy)) < CHROMA_INTERPOLATION_FILTER_SUB_SAMPLE_POSITIONS);
    filterVer<NTAPS_CHROMA>(bitDepth, src, srcStride, dst, dstStride, width, height, isFirst, isLast, m_chromaFilter[frac<<(1-csy)]);
  }
}

//! \}
