// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef EIGEN_CXX11_NEURAL_NETWORKS_SPATIAL_CONVOLUTIONS_H
#define EIGEN_CXX11_NEURAL_NETWORKS_SPATIAL_CONVOLUTIONS_H

namespace Eigen {

namespace internal {

// These optimizations require vector instructions
#ifdef EIGEN_VECTORIZE

// TODO: Consolidate this part of the code with the image patch extraction code
// since they are both very similar.
template <typename NewDimension, DenseIndex Rows, DenseIndex Cols, typename ArgType, typename Device,
          typename Scalar_, typename Index,
          typename nocontract_t, typename contract_t,
          int Side, int packet_size,
          bool inner_dim_contiguous, bool inner_dim_reordered, int Alignment>
class TensorContractionInputMapper<Scalar_, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment>
{
 public:
  typedef Scalar_ Scalar;
  typedef TensorContractionInputMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment> Self;
  typedef TensorContractionSubMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment> SubMapper;
  typedef SubMapper VectorMapper;
  typedef SubMapper LinearMapper;
  typedef typename packet_traits<Scalar>::type Packet;

  EIGEN_DEVICE_FUNC
  TensorContractionInputMapper(const TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>& tensor,
                               const nocontract_t&, const nocontract_t&,
                               const contract_t&, const contract_t&)
      : m_impl(tensor.impl().impl())
  {
    Index patch_rows;
    Index patch_depth;
    if (internal::traits<ArgType>::Layout == ColMajor) {
      patch_depth = tensor.impl().dimensions()[0];
      patch_rows = tensor.impl().dimensions()[1];
      m_patch_cols = tensor.impl().dimensions()[2];
      m_num_patches = tensor.impl().dimensions()[3];
    } else {
      const int NumDims = tensor.impl().dimensions().size();
      patch_depth = tensor.impl().dimensions()[NumDims - 1];
      patch_rows = tensor.impl().dimensions()[NumDims - 2];
      m_patch_cols = tensor.impl().dimensions()[NumDims - 3];
      m_num_patches = tensor.impl().dimensions()[NumDims - 4];
    }
    m_patch_row_inflate_strides = tensor.impl().rowInflateStride();
    m_patch_col_inflate_strides = tensor.impl().colInflateStride();

    m_colStride = patch_rows;

    m_outputRows = tensor.impl().outputRows();
    m_row_strides = tensor.impl().userRowStride();
    m_col_strides = tensor.impl().userColStride();

    m_in_row_strides = tensor.impl().userInRowStride();
    m_in_col_strides = tensor.impl().userInColStride();

    if (internal::traits<ArgType>::Layout == ColMajor) {
      m_inputRows = tensor.impl().impl().dimensions()[1];
      m_inputCols = tensor.impl().impl().dimensions()[2];
    } else {
      const int NumDims = tensor.impl().impl().dimensions().size();
      m_inputRows = tensor.impl().impl().dimensions()[NumDims - 2];
      m_inputCols = tensor.impl().impl().dimensions()[NumDims - 3];
    }

    m_rowInputStride = patch_depth;
    m_colInputStride = patch_depth * m_inputRows;
    m_patchInputStride = patch_depth * m_inputRows * m_inputCols;

    m_rowPaddingTop = tensor.impl().rowPaddingTop();
    m_colPaddingLeft = tensor.impl().colPaddingLeft();

    m_fastInputRowStride = internal::TensorIntDivisor<Index>(m_patch_row_inflate_strides);
    m_fastInputColStride = internal::TensorIntDivisor<Index>(m_patch_col_inflate_strides);
    m_fastNumPatches = internal::TensorIntDivisor<Index>(m_num_patches);
    m_fastColStride = internal::TensorIntDivisor<Index>(m_colStride);
    m_fastOutputRows = internal::TensorIntDivisor<Index>(m_outputRows);
    m_fastDimZero = internal::TensorIntDivisor<Index>(patch_depth);
  }

  EIGEN_DEVICE_FUNC
  TensorContractionInputMapper(const TensorContractionInputMapper& base_mapper) :
      m_impl(base_mapper.m_impl) {
    m_patch_cols = base_mapper.m_patch_cols;
    m_num_patches = base_mapper.m_num_patches;
    m_patch_row_inflate_strides = base_mapper.m_patch_row_inflate_strides;
    m_patch_col_inflate_strides = base_mapper.m_patch_col_inflate_strides;

    m_colStride = base_mapper.m_colStride;

    m_rowInputStride = base_mapper.m_rowInputStride;
    m_colInputStride = base_mapper.m_colInputStride;
    m_patchInputStride = base_mapper.m_patchInputStride;

    m_inputRows = base_mapper.m_inputRows;
    m_inputCols = base_mapper.m_inputCols;

    m_outputRows = base_mapper.m_outputRows;
    m_row_strides = base_mapper.m_row_strides;
    m_col_strides = base_mapper.m_col_strides;

    m_in_row_strides = base_mapper.m_in_row_strides;
    m_in_col_strides = base_mapper.m_in_col_strides;

    m_rowPaddingTop = base_mapper.m_rowPaddingTop;
    m_colPaddingLeft = base_mapper.m_colPaddingLeft;

    m_fastInputRowStride = base_mapper.m_fastInputRowStride;
    m_fastInputColStride = base_mapper.m_fastInputColStride;
    m_fastNumPatches = base_mapper.m_fastNumPatches;
    m_fastColStride = base_mapper.m_fastColStride;
    m_fastOutputRows = base_mapper.m_fastOutputRows;
    m_fastDimZero = base_mapper.m_fastDimZero;
  }

 // If true, turns off some optimizations for loading packets since the image
  // patches are "non-standard" such as there are non-trivial strides or
  // inflations in the input.
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE bool nonStandardPatches() const {
    return m_in_row_strides != 1 || m_in_col_strides != 1 || m_patch_row_inflate_strides != 1 || m_patch_col_inflate_strides != 1;
  }

  EIGEN_DEVICE_FUNC
  EIGEN_STRONG_INLINE SubMapper getSubMapper(Index i, Index j) const {
    return SubMapper(*this, i, j);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_STRONG_INLINE LinearMapper getLinearMapper(Index i, Index j) const {
    return LinearMapper(*this, i, j);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Scalar operator()(Index row) const {
    Index rowIndex, colIndex, otherIndex;
    computeBaseIndices(0, rowIndex, colIndex, otherIndex);
    return loadCoeff(row, rowIndex, colIndex, otherIndex);
  }

  // Load the coefficient at the patchIndex location instead of the usual m_rowIndex,
  // m_colIndex, m_otherIndex. This is currently only used by the gpu code.  EIGEN_DEVICE_FUNC
  EIGEN_DEVICE_FUNC
  EIGEN_STRONG_INLINE Scalar operator()(Index row, Index patchIndex) const {
    Index rowIndex, colIndex, otherIndex;
    computeBaseIndices(patchIndex, rowIndex, colIndex, otherIndex);
    return loadCoeff(row, rowIndex, colIndex, otherIndex);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Packet loadPacket(Index row) const {
    Index rowIndex, colIndex, otherIndex;
    computeBaseIndices(0, rowIndex, colIndex, otherIndex);
    return loadPacket(row, rowIndex, colIndex, otherIndex);
  }

  // Load the packet at the patchIndex location instead of the usual m_rowIndex,
  // m_colIndex, m_otherIndex. This is currently only used by the gpu code.
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Packet loadPacket(Index row, Index patchIndex) const {
    Index rowIndex, colIndex, otherIndex;
    computeBaseIndices(patchIndex, rowIndex, colIndex, otherIndex);
    return loadPacket(row, rowIndex, colIndex, otherIndex);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE const TensorEvaluator<ArgType, Device>& impl() const { return m_impl; }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index patchDepth() const { return m_rowInputStride; }
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index patchRows() const { return m_colStride; }
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index patchCols() const { return m_patch_cols; }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Packet packetNoPadding(const Index depth, const Index baseIndex) const {
    const Index inputIndex = depth + baseIndex;
    return m_impl.template packet<Unaligned>(inputIndex);
  }

 private:
  friend class TensorContractionSubMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment>;

  EIGEN_DEVICE_FUNC
  EIGEN_STRONG_INLINE Scalar loadCoeff(Index patchId, Index rowIndex, Index colIndex, Index otherIndex) const {
    // Find the offset of the element wrt the location of the first element.
    const Index patchOffset = patchId / m_fastDimZero;

    const Index colOffset = patchOffset / m_fastColStride;
    const Index inputCol = colIndex + colOffset * m_in_col_strides;
    const Index origInputCol = (m_patch_col_inflate_strides == 1) ? inputCol : ((inputCol >= 0) ? (inputCol / m_fastInputColStride) : 0);
    const Index rowOffset = patchOffset - colOffset * m_colStride;
    const Index inputRow = rowIndex + rowOffset * m_in_row_strides;
    const Index origInputRow = (m_patch_row_inflate_strides == 1) ? inputRow : ((inputRow >= 0) ? (inputRow / m_fastInputRowStride) : 0);
    if (origInputCol < 0 | origInputRow < 0 | origInputCol >= m_inputCols | origInputRow >= m_inputRows |
        (inputCol != origInputCol * m_patch_col_inflate_strides) | (inputRow != origInputRow * m_patch_row_inflate_strides)) {
      return Scalar(0);
    }
    const Index depth = patchId - patchOffset * patchDepth();
    const Index inputIndex = depth + origInputRow * m_rowInputStride + origInputCol * m_colInputStride + otherIndex;
    return m_impl.coeff(inputIndex);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_STRONG_INLINE Scalar loadCoeffStandard(Index patchId, Index rowIndex, Index colIndex, Index otherIndex) const {
    eigen_assert(!nonStandardPatches());

    // Find the offset of the element wrt the location of the first element.
    const Index patchOffset = patchId / m_fastDimZero;

    const Index colOffset = patchOffset / m_fastColStride;
    const Index inputCol = colIndex + colOffset;
    const Index rowOffset = patchOffset - colOffset * m_colStride;
    const Index inputRow = rowIndex + rowOffset;
    if (inputCol < 0 || inputCol >= m_inputCols || inputRow < 0 || inputRow >= m_inputRows) {
      return Scalar(0);
    }
    const Index depth = patchId - patchOffset * patchDepth();
    const Index inputIndex = depth + inputRow * m_rowInputStride + inputCol * m_colInputStride + otherIndex;
    return m_impl.coeff(inputIndex);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Packet loadPacket(Index patchId, Index rowIndex, Index colIndex, Index otherIndex) const {
    const Index packetSize = internal::unpacket_traits<Packet>::size;
    EIGEN_STATIC_ASSERT(packetSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
    eigen_assert(patchId < patchDepth()*patchRows()*m_patch_cols);

    if (nonStandardPatches()) {
      return packetWithPossibleZero(patchId, rowIndex, colIndex, otherIndex);
    }
    return loadPacketStandard(patchId, rowIndex, colIndex, otherIndex);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Packet loadPacketStandard(Index patchId, Index rowIndex, Index colIndex, Index otherIndex) const {
    const Index packetSize = internal::unpacket_traits<Packet>::size;
    EIGEN_STATIC_ASSERT(packetSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
    eigen_assert(patchId < patchDepth()*patchRows()*m_patch_cols);

    eigen_assert(!nonStandardPatches());

    if ((patchDepth() % packetSize) == 0) {
      return loadPacketFast(patchId, rowIndex, colIndex, otherIndex);
    }
    else {
      const Index patchOffsets[2] = {patchId / m_fastDimZero, (patchId + packetSize - 1) / m_fastDimZero};

      const Index colOffsets[2] = {patchOffsets[0] / m_fastColStride, patchOffsets[1] / m_fastColStride};

      const Index inputCols[2] = {colIndex + colOffsets[0], colIndex + colOffsets[1]};
      if (inputCols[0] >= m_inputCols | inputCols[1] < 0) {
        // all zeros
        return internal::pset1<Packet>(Scalar(0));
      }

      if (inputCols[0] == inputCols[1]) {
        const Index rowOffsets[2] = {patchOffsets[0] - colOffsets[0]*m_colStride, patchOffsets[1] - colOffsets[1]*m_colStride};
        eigen_assert(rowOffsets[0] <= rowOffsets[1]);
        const Index inputRows[2] = {rowIndex + rowOffsets[0], rowIndex + rowOffsets[1]};

        if (inputRows[0] >= m_inputRows | inputRows[1] < 0) {
          // all zeros
          return internal::pset1<Packet>(Scalar(0));
        }

        if (inputRows[0] >= 0 & inputRows[1] < m_inputRows) {
          // no padding
          const Index depth = patchId - patchOffsets[0] * patchDepth();
          const Index inputIndex = depth + inputRows[0] * m_rowInputStride + inputCols[0] * m_colInputStride + otherIndex;
          return m_impl.template packet<Unaligned>(inputIndex);
        }
      }
    }
    return packetWithPossibleZero(patchId, rowIndex, colIndex, otherIndex);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Packet loadPacketFast(Index patchId, Index rowIndex, Index colIndex, Index otherIndex) const {
    const Index packetSize = internal::unpacket_traits<Packet>::size;
    EIGEN_STATIC_ASSERT(packetSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
    eigen_assert(patchId < patchDepth()*patchRows()*m_patch_cols);

    eigen_assert(!nonStandardPatches());
    eigen_assert((patchDepth() % packetSize) == 0);
    // Find the offset of the element wrt the location of the first element.
    const Index patchOffset = patchId / m_fastDimZero;
    eigen_assert((patchId + packetSize - 1)  / m_fastDimZero == patchOffset);

    const Index colOffset = patchOffset / m_fastColStride;
    const Index inputCol = colIndex + colOffset;
    const Index rowOffset = patchOffset - colOffset*m_colStride;
    const Index inputRow = rowIndex + rowOffset;
    if (inputCol < 0 | inputRow < 0 | inputCol >= m_inputCols | inputRow >= m_inputRows) {
      // all zeros
      return internal::pset1<Packet>(Scalar(0));
    }
    // no padding
    const Index depth = patchId - patchOffset * patchDepth();
    const Index inputIndex = depth + inputRow * m_rowInputStride + inputCol * m_colInputStride + otherIndex;
    return m_impl.template packet<Unaligned>(inputIndex);
  }

  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Packet packetWithPossibleZero(Index patchId, Index rowIndex, Index colIndex, Index otherIndex) const
  {
    const int packetSize = internal::unpacket_traits<Packet>::size;
    EIGEN_ALIGN_MAX typename internal::remove_const<Scalar>::type values[packetSize];
    for (int i = 0; i < packetSize; ++i) {
      values[i] = loadCoeff(patchId+i, rowIndex, colIndex, otherIndex);
    }
    Packet rslt = internal::pload<Packet>(values);
    return rslt;
  }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void computeBaseIndices(Index patchIndex, Index& rowIndex, Index& colIndex, Index& otherIndex) const {
    const int NumInputDims = array_size<typename TensorEvaluator<ArgType, Device>::Dimensions>::value;
    otherIndex = (NumInputDims == 3) ? 0 : patchIndex / m_fastNumPatches;
    const Index patch2DIndex = (NumInputDims == 3) ? patchIndex : (patchIndex - otherIndex * m_num_patches);
    otherIndex *= m_patchInputStride;
    colIndex = patch2DIndex / m_fastOutputRows;
    rowIndex = patch2DIndex - colIndex * m_outputRows;
    colIndex = colIndex * m_col_strides - m_colPaddingLeft;
    rowIndex = rowIndex * m_row_strides - m_rowPaddingTop;
  }

  Index m_patch_cols;    // number of colums in the patch
  Index m_num_patches;   // number of patches to extract.
  Index m_patch_row_inflate_strides;  // the strides for row inflation in the image patch
  Index m_patch_col_inflate_strides;  // the strides for col inflation in the image patch
  // Fast representation of inflation strides.
  internal::TensorIntDivisor<Index> m_fastInputRowStride;
  internal::TensorIntDivisor<Index> m_fastInputColStride;

  Index m_otherStride;
  Index m_colStride;
  internal::TensorIntDivisor<Index> m_fastNumPatches;
  internal::TensorIntDivisor<Index> m_fastColStride;

  Index m_rowInputStride;     // row stride in the input tensor
  Index m_colInputStride;     // col stride in the input tensor
  Index m_patchInputStride;   // patch stride in the input tensor

  Index m_inputRows;     // Number of rows in the input tensor
  Index m_inputCols;     // Number of cols in the input tensor

  Index m_outputRows;    // Number of patch rows

  Index m_row_strides;   // User specified row stride
  Index m_col_strides;   // User specified col stride

  Index m_in_row_strides;  // User specified input row stride
  Index m_in_col_strides;  // User specified input col stride

  Index m_rowPaddingTop;    // Row padding
  Index m_colPaddingLeft;   // Column padding

  internal::TensorIntDivisor<Index> m_fastOutputRows;
  internal::TensorIntDivisor<Index> m_fastDimZero;

  const TensorEvaluator<ArgType, Device> m_impl;
};


template <typename NewDimension, DenseIndex Rows, DenseIndex Cols, typename ArgType, typename Device,
          typename Scalar, typename Index,
          typename nocontract_t, typename contract_t,
          int Side, int packet_size,
          bool inner_dim_contiguous, bool inner_dim_reordered, int Alignment>
class TensorContractionSubMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment>
{
 public:
  typedef typename packet_traits<Scalar>::type Packet;
  typedef typename packet_traits<Scalar>::half HalfPacket;

  typedef TensorContractionInputMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment> ParentMapper;
  typedef TensorContractionSubMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment> Self;
  typedef Self LinearMapper;

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorContractionSubMapper(const ParentMapper& base_mapper, Index vert_offset, Index horiz_offset)
      : m_base_mapper(base_mapper), m_depth_offset(vert_offset), m_col_offset(horiz_offset) {
    m_base_mapper.computeBaseIndices(m_col_offset, m_rowIndex, m_colIndex, m_otherIndex);
  }
  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorContractionSubMapper(const Self& base_mapper, Index vert_offset, Index horiz_offset)
      : m_base_mapper(base_mapper.m_base_mapper), m_depth_offset(vert_offset+base_mapper.m_depth_offset), m_col_offset(horiz_offset+base_mapper.m_col_offset) {
    m_base_mapper.computeBaseIndices(m_col_offset, m_rowIndex, m_colIndex, m_otherIndex);
  }
  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Scalar operator()(Index i) const {
    return m_base_mapper.loadCoeff(i + m_depth_offset, m_rowIndex, m_colIndex, m_otherIndex);
  }
  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Scalar operator()(Index i, Index j) const {
    return m_base_mapper(i + m_depth_offset, j + m_col_offset);
  }

  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Packet loadPacket(Index i) const {
   return m_base_mapper.loadPacket(i + m_depth_offset, m_rowIndex, m_colIndex, m_otherIndex);
  }
  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Packet loadPacket(Index i, Index j) const {
    return m_base_mapper.template loadPacket(i + m_depth_offset, j + m_col_offset);
  }

  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Scalar loadCoeffStandard(Index i) const {
    return m_base_mapper.loadCoeffStandard(i + m_depth_offset, m_rowIndex, m_colIndex, m_otherIndex);
  }

  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Packet loadPacketFast(Index i) const {
   return m_base_mapper.loadPacketFast(i + m_depth_offset, m_rowIndex, m_colIndex, m_otherIndex);
  }
  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE Packet loadPacketStandard(Index i) const {
   return m_base_mapper.loadPacketStandard(i + m_depth_offset, m_rowIndex, m_colIndex, m_otherIndex);
  }
  template <typename Packet>
  EIGEN_DEVICE_FUNC bool aligned(Index) const {
    return false;
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE bool nonStandardPatches() const {
    return m_base_mapper.nonStandardPatches();
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index patchDepth() const { return m_base_mapper.m_rowInputStride; }
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index patchRows() const { return m_base_mapper.m_colStride; }
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index patchCols() const { return m_base_mapper.m_patch_cols; }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Packet packetNoPadding(const Index depth, const Index baseIndex) const {
    const Index inputIndex = depth + baseIndex;
    return m_base_mapper.m_impl.template packet<Unaligned>(inputIndex);
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE bool padRow(const Index row) const {
    const Index r = m_rowIndex + row;
    return r < 0 | r >= m_base_mapper.m_inputRows;
  }
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE bool padCol(const Index col) const {
    const Index c = m_colIndex + col;
    return c < 0 | c >= m_base_mapper.m_inputCols;
    }
  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index baseIndex(const Index row, const Index col) const {
    const Index r = m_rowIndex + row;
    const Index c = m_colIndex + col;
    return r * m_base_mapper.m_rowInputStride + c * m_base_mapper.m_colInputStride + m_otherIndex;
  }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index rowOffset() const {
    const Index patchOffset = m_depth_offset / m_base_mapper.m_fastDimZero;
    const Index colOffset = patchOffset / m_base_mapper.m_fastColStride;
    return patchOffset-colOffset*m_base_mapper.m_colStride;
    }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index colOffset() const {
    const Index patchOffset = m_depth_offset / m_base_mapper.m_fastDimZero;
    const Index colOffset = patchOffset / m_base_mapper.m_fastColStride;
    return colOffset;
    }

  EIGEN_DEVICE_FUNC
  EIGEN_ALWAYS_INLINE Index depthOffset() const {
    const Index patchOffset = m_depth_offset % m_base_mapper.patchDepth();
    return patchOffset;
  }

  EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE LinearMapper getLinearMapper(Index i, Index j) const {
    return LinearMapper(m_base_mapper, i + m_depth_offset, j + m_col_offset);
 }

 private:
  const ParentMapper& m_base_mapper;  // that was a reference before
  Index m_depth_offset;  // First row in the input matrix
  Index m_col_offset;    // First col in the input matrix

  Index m_rowIndex;        // precomputed row index corresponding to the col offset
  Index m_colIndex;        // precomputed col index corresponding to the col offset
  Index m_otherIndex;      // precomputed other index corresponding to the col offset
};


template <typename NewDimension, DenseIndex Rows, DenseIndex Cols, typename ArgType, typename Device,
          typename Scalar, typename Index,
          typename nocontract_t, typename contract_t,
          int Side, int packet_size,
          bool inner_dim_contiguous, bool inner_dim_reordered, int Alignment, int nr>
struct gemm_pack_rhs<Scalar, Index, TensorContractionSubMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment>, nr, ColMajor, false, false> {

  typedef TensorContractionSubMapper<Scalar, Index, Side, TensorEvaluator<const TensorReshapingOp<NewDimension, const TensorImagePatchOp<Rows, Cols, ArgType> >, Device>, nocontract_t, contract_t, packet_size, inner_dim_contiguous, inner_dim_reordered, Alignment> SubMapper;
  typedef SubMapper DataMapper;

  EIGEN_DEVICE_FUNC
  static inline Index ceil_div(Index a, Index b) {
    return (a + b - 1) / b;
  }

  EIGEN_DEVICE_FUNC
  EIGEN_DONT_INLINE void operator()(Scalar* block, const DataMapper& rhs, Index depth, Index cols, Index stride=0, Index offset=0) const {
    eigen_assert(stride == 0);
    eigen_assert(offset == 0);

    EIGEN_STATIC_ASSERT((nr == 4), YOU_MADE_A_PROGRAMMING_MISTAKE);
    typedef typename DataMapper::LinearMapper LinearMapper;
    typedef typename packet_traits<Scalar>::type Packet;

    const Index packet_cols4 = (cols/4) * 4;
    const Index peeled_k = (depth/packet_size) * packet_size;
    const bool non_standard_patches = rhs.nonStandardPatches();

    for(Index j2=0; j2<packet_cols4; j2+=4)
    {
      const SubMapper dm0 = rhs.getLinearMapper(0, j2 + 0);
      const SubMapper dm1 = rhs.getLinearMapper(0, j2 + 1);
      const SubMapper dm2 = rhs.getLinearMapper(0, j2 + 2);
      const SubMapper dm3 = rhs.getLinearMapper(0, j2 + 3);

      Index k=0;
      if((packet_size%4)==0 && !non_standard_patches)
      {
        const Index patch_depth = rhs.patchDepth();
        if ((patch_depth % packet_size) == 0) {
          const Index patch_cols = rhs.patchCols();
          const Index patch_rows = rhs.patchRows();

          const Index startCol = rhs.colOffset();
          const Index max_cols = std::min<Index>(ceil_div(peeled_k, patch_rows*patch_depth)+startCol, patch_cols);

          for (Index c = startCol; c < max_cols; ++c) {
            eigen_assert(k < peeled_k);
            const Index startRow = (c == startCol) ? rhs.rowOffset() : 0;
            const Index max_rows = std::min<Index>(ceil_div(peeled_k-c*patch_rows*patch_depth, patch_depth)+startRow, patch_rows);

            const bool pad_col0 = dm0.padCol(c);
            const bool pad_col1 = dm1.padCol(c);
            const bool pad_col2 = dm2.padCol(c);
            const bool pad_col3 = dm3.padCol(c);
            for (Index r = startRow; r < max_rows; ++r) {
              eigen_assert(k < peeled_k);
              const bool pad0 = pad_col0 || dm0.padRow(r);
              const bool pad1 = pad_col1 || dm1.padRow(r);
              const bool pad2 = pad_col2 || dm2.padRow(r);
              const bool pad3 = pad_col3 || dm3.padRow(r);

              const Index idx0 = dm0.baseIndex(r, c);
              const Index idx1 = dm1.baseIndex(r, c);
              const Index idx2 = dm2.baseIndex(r, c);
              const Index idx3 = dm3.baseIndex(r, c);

              const Index startDepth = ((c == startCol) && (r == startRow)) ? rhs.depthOffset() : 0;
              const Index max_depth = std::min<Index>(peeled_k-c*patch_rows*patch_depth-r*patch_depth+startDepth, patch_depth);
              eigen_assert((max_depth-startDepth) % packet_size == 0);
              for (Index d = startDepth; d < max_depth; d += packet_size) {
                eigen_assert(k < peeled_k);
                PacketBlock<Packet, 4> kernel;
                kernel.packet[0] = pad0 ? pset1<Packet>(0) : rhs.packetNoPadding(d, idx0);
                kernel.packet[1] = pad1 ? pset1<Packet>(0) : rhs.packetNoPadding(d, idx1);
                kernel.packet[2] = pad2 ? pset1<Packet>(0) : rhs.packetNoPadding(d, idx2);
                kernel.packet[3] = pad3 ? pset1<Packet>(0) : rhs.packetNoPadding(d, idx3);
                ptranspose(kernel);
                pstoreu(block+0*packet_size, kernel.packet[0]);
                pstoreu(block+1*packet_size, kernel.packet[1]);
                pstoreu(block+2*packet_size, kernel.packet[2]);
                pstoreu(block+3*packet_size, kernel.packet[3]);
                block+=4*packet_size;
                k += packet_size;
              }
            }
          }

          for(; k<peeled_k; k+=packet_size) {
            PacketBlock<Packet, 4> kernel;
            kernel.packet[0] = dm0.loadPacketFast(k);
            kernel.packet[1] = dm1.loadPacketFast(k);
            kernel.packet[2] = dm2.loadPacketFast(k);
            kernel.packet[3] = dm3.loadPacketFast(k);
            ptranspose(kernel);
            pstoreu(block+0*packet_size, kernel.packet[0]);
            pstoreu(block+1*packet_size, kernel.packet[1]);
            pstoreu(block+2*packet_size, kernel.packet[2]);
            pstoreu(block+3*packet_size, kernel.packet[3]);
            block+=4*packet_size;
          }
        }
        else {
          for(; k<peeled_k; k+=packet_size) {
            PacketBlock<Packet, 4> kernel;
            kernel.packet[0] = dm0.loadPacketStandard(k);
            kernel.packet[1] = dm1.loadPacketStandard(k);
            kernel.packet[2] = dm2.loadPacketStandard(k);
            kernel.packet[3] = dm3.loadPacketStandard(k);
            ptranspose(kernel);
            pstoreu(block+0*packet_size, kernel.packet[0]);
            pstoreu(block+1*packet_size, kernel.packet[1]);
            pstoreu(block+2*packet_size, kernel.packet[2]);
            pstoreu(block+3*packet_size, kernel.packet[3]);
            block+=4*packet_size;
          }
        }
      }
      if (!rhs.nonStandardPatches()) {
        for(; k<depth; k++)
        {
          block[0] = dm0.loadCoeffStandard(k);
          block[1] = dm1.loadCoeffStandard(k);
          block[2] = dm2.loadCoeffStandard(k);
          block[3] = dm3.loadCoeffStandard(k);
          block += 4;
        }
      }
      else {
        for(; k<depth; k++)
        {
          block[0] = dm0(k);
          block[1] = dm1(k);
          block[2] = dm2(k);
          block[3] = dm3(k);
          block += 4;
        }
      }
    }

    // copy the remaining columns one at a time (nr==1)
    for(Index j2=packet_cols4; j2<cols; ++j2)
    {
      const SubMapper dm0 = rhs.getLinearMapper(0, j2);
      for(Index k=0; k<depth; k++)
      {
        *block = dm0(k);
        block += 1;
      }
    }
  }
};

#endif  // EIGEN_VECTORIZE
}  // end namespace internal


/** SpatialConvolution
  * \ingroup CXX11_NeuralNetworks_Module
  *
  * \brief Applies a 2D convolution over a multichannel input image.
  *
  * The input parameter is expected to be a tensor with a rank of 3 or more (channels, height, width, and optionally others)
  * The kernel parameter is expected to be a 4D tensor (filters, channels, kernel_height, kernel_width)
  * The input and the kernel must both be in col-major layout. The result will also be in col-major layout.
  *
  * If col_in_stride, row_in_stride > 1, then applies convolution with holes (aka atrous convolution), sampling every col_in_stride, row_in_stride input pixels.
  *
  * The result can be assigned to a tensor of rank equal to the rank of the input. The dimensions of the result will be filters, height, width (and others if applicable).
  *
  * It is possible to swap the order of the width and height dimensions provided that the same order is used in the input, the kernel, and the output.
  *
  */
template <typename Input, typename Kernel>
EIGEN_DEVICE_FUNC
EIGEN_ALWAYS_INLINE
static const typename internal::conditional<
  internal::traits<Input>::Layout == ColMajor,
  TensorReshapingOp<const DSizes<typename internal::traits<Input>::Index, internal::traits<Input>::NumDimensions>, const TensorContractionOp<const array<IndexPair<typename internal::traits<Input>::Index>, 1>, const TensorReshapingOp<const DSizes<typename internal::traits<Input>::Index, 2>, const Kernel>, const TensorReshapingOp<const DSizes<typename internal::traits<Input>::Index, 2>, const TensorImagePatchOp<Dynamic, Dynamic, const Input> > > >,
  TensorReshapingOp<const DSizes<typename internal::traits<Input>::Index, internal::traits<Input>::NumDimensions>, const TensorContractionOp<const array<IndexPair<typename internal::traits<Input>::Index>, 1>, const TensorReshapingOp<const DSizes<typename internal::traits<Input>::Index, 2>, const TensorImagePatchOp<Dynamic, Dynamic, const Input> >, const TensorReshapingOp<const DSizes<typename internal::traits<Input>::Index, 2>, const Kernel> > > >::type
SpatialConvolution(const Input& input, const Kernel& kernel, const DenseIndex row_stride = 1, const DenseIndex col_stride = 1, const PaddingType padding_type = PADDING_SAME, const DenseIndex row_in_stride = 1, const DenseIndex col_in_stride = 1) {

  typedef typename internal::traits<Input>::Index TensorIndex;
  TensorRef<Tensor<typename internal::traits<Input>::Scalar, internal::traits<Input>::NumDimensions, internal::traits<Input>::Layout, TensorIndex> > in(input);
  TensorRef<Tensor<typename internal::traits<Kernel>::Scalar, internal::traits<Kernel>::NumDimensions, internal::traits<Kernel>::Layout, TensorIndex> > kern(kernel);

  EIGEN_STATIC_ASSERT(internal::traits<Input>::Layout == internal::traits<Kernel>::Layout, YOU_MADE_A_PROGRAMMING_MISTAKE);
  const bool isColMajor = (internal::traits<Input>::Layout == ColMajor);

  const int NumDims = internal::traits<Input>::NumDimensions;

  // Number of filters to apply. This is the same as the output depth of the result
  const TensorIndex kernelFilters = isColMajor ? kern.dimensions()[0] : kern.dimensions()[3];
  // Number of channels. This is the same as the input depth.
  const TensorIndex kernelChannels = isColMajor ? kern.dimensions()[1] : kern.dimensions()[2];
  const TensorIndex kernelRows = isColMajor ? kern.dimensions()[2] : kern.dimensions()[1];
  const TensorIndex kernelCols = isColMajor ? kern.dimensions()[3] : kern.dimensions()[0];

  const DenseIndex kernelRowsEff = kernelRows + (kernelRows - 1) * (row_in_stride - 1);
  const DenseIndex kernelColsEff = kernelCols + (kernelCols - 1) * (col_in_stride - 1);

  array<IndexPair<TensorIndex>, 1> contract_dims;
  contract_dims[0] = IndexPair<TensorIndex>(1, 0);

  const TensorIndex InputRows = isColMajor ? in.dimension(1) : in.dimension(NumDims - 2);
  const TensorIndex InputCols = isColMajor ? in.dimension(2) : in.dimension(NumDims - 3);

  TensorIndex out_height;
  TensorIndex out_width;
  switch (padding_type) {
    case PADDING_VALID:
      out_height = numext::ceil((InputRows - kernelRowsEff + 1.f) / static_cast<float>(row_stride));
      out_width = numext::ceil((InputCols - kernelColsEff + 1.f) / static_cast<float>(col_stride));
      break;
    case PADDING_SAME:
      out_height = numext::ceil(InputRows / static_cast<float>(row_stride));
      out_width = numext::ceil(InputCols / static_cast<float>(col_stride));
      break;
    default:
      eigen_assert(false && "unexpected padding");
  }

  // Molds the output of the patch extraction code into a 2d tensor:
  // - the first dimension (dims[0]): the patch values to be multiplied with the kernels
  // - the second dimension (dims[1]): everything else
  DSizes<TensorIndex, 2> pre_contract_dims;
  if (isColMajor) {
    pre_contract_dims[0] = kernelChannels * kernelRows * kernelCols;
    pre_contract_dims[1] = out_height * out_width;
    for (int i = 3; i < NumDims; ++i) {
      pre_contract_dims[1] *= in.dimension(i);
    }
  } else {
    pre_contract_dims[1] = kernelChannels * kernelRows * kernelCols;
    pre_contract_dims[0] = out_height * out_width;
    for (int i = 0; i < NumDims - 3; ++i) {
      pre_contract_dims[0] *= in.dimension(i);
    }
  }

  // Molds the output of the contraction into the shape expected by the used
  // (assuming this is ColMajor):
  // - 1st dim: kernel filters
  // - 2nd dim: output height
  // - 3rd dim: output width
  // - 4th dim and beyond: everything else including batch size
  DSizes<TensorIndex, NumDims> post_contract_dims;
  if (isColMajor) {
    post_contract_dims[0] = kernelFilters;
    post_contract_dims[1] = out_height;
    post_contract_dims[2] = out_width;
    for (int i = 3; i < NumDims; ++i) {
      post_contract_dims[i] = in.dimension(i);
    }
  } else {
    post_contract_dims[NumDims - 1] = kernelFilters;
    post_contract_dims[NumDims - 2] = out_height;
    post_contract_dims[NumDims - 3] = out_width;
    for (int i = 0; i < NumDims - 3; ++i) {
      post_contract_dims[i] = in.dimension(i);
    }
  }

  DSizes<TensorIndex, 2> kernel_dims;
  if (isColMajor) {
    kernel_dims[0] = kernelFilters;
    kernel_dims[1] = kernelChannels * kernelRows * kernelCols;
  } else {
    kernel_dims[0] = kernelChannels * kernelRows * kernelCols;
    kernel_dims[1] = kernelFilters;
  }
  // TODO(yangke): choose() is defined in TensorContraction.h -- consider
  // moving it to somewhere more "common".
  return choose(Cond<internal::traits<Input>::Layout == ColMajor>(),
                kernel.reshape(kernel_dims).contract(input.extract_image_patches(kernelRows, kernelCols, row_stride, col_stride, row_in_stride, col_in_stride, padding_type).reshape(pre_contract_dims), contract_dims).reshape(post_contract_dims),
                input.extract_image_patches(kernelRows, kernelCols, row_stride, col_stride, row_in_stride, col_in_stride, padding_type).reshape(pre_contract_dims).contract(kernel.reshape(kernel_dims), contract_dims).reshape(post_contract_dims));
}

} // end namespace Eigen

#endif // EIGEN_CXX11_NEURAL_NETWORKS_SPATIAL_CONVOLUTIONS_H