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/*! \file
    \brief Defines layout functions used by TensorRef and derived classes for
   pitch-linear memory.
*/
#pragma once

#include "cutlass/cutlass.h"
#include "cutlass/coord.h"

namespace cutlass {
namespace layout {

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

/// Template defining a shape used by pitch-linear operators
template <int Contiguous, int Strided>
struct PitchLinearShape {
    static int const kContiguous = Contiguous;
    static int const kStrided = Strided;
    static int const kCount = Contiguous * Strided;
};

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

/// Coordinate in pitch-linear space
struct PitchLinearCoord : public Coord<2, int> {
public:
    /// Integer-valued index
    using Index = int;

    /// Base type is a Coord of rank=2
    using Base = Coord<2, Index>;

private:
    /// Rows dimension
    static int const kContiguous = 0;

    /// Columns dimension
    static int const kStrided = 1;

public:
    //
    // Methods
    //

    /// Default ctor
    CUTLASS_HOST_DEVICE
    PitchLinearCoord() {}

    /// Constructs from Coord<2>
    CUTLASS_HOST_DEVICE
    PitchLinearCoord(Coord<2, Index> const& coord) : Base(coord) {}

    /// Helper to construct from a row and column
    CUTLASS_HOST_DEVICE
    PitchLinearCoord(Index contiguous_, Index strided_)
            : Base(make_Coord(contiguous_, strided_)) {}

    /// Returns the contiguous dimension
    CUTLASS_HOST_DEVICE
    Index const& contiguous() const { return this->at(kContiguous); }

    /// Returns the contiguous dimension
    CUTLASS_HOST_DEVICE
    Index& contiguous() { return this->at(kContiguous); }

    /// Returns the column of the coordinate
    CUTLASS_HOST_DEVICE
    Index const& strided() const { return this->at(kStrided); }

    /// Returns the column of the coordinate
    CUTLASS_HOST_DEVICE
    Index& strided() { return this->at(kStrided); }

    //
    // Coord operators
    //

    /// Element-wise addition
    CUTLASS_HOST_DEVICE
    PitchLinearCoord operator+(Base const& b) const {
        return PitchLinearCoord(Base::operator+(b));
    }

    /// Element-wise subtraction
    CUTLASS_HOST_DEVICE
    PitchLinearCoord operator-(Base const& b) const {
        return PitchLinearCoord(Base::operator-(b));
    }

    CUTLASS_HOST_DEVICE
    PitchLinearCoord operator-() const {
        return PitchLinearCoord(-at(0), -at(1));
    }

    /// Element-wise multiplication
    CUTLASS_HOST_DEVICE
    PitchLinearCoord operator*(Base const& b) const {
        return PitchLinearCoord(Base::operator*(b));
    }

    /// Element-wise division
    CUTLASS_HOST_DEVICE
    PitchLinearCoord operator/(Base const& b) const {
        return PitchLinearCoord(Base::operator/(b));
    }

    /// In-place addition
    CUTLASS_HOST_DEVICE
    PitchLinearCoord& operator+=(Base const& b) {
        Base::operator+=(b);
        return *this;
    }

    /// In-place subtraction
    CUTLASS_HOST_DEVICE
    PitchLinearCoord& operator-=(Base const& b) {
        Base::operator-=(b);
        return *this;
    }

    /// In-place multiplication
    CUTLASS_HOST_DEVICE
    PitchLinearCoord& operator*=(Base const& b) {
        Base::operator*=(b);
        return *this;
    }

    /// In-place division
    CUTLASS_HOST_DEVICE
    PitchLinearCoord& operator/=(Base const& b) {
        Base::operator/=(b);
        return *this;
    }
};

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

/// Mapping function for pitch-linear memory
class PitchLinear {
public:
    /// Logical rank of tensor
    static int const kRank = 2;

    /// Rank of stride vector
    static int const kStrideRank = 1;

    /// Index type used for coordinates
    using Index = int32_t;

    /// Long index type used for offsets
    using LongIndex = int64_t;

    /// Logical coordinate
    using TensorCoord = PitchLinearCoord;

    /// Stride vector
    using Stride = Coord<kStrideRank, Index>;

private:
    //
    // Data members
    //

    /// Stride data member
    Stride stride_;

public:
    //
    // Methods
    //

    /// Constructor
    CUTLASS_HOST_DEVICE
    PitchLinear(Index ldm = 0) : stride_(ldm) {}

    /// Constructor
    CUTLASS_HOST_DEVICE
    PitchLinear(Stride _stride) : stride_(_stride) {}

    /// Helper returns a layout to a tightly packed tensor
    CUTLASS_HOST_DEVICE
    static PitchLinear packed(TensorCoord const& extent) {
        return PitchLinear(extent.contiguous());
    }

    /// Returns the offset of a coordinate in linear memory.
    /// Assumes coordinate has convention (contiguous, strided)
    CUTLASS_HOST_DEVICE
    LongIndex operator()(TensorCoord const& coord) const {
        return LongIndex(coord.contiguous()) +
               LongIndex(coord.strided()) * LongIndex(stride_[0]);
    }

    /// Returns the logical coordinate given an offset.
    CUTLASS_HOST_DEVICE
    TensorCoord inverse(LongIndex index) const {
        return make_Coord(Index(index % stride_[0]), Index(index / stride_[0]));
    }

    /// Returns the stride of the layout
    CUTLASS_HOST_DEVICE
    Stride stride() const { return stride_; }

    /// Returns the stride of the layout
    CUTLASS_HOST_DEVICE
    Stride& stride() { return stride_; }

    /// Returns the stride of the layout
    CUTLASS_HOST_DEVICE
    Index stride(int rank) const { return stride_[rank]; }

    /// Returns the stride of the layout
    CUTLASS_HOST_DEVICE
    Index& stride(int rank) { return stride_[rank]; }

    /// Compute the number of contiguous elements needed to store a tensor with
    /// the given size
    CUTLASS_HOST_DEVICE
    LongIndex capacity(TensorCoord const& extent) const {
        return extent.strided() * stride_[0];
    }
};

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

}  // namespace layout
}  // namespace cutlass
