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/*! \file
    \brief Defines basic structures needed for implementing the warp-scoped phase of the epilogue.
          These quantities assume a 'column-major' arrangement of SimtOp instructions, of which
          a row-oriented slice is visible per iteration.
*/

#pragma once

#include "cutlass/matrix_shape.h"
#include "cutlass/layout/matrix.h"

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

namespace cutlass {
namespace epilogue {
namespace warp {

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

template <
  typename WarpShape,            ///< shape of warp-level GEMM (concept: GemmShape)
  typename Operator,             ///< matrix multiply operation (concept: arch::Mma)
  typename Layout,               ///< destination layout in shared memory
  typename MmaSimtPolicy         ///< policy defining lane arrangement (concept: MmaSimtPolicy)
>
struct SimtPolicy;

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

/// Partial specialization for row-major
template <
  typename WarpShape_,           ///< shape of warp-level GEMM (concept: MatrixShape)
  typename Operator_,            ///< matrix multiply operation (concept: arch::Mma)
  typename MmaSimtPolicy_        ///< policy defining lane arrangement (concept: MmaSimtPolicy)
>
struct SimtPolicy<WarpShape_, Operator_, layout::RowMajor, MmaSimtPolicy_> {

  using WarpShape = WarpShape_;
  using Operator = Operator_;
  using MmaSimtPolicy = MmaSimtPolicy_;

  static_assert(!(WarpShape::kM % MmaSimtPolicy::WarpShape::kRow), "Divisibility");
  static_assert(!(WarpShape::kN % MmaSimtPolicy::WarpShape::kColumn), "Divisibility");

  /// Number of iterations
  static int const kIterations = WarpShape::kM / MmaSimtPolicy::WarpShape::kRow;

  /// Number of accumulators written per iteration
  static int const kElementsPerIteration = 
    (WarpShape::kN / MmaSimtPolicy::WarpShape::kColumn);

  /// Total number of accumulators
  static int const kAccumulatorElementCount = kElementsPerIteration * kIterations;

  /// Number of consecutive elements
  static int const kElementsPerAccess = MmaSimtPolicy::LaneMmaShape::kN;

  /// Number of rows per epilogue iteration
  static int const kRowsPerIteration = MmaSimtPolicy::WarpShape::kRow;

  /// Number of accesses made in one iteration
  static int const kAccessesPerIteration = kElementsPerIteration / kElementsPerAccess;

  /// Number of elements in between accumulator chunks of (LaneMmaShape::kM x LaneMmaShape::kN)
  using Delta = MatrixShape<
    MmaSimtPolicy::WarpShape::kRow * MmaSimtPolicy::LaneMmaShape::kM,
    MmaSimtPolicy::WarpShape::kColumn * MmaSimtPolicy::LaneMmaShape::kN
  >;
};

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

} // namespace warp
} // namespace epilogue
} // namespace cutlass

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