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/*! \file
    \brief Template for a double-buffered threadblock-scoped GEMM kernel.
*/

#pragma once

#include "cutlass/tensor_ref.h"
#include "cutlass/aligned_buffer.h"
#include "cutlass/arch/memory.h"
#include "cutlass/array.h"
#include "cutlass/cutlass.h"
#include "cutlass/gemm/gemm.h"
#include "cutlass/matrix_shape.h"
#include "cutlass/numeric_types.h"

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

namespace cutlass {
namespace gemm {
namespace threadblock {

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

/// Policy object describing MmaTensorOp
template <
    /// Warp-level GEMM operator (concept: gemm::warp::Mma)
    typename Operator_,
    /// Padding used for A operand in shared memory (concept: MatrixShape)
    typename SmemPaddingA_,
    /// Padding used for B operand in shared memory (concept: MatrixShape)
    typename SmemPaddingB_,
    /// Number of partitions of K dimension of GEMM
    int PartitionsK = 1>
struct MmaPolicy {
  /// Warp-level GEMM operator (concept: gemm::warp::MmaTensorOp or gemm::warp::MmaSimt)
  using Operator = Operator_;

  /// Padding used for A operand in shared memory
  using SmemPaddingA = SmemPaddingA_;

  /// Padding used for B operand in shared memory
  using SmemPaddingB = SmemPaddingB_;

  /// Number of partitions of K dimension
  static int const kPartitionsK = PartitionsK;
};

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

/// Structure to compute the matrix product targeting CUDA cores and SIMT math
/// instructions.
template <
    /// Size of the Gemm problem - concept: gemm::GemmShape<>
    typename Shape_,
    /// Policy describing tuning details (concept: MmaPolicy)
    typename Policy_,
    /// Number of stages,
    int Stages,
    /// Used for partial specialization
    typename Enable = bool>
class MmaBase {
 public:
  ///< Size of the Gemm problem - concept: gemm::GemmShape<>
  using Shape = Shape_;

  ///< Policy describing tuning details
  using Policy = Policy_;

  //
  // Dependent types
  //

  /// Warp-level Mma
  using Operator = typename Policy::Operator;

  /// Shape describing the overall GEMM computed from shared memory
  /// by each warp.
  using WarpGemm = typename Policy::Operator::Shape;

  /// Shape describing the number of warps filling the CTA
  using WarpCount = GemmShape<Shape::kM / WarpGemm::kM,
                              Shape::kN / WarpGemm::kN,
                              Shape::kK / WarpGemm::kK>;

  /// Number of warp-level GEMM oeprations
  static int const kWarpGemmIterations =
      (WarpGemm::kK / Operator::Policy::MmaShape::kK);

  /// Number of stages
  static int const kStages = Stages;

  /// Tensor reference to the A operand
  using TensorRefA = TensorRef<typename Operator::ElementA, typename Operator::LayoutA>;

  /// Tensor reference to the B operand
  using TensorRefB = TensorRef<typename Operator::ElementB, typename Operator::LayoutB>;

  static_assert(kWarpGemmIterations > 1,
                "The pipelined structure requires at least two warp-level "
                "GEMM operations.");

  static_assert((kWarpGemmIterations % 2) == 0,
                "Inner loop iteration must be an even number.");

  //
  // Nested structs
  //

  /// Shared storage object needed by threadblock-scoped GEMM
  class SharedStorage {
   public:
    //
    // Type definitions
    //

    /// Shape of the A matrix operand in shared memory
    using ShapeA = MatrixShape<Shape::kM + Policy::SmemPaddingA::kRow,
                               Shape::kK * kStages +
                                   Policy::SmemPaddingA::kColumn>;

    /// Shape of the B matrix operand in shared memory
    using ShapeB =
        MatrixShape<Shape::kK * kStages + Policy::SmemPaddingB::kRow,
                    Shape::kN + Policy::SmemPaddingB::kColumn>;

   public:
    //
    // Data members
    //

    /// Buffer for A operand
    AlignedBuffer<typename Operator::ElementA, ShapeA::kCount> operand_A;

    /// Buffer for B operand
    AlignedBuffer<typename Operator::ElementB, ShapeB::kCount> operand_B;

   public:

    //
    // Methods
    //

    /// Returns a layout object for the A matrix
    CUTLASS_DEVICE
    static typename Operator::LayoutA LayoutA() {
      return Operator::LayoutA::packed({ShapeA::kRow, ShapeA::kColumn});
    }

    /// Returns a layout object for the B matrix
    CUTLASS_HOST_DEVICE
    static typename Operator::LayoutB LayoutB() {
      return Operator::LayoutB::packed({ShapeB::kRow, ShapeB::kColumn});
    }

    /// Returns a TensorRef to the A operand
    CUTLASS_HOST_DEVICE
    TensorRefA operand_A_ref() {
      return TensorRefA{operand_A.data(), LayoutA()};
    }

    /// Returns a TensorRef to the B operand
    CUTLASS_HOST_DEVICE
    TensorRefB operand_B_ref() {
      return TensorRefB{operand_B.data(), LayoutB()};
    }
  };

 protected:

  //
  // Data members
  //

  /// Iterator to load a warp-scoped tile of A operand from shared memory
  typename Operator::IteratorA warp_tile_iterator_A_;

  /// Iterator to load a warp-scoped tile of B operand from shared memory
  typename Operator::IteratorB warp_tile_iterator_B_;

public:

  /// Construct from tensor references
  CUTLASS_DEVICE
  MmaBase(
      ///< Shared storage needed for internal use by threadblock-scoped GEMM
      SharedStorage &shared_storage,
      ///< ID within the threadblock
      int thread_idx,
      ///< ID of warp
      int warp_idx,
      ///< ID of each thread within a warp
      int lane_idx
    ):
      warp_tile_iterator_A_(shared_storage.operand_A_ref(), lane_idx),
      warp_tile_iterator_B_(shared_storage.operand_B_ref(), lane_idx) {

  }
};

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

}  // namespace threadblock
}  // namespace gemm
}  // namespace cutlass

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