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/*! \file
    \brief Implements the BLAS linear scaling function alpha*AB + beta*C
*/
#pragma once

#include <cutlass/fragment_multiply_add.h>

namespace cutlass {
namespace gemm {

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

/// Functor to compute linear combination of fragments
template <typename Scalar_, typename FragmentMultiplyAdd_ = FragmentMultiplyAdd<Scalar_> >
struct LinearScaling {
  // The scalar.
  typedef Scalar_ Scalar;
  // The adapater.
  typedef FragmentMultiplyAdd_ FragmentMultiplyAdd;

  /// The parameters.
  struct Params {
    /// The alpha/beta scaling params.
    Scalar alpha, beta;

    /// Initialize the parameters.
    template <typename GemmDesc_>
    CUTLASS_HOST_DEVICE int initialize(GemmDesc_ const& desc) {
      alpha = desc.alpha;
      beta = desc.beta;
      return 0;
    }
  };

  /// Ctor.
  CUTLASS_DEVICE LinearScaling(Params const& params) : alpha(params.alpha), beta(params.beta) {}

  /// Evaluate the functor.
  template <typename Fragment_>
  CUTLASS_DEVICE void evaluate(Fragment_ const& accum, Fragment_& output) {
    FragmentMultiplyAdd mad;
    mad.multiply(alpha, accum, output);
  }

  /// Evaluate the functor.
  template <typename Fragment_>
  CUTLASS_DEVICE void evaluate(Fragment_ const& accum, Fragment_ const& old, Fragment_& output) {
    FragmentMultiplyAdd mad;
    Fragment_ tmp;
    mad.multiply(beta, old, tmp);
    mad.multiply_add(alpha, accum, tmp, output);
  }

  /// The alpha/beta scaling factors.
  Scalar alpha, beta;
};

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

}  // namespace gemm
}  // namespace cutlass
