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/*! \file
    \brief Reference implementation for GEMM in host-side code.
*/
#pragma once

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

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

namespace cutlass {
namespace reference {
namespace detail {

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

template <int Rank, int Index>
struct LinearToCoordinateHelper {
    CUTLASS_HOST_DEVICE
    void operator()(Coord<Rank>& coord, int64_t idx,
                    Coord<Rank> const& extent) const {
        int64_t prod = 1;

        CUTLASS_PRAGMA_UNROLL
        for (int i = Rank - Index; i < Rank; ++i) {
            prod *= int64_t(extent[i]);
        }

        coord[Rank - Index - 1] = int(idx / prod);

        int64_t residual = idx % prod;
        LinearToCoordinateHelper<Rank, Index - 1>()(coord, residual, extent);
    }
};

template <int Rank>
struct LinearToCoordinateHelper<Rank, 0> {
    CUTLASS_HOST_DEVICE
    void operator()(Coord<Rank>& coord, int64_t idx,
                    Coord<Rank> const& extent) const {
        coord[Rank - 1] = int(idx);
    }
};

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

template <int Rank>
struct LinearToCoordinate {
    CUTLASS_HOST_DEVICE
    void operator()(Coord<Rank>& coord, int64_t idx,
                    Coord<Rank> const& extent) const {
        LinearToCoordinateHelper<Rank, Rank - 1>()(coord, idx, extent);
    }
};

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

}  // namespace detail
}  // namespace reference
}  // namespace cutlass

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