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#pragma once

#ifndef OPENCV_CUDEV_BLOCK_REDUCE_DETAIL_HPP
#define OPENCV_CUDEV_BLOCK_REDUCE_DETAIL_HPP

#include "../../common.hpp"
#include "../../util/tuple.hpp"
#include "../../util/type_traits.hpp"
#include "../../warp/warp.hpp"
#include "../../warp/shuffle.hpp"

namespace cv { namespace cudev {

namespace block_reduce_detail
{
    // GetType

    template <typename T> struct GetType;

    template <typename T> struct GetType<T*>
    {
        typedef T type;
    };

    template <typename T> struct GetType<volatile T*>
    {
        typedef T type;
    };

    template <typename T> struct GetType<T&>
    {
        typedef T type;
    };

    // For

    template <int I, int N> struct For
    {
        template <class PointerTuple, class ValTuple>
        __device__ static void loadToSmem(const PointerTuple& smem, const ValTuple& val, uint tid)
        {
            get<I>(smem)[tid] = get<I>(val);

            For<I + 1, N>::loadToSmem(smem, val, tid);
        }

        template <class PointerTuple, class ValTuple>
        __device__ static void loadFromSmem(const PointerTuple& smem, const ValTuple& val, uint tid)
        {
            get<I>(val) = get<I>(smem)[tid];

            For<I + 1, N>::loadFromSmem(smem, val, tid);
        }

        template <class PointerTuple, class ValTuple, class OpTuple>
        __device__ static void merge(const PointerTuple& smem, const ValTuple& val, uint tid, uint delta, const OpTuple& op)
        {
            typename GetType<typename tuple_element<I, PointerTuple>::type>::type reg = get<I>(smem)[tid + delta];
            get<I>(smem)[tid] = get<I>(val) = get<I>(op)(get<I>(val), reg);

            For<I + 1, N>::merge(smem, val, tid, delta, op);
        }

#if CV_CUDEV_ARCH >= 300
        template <class ValTuple, class OpTuple>
        __device__ static void mergeShfl(const ValTuple& val, uint delta, uint width, const OpTuple& op)
        {
            typename GetType<typename tuple_element<I, ValTuple>::type>::type reg = shfl_down(get<I>(val), delta, width);
            get<I>(val) = get<I>(op)(get<I>(val), reg);

            For<I + 1, N>::mergeShfl(val, delta, width, op);
        }
#endif
    };

    template <int N> struct For<N, N>
    {
        template <class PointerTuple, class ValTuple>
        __device__ __forceinline__ static void loadToSmem(const PointerTuple&, const ValTuple&, uint)
        {
        }
        template <class PointerTuple, class ValTuple>
        __device__ __forceinline__ static void loadFromSmem(const PointerTuple&, const ValTuple&, uint)
        {
        }

        template <class PointerTuple, class ValTuple, class OpTuple>
        __device__ __forceinline__ static void merge(const PointerTuple&, const ValTuple&, uint, uint, const OpTuple&)
        {
        }

#if CV_CUDEV_ARCH >= 300
        template <class ValTuple, class OpTuple>
        __device__ __forceinline__ static void mergeShfl(const ValTuple&, uint, uint, const OpTuple&)
        {
        }
#endif
    };

    // loadToSmem / loadFromSmem

    template <typename T>
    __device__ __forceinline__ void loadToSmem(volatile T* smem, T& val, uint tid)
    {
        smem[tid] = val;
    }

    template <typename T>
    __device__ __forceinline__ void loadFromSmem(volatile T* smem, T& val, uint tid)
    {
        val = smem[tid];
    }

    template <typename P0, typename P1, typename P2, typename P3, typename P4, typename P5, typename P6, typename P7, typename P8, typename P9,
              typename R0, typename R1, typename R2, typename R3, typename R4, typename R5, typename R6, typename R7, typename R8, typename R9>
    __device__ __forceinline__ void loadToSmem(const tuple<P0, P1, P2, P3, P4, P5, P6, P7, P8, P9>& smem,
                                               const tuple<R0, R1, R2, R3, R4, R5, R6, R7, R8, R9>& val,
                                               uint tid)
    {
        For<0, tuple_size<tuple<P0, P1, P2, P3, P4, P5, P6, P7, P8, P9> >::value>::loadToSmem(smem, val, tid);
    }

    template <typename P0, typename P1, typename P2, typename P3, typename P4, typename P5, typename P6, typename P7, typename P8, typename P9,
              typename R0, typename R1, typename R2, typename R3, typename R4, typename R5, typename R6, typename R7, typename R8, typename R9>
    __device__ __forceinline__ void loadFromSmem(const tuple<P0, P1, P2, P3, P4, P5, P6, P7, P8, P9>& smem,
                                                     const tuple<R0, R1, R2, R3, R4, R5, R6, R7, R8, R9>& val,
                                                     uint tid)
    {
        For<0, tuple_size<tuple<P0, P1, P2, P3, P4, P5, P6, P7, P8, P9> >::value>::loadFromSmem(smem, val, tid);
    }

    // merge

    template <typename T, class Op>
    __device__ __forceinline__ void merge(volatile T* smem, T& val, uint tid, uint delta, const Op& op)
    {
        T reg = smem[tid + delta];
        smem[tid] = val = op(val, reg);
    }

    template <typename P0, typename P1, typename P2, typename P3, typename P4, typename P5, typename P6, typename P7, typename P8, typename P9,
              typename R0, typename R1, typename R2, typename R3, typename R4, typename R5, typename R6, typename R7, typename R8, typename R9,
              class Op0, class Op1, class Op2, class Op3, class Op4, class Op5, class Op6, class Op7, class Op8, class Op9>
    __device__ __forceinline__ void merge(const tuple<P0, P1, P2, P3, P4, P5, P6, P7, P8, P9>& smem,
                                          const tuple<R0, R1, R2, R3, R4, R5, R6, R7, R8, R9>& val,
                                          uint tid,
                                          uint delta,
                                          const tuple<Op0, Op1, Op2, Op3, Op4, Op5, Op6, Op7, Op8, Op9>& op)
    {
        For<0, tuple_size<tuple<P0, P1, P2, P3, P4, P5, P6, P7, P8, P9> >::value>::merge(smem, val, tid, delta, op);
    }

    // mergeShfl

#if CV_CUDEV_ARCH >= 300
    template <typename T, class Op>
    __device__ __forceinline__ void mergeShfl(T& val, uint delta, uint width, const Op& op)
    {
        T reg = shfl_down(val, delta, width);
        val = op(val, reg);
    }

    template <typename R0, typename R1, typename R2, typename R3, typename R4, typename R5, typename R6, typename R7, typename R8, typename R9,
              class Op0, class Op1, class Op2, class Op3, class Op4, class Op5, class Op6, class Op7, class Op8, class Op9>
    __device__ __forceinline__ void mergeShfl(const tuple<R0, R1, R2, R3, R4, R5, R6, R7, R8, R9>& val,
                                              uint delta,
                                              uint width,
                                              const tuple<Op0, Op1, Op2, Op3, Op4, Op5, Op6, Op7, Op8, Op9>& op)
    {
        For<0, tuple_size<tuple<R0, R1, R2, R3, R4, R5, R6, R7, R8, R9> >::value>::mergeShfl(val, delta, width, op);
    }
#endif

    // Generic

    template <int N> struct Generic
    {
        template <typename Pointer, typename Reference, class Op>
        __device__ static void reduce(Pointer smem, Reference val, uint tid, Op op)
        {
            loadToSmem(smem, val, tid);
            if (N >= 32)
                __syncthreads();

            if (N >= 2048)
            {
                if (tid < 1024)
                    merge(smem, val, tid, 1024, op);

                __syncthreads();
            }
            if (N >= 1024)
            {
                if (tid < 512)
                    merge(smem, val, tid, 512, op);

                __syncthreads();
            }
            if (N >= 512)
            {
                if (tid < 256)
                    merge(smem, val, tid, 256, op);

                __syncthreads();
            }
            if (N >= 256)
            {
                if (tid < 128)
                    merge(smem, val, tid, 128, op);

                __syncthreads();
            }
            if (N >= 128)
            {
                if (tid < 64)
                    merge(smem, val, tid, 64, op);

                __syncthreads();
            }
            if (N >= 64)
            {
                if (tid < 32)
                    merge(smem, val, tid, 32, op);
            }

            if (tid < 16)
            {
                merge(smem, val, tid, 16, op);
                merge(smem, val, tid, 8, op);
                merge(smem, val, tid, 4, op);
                merge(smem, val, tid, 2, op);
                merge(smem, val, tid, 1, op);
            }
        }
    };

    // Unroll

    template <int I, typename Pointer, typename Reference, class Op> struct Unroll
    {
        __device__ static void loop(Pointer smem, Reference val, uint tid, Op op)
        {
            merge(smem, val, tid, I, op);
            Unroll<I / 2, Pointer, Reference, Op>::loop(smem, val, tid, op);
        }

#if CV_CUDEV_ARCH >= 300
        __device__ static void loopShfl(Reference val, Op op, uint N)
        {
            mergeShfl(val, I, N, op);
            Unroll<I / 2, Pointer, Reference, Op>::loopShfl(val, op, N);
        }
#endif
    };

    template <typename Pointer, typename Reference, class Op> struct Unroll<0, Pointer, Reference, Op>
    {
        __device__ __forceinline__ static void loop(Pointer, Reference, uint, Op)
        {
        }

#if CV_CUDEV_ARCH >= 300
        __device__ __forceinline__ static void loopShfl(Reference, Op, uint)
        {
        }
#endif
    };

    // WarpOptimized

    template <int N> struct WarpOptimized
    {
        template <typename Pointer, typename Reference, class Op>
        __device__ static void reduce(Pointer smem, Reference val, uint tid, Op op)
        {
        #if CV_CUDEV_ARCH >= 300
            CV_UNUSED(smem);
            CV_UNUSED(tid);

            Unroll<N / 2, Pointer, Reference, Op>::loopShfl(val, op, N);
        #else
            loadToSmem(smem, val, tid);

            if (tid < N / 2)
                Unroll<N / 2, Pointer, Reference, Op>::loop(smem, val, tid, op);
        #endif
        }
    };

    // GenericOptimized32

    template <int N> struct GenericOptimized32
    {
        enum { M = N / 32 };

        template <typename Pointer, typename Reference, class Op>
        __device__ static void reduce(Pointer smem, Reference val, uint tid, Op op)
        {
            const uint laneId = Warp::laneId();

        #if CV_CUDEV_ARCH >= 300
            Unroll<16, Pointer, Reference, Op>::loopShfl(val, op, warpSize);

            if (laneId == 0)
                loadToSmem(smem, val, tid / 32);
        #else
            loadToSmem(smem, val, tid);

            if (laneId < 16)
                Unroll<16, Pointer, Reference, Op>::loop(smem, val, tid, op);

            __syncthreads();

            if (laneId == 0)
                loadToSmem(smem, val, tid / 32);
        #endif

            __syncthreads();

            loadFromSmem(smem, val, tid);

            if (tid < 32)
            {
        #if CV_CUDEV_ARCH >= 300
                Unroll<M / 2, Pointer, Reference, Op>::loopShfl(val, op, M);
        #else
                Unroll<M / 2, Pointer, Reference, Op>::loop(smem, val, tid, op);
        #endif
            }
        }
    };

    template <int N> struct Dispatcher
    {
        typedef typename SelectIf<
            (N <= 32) && IsPowerOf2<N>::value,
            WarpOptimized<N>,
            typename SelectIf<
                (N <= 1024) && IsPowerOf2<N>::value,
                GenericOptimized32<N>,
                Generic<N>
            >::type
        >::type reductor;
    };
}

}}

#endif
