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  /**
   * \file
   * cub::BlockReduceRakingCommutativeOnly provides raking-based methods of parallel reduction across a CUDA thread block.  Does not support non-commutative reduction operators.
   */
  
  #pragma once
  
  #include "block_reduce_raking.cuh"
  #include "../../warp/warp_reduce.cuh"
  #include "../../thread/thread_reduce.cuh"
  #include "../../util_ptx.cuh"
  #include "../../util_namespace.cuh"
  
  /// Optional outer namespace(s)
  CUB_NS_PREFIX
  
  /// CUB namespace
  namespace cub {
  
  
  /**
   * \brief BlockReduceRakingCommutativeOnly provides raking-based methods of parallel reduction across a CUDA thread block.  Does not support non-commutative reduction operators.  Does not support block sizes that are not a multiple of the warp size.
   */
  template <
      typename    T,              ///< Data type being reduced
      int         BLOCK_DIM_X,    ///< The thread block length in threads along the X dimension
      int         BLOCK_DIM_Y,    ///< The thread block length in threads along the Y dimension
      int         BLOCK_DIM_Z,    ///< The thread block length in threads along the Z dimension
      int         PTX_ARCH>       ///< The PTX compute capability for which to to specialize this collective
  struct BlockReduceRakingCommutativeOnly
  {
      /// Constants
      enum
      {
          /// The thread block size in threads
          BLOCK_THREADS = BLOCK_DIM_X * BLOCK_DIM_Y * BLOCK_DIM_Z,
      };
  
      // The fall-back implementation to use when BLOCK_THREADS is not a multiple of the warp size or not all threads have valid values
      typedef BlockReduceRaking<T, BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH> FallBack;
  
      /// Constants
      enum
      {
          /// Number of warp threads
          WARP_THREADS = CUB_WARP_THREADS(PTX_ARCH),
  
          /// Whether or not to use fall-back
          USE_FALLBACK = ((BLOCK_THREADS % WARP_THREADS != 0) || (BLOCK_THREADS <= WARP_THREADS)),
  
          /// Number of raking threads
          RAKING_THREADS = WARP_THREADS,
  
          /// Number of threads actually sharing items with the raking threads
          SHARING_THREADS = CUB_MAX(1, BLOCK_THREADS - RAKING_THREADS),
  
          /// Number of raking elements per warp synchronous raking thread
          SEGMENT_LENGTH = SHARING_THREADS / WARP_THREADS,
      };
  
      ///  WarpReduce utility type
      typedef WarpReduce<T, RAKING_THREADS, PTX_ARCH> WarpReduce;
  
      /// Layout type for padded thread block raking grid
      typedef BlockRakingLayout<T, SHARING_THREADS, PTX_ARCH> BlockRakingLayout;
  
      /// Shared memory storage layout type
      union _TempStorage
      {
          struct
          {
              typename WarpReduce::TempStorage        warp_storage;        ///< Storage for warp-synchronous reduction
              typename BlockRakingLayout::TempStorage raking_grid;         ///< Padded thread block raking grid
          };
          typename FallBack::TempStorage              fallback_storage;    ///< Fall-back storage for non-commutative block scan
      };
  
  
      /// Alias wrapper allowing storage to be unioned
      struct TempStorage : Uninitialized<_TempStorage> {};
  
  
      // Thread fields
      _TempStorage &temp_storage;
      unsigned int linear_tid;
  
  
      /// Constructor
      __device__ __forceinline__ BlockReduceRakingCommutativeOnly(
          TempStorage &temp_storage)
      :
          temp_storage(temp_storage.Alias()),
          linear_tid(RowMajorTid(BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z))
      {}
  
  
      /// Computes a thread block-wide reduction using addition (+) as the reduction operator. The first num_valid threads each contribute one reduction partial.  The return value is only valid for thread<sub>0</sub>.
      template <bool FULL_TILE>
      __device__ __forceinline__ T Sum(
          T                   partial,            ///< [in] Calling thread's input partial reductions
          int                 num_valid)          ///< [in] Number of valid elements (may be less than BLOCK_THREADS)
      {
          if (USE_FALLBACK || !FULL_TILE)
          {
              return FallBack(temp_storage.fallback_storage).template Sum<FULL_TILE>(partial, num_valid);
          }
          else
          {
              // Place partial into shared memory grid
              if (linear_tid >= RAKING_THREADS)
                  *BlockRakingLayout::PlacementPtr(temp_storage.raking_grid, linear_tid - RAKING_THREADS) = partial;
  
              CTA_SYNC();
  
              // Reduce parallelism to one warp
              if (linear_tid < RAKING_THREADS)
              {
                  // Raking reduction in grid
                  T *raking_segment = BlockRakingLayout::RakingPtr(temp_storage.raking_grid, linear_tid);
                  partial = internal::ThreadReduce<SEGMENT_LENGTH>(raking_segment, cub::Sum(), partial);
  
                  // Warpscan
                  partial = WarpReduce(temp_storage.warp_storage).Sum(partial);
              }
          }
  
          return partial;
      }
  
  
      /// Computes a thread block-wide reduction using the specified reduction operator. The first num_valid threads each contribute one reduction partial.  The return value is only valid for thread<sub>0</sub>.
      template <
          bool                FULL_TILE,
          typename            ReductionOp>
      __device__ __forceinline__ T Reduce(
          T                   partial,            ///< [in] Calling thread's input partial reductions
          int                 num_valid,          ///< [in] Number of valid elements (may be less than BLOCK_THREADS)
          ReductionOp         reduction_op)       ///< [in] Binary reduction operator
      {
          if (USE_FALLBACK || !FULL_TILE)
          {
              return FallBack(temp_storage.fallback_storage).template Reduce<FULL_TILE>(partial, num_valid, reduction_op);
          }
          else
          {
              // Place partial into shared memory grid
              if (linear_tid >= RAKING_THREADS)
                  *BlockRakingLayout::PlacementPtr(temp_storage.raking_grid, linear_tid - RAKING_THREADS) = partial;
  
              CTA_SYNC();
  
              // Reduce parallelism to one warp
              if (linear_tid < RAKING_THREADS)
              {
                  // Raking reduction in grid
                  T *raking_segment = BlockRakingLayout::RakingPtr(temp_storage.raking_grid, linear_tid);
                  partial = internal::ThreadReduce<SEGMENT_LENGTH>(raking_segment, reduction_op, partial);
  
                  // Warpscan
                  partial = WarpReduce(temp_storage.warp_storage).Reduce(partial, reduction_op);
              }
          }
  
          return partial;
      }
  
  };
  
  }               // CUB namespace
  CUB_NS_POSTFIX  // Optional outer namespace(s)