text: /******************************************************************************
   * Copyright (c) 2011, Duane Merrill.  All rights reserved.
   * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
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   ******************************************************************************/
  
  /**
   * \file
   * Thread utilities for sequential reduction over statically-sized array types
   */
  
  #pragma once
  
  #include "3rdparty/cub/thread/thread_operators.cuh.h"
  #include "3rdparty/cub/config.cuh.h"
  
  /// Optional outer namespace(s)
  CUB_NS_PREFIX
  
  /// CUB namespace
  namespace cub {
  
  /// Internal namespace (to prevent ADL mishaps between static functions when mixing different CUB installations)
  namespace internal {
  
  /**
   * Sequential reduction over statically-sized array types
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp>
  __device__ __forceinline__ T ThreadReduce(
      T*                  input,                  ///< [in] Input array
      ReductionOp         reduction_op,           ///< [in] Binary reduction operator
      T                   prefix,                 ///< [in] Prefix to seed reduction with
      Int2Type<LENGTH>    /*length*/)
  {
      T retval = prefix;
  
      #pragma unroll
      for (int i = 0; i < LENGTH; ++i)
          retval = reduction_op(retval, input[i]);
  
      return retval;
  }
  
  
  /**
   * \brief Perform a sequential reduction over \p LENGTH elements of the \p input array, seeded with the specified \p prefix.  The aggregate is returned.
   *
   * \tparam LENGTH     LengthT of input array
   * \tparam T          <b>[inferred]</b> The data type to be reduced.
   * \tparam ScanOp     <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp>
  __device__ __forceinline__ T ThreadReduce(
      T*          input,                  ///< [in] Input array
      ReductionOp reduction_op,           ///< [in] Binary reduction operator
      T           prefix)                 ///< [in] Prefix to seed reduction with
  {
      return ThreadReduce(input, reduction_op, prefix, Int2Type<LENGTH>());
  }
  
  
  /**
   * \brief Perform a sequential reduction over \p LENGTH elements of the \p input array.  The aggregate is returned.
   *
   * \tparam LENGTH     LengthT of input array
   * \tparam T          <b>[inferred]</b> The data type to be reduced.
   * \tparam ScanOp     <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp>
  __device__ __forceinline__ T ThreadReduce(
      T*          input,                  ///< [in] Input array
      ReductionOp reduction_op)           ///< [in] Binary reduction operator
  {
      T prefix = input[0];
      return ThreadReduce<LENGTH - 1>(input + 1, reduction_op, prefix);
  }
  
  
  /**
   * \brief Perform a sequential reduction over the statically-sized \p input array, seeded with the specified \p prefix.  The aggregate is returned.
   *
   * \tparam LENGTH     <b>[inferred]</b> LengthT of \p input array
   * \tparam T          <b>[inferred]</b> The data type to be reduced.
   * \tparam ScanOp     <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp>
  __device__ __forceinline__ T ThreadReduce(
      T           (&input)[LENGTH],       ///< [in] Input array
      ReductionOp reduction_op,           ///< [in] Binary reduction operator
      T           prefix)                 ///< [in] Prefix to seed reduction with
  {
      return ThreadReduce(input, reduction_op, prefix, Int2Type<LENGTH>());
  }
  
  
  /**
   * \brief Serial reduction with the specified operator
   *
   * \tparam LENGTH     <b>[inferred]</b> LengthT of \p input array
   * \tparam T          <b>[inferred]</b> The data type to be reduced.
   * \tparam ScanOp     <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp>
  __device__ __forceinline__ T ThreadReduce(
      T           (&input)[LENGTH],       ///< [in] Input array
      ReductionOp reduction_op)           ///< [in] Binary reduction operator
  {
      return ThreadReduce<LENGTH>((T*) input, reduction_op);
  }
  
  
  }               // internal namespace
  }               // CUB namespace
  CUB_NS_POSTFIX  // Optional outer namespace(s)
  