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   * Copyright (c) 2010-2011, Duane Merrill.  All rights reserved.
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  #ifndef ROCPRIM_THREAD_THREAD_REDUCE_HPP_
  #define ROCPRIM_THREAD_THREAD_REDUCE_HPP_
  
  
  #include "../config.hpp"
  
  BEGIN_ROCPRIM_NAMESPACE
  
  /// \brief Carry out a reduction on an array of elements in one thread
  /// \tparam LENGTH - Length of the array to be reduced
  /// \tparam T - the input/output type
  /// \tparam ReductionOp - Binary Operation that used to carry out the reduction
  /// \tparam NoPrefix - Boolean, determining whether to have a initialization value for the reduction accumulator
  /// \param input [in] - Pointer to the first element of the array to be reduced
  /// \param reduction_op [in] - Instance of the reduction operator functor
  /// \param prefix [in] - Value to be used as prefix, if NoPrefix is false
  /// \return - Value obtained from reduction of input array
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp,
      bool        NoPrefix = false>
  ROCPRIM_DEVICE ROCPRIM_INLINE T thread_reduce(
      T*           input,
      ReductionOp reduction_op,
      T           prefix = T(0))
  {
      T retval;
      if(NoPrefix)
          retval = input[0];
      else
          retval = prefix;
  
      ROCPRIM_UNROLL
      for (int i = 0 + NoPrefix; i < LENGTH; ++i)
          retval = reduction_op(retval, input[i]);
  
      return retval;
  }
  
  /// \brief Carry out a reduction on an array of elements in one thread
  /// \tparam LENGTH - Length of the array to be reduced
  /// \tparam T - the input/output type
  /// \tparam ReductionOp - Binary Operation that used to carry out the reduction
  /// \param input [in] - Pointer to the first element of the array to be reduced
  /// \param reduction_op [in] - Instance of the reduction operator functor
  /// \param prefix [in] - Value to be used as prefix
  /// \return - Value obtained from reduction of input array
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp>
  ROCPRIM_DEVICE ROCPRIM_INLINE T thread_reduce(
      T           (&input)[LENGTH],
      ReductionOp reduction_op,
      T           prefix)
  {
      return thread_reduce<LENGTH, false>((T*)input, reduction_op, prefix);
  }
  
  /// \brief Carry out a reduction on an array of elements in one thread
  /// \tparam LENGTH - Length of the array to be reduced
  /// \tparam T - the input/output type
  /// \tparam ReductionOp - Binary Operation that used to carry out the reduction
  /// \param input [in] - Pointer to the first element of the array to be reduced
  /// \param reduction_op [in] - Instance of the reduction operator functor
  /// \return - Value obtained from reduction of input array
  template <
      int         LENGTH,
      typename    T,
      typename    ReductionOp>
  ROCPRIM_DEVICE ROCPRIM_INLINE T thread_reduce(
      T           (&input)[LENGTH],
      ReductionOp reduction_op)
  {
      return thread_reduce<LENGTH, true>((T*)input, reduction_op);
  }
  
  END_ROCPRIM_NAMESPACE
  
  #endif
  