ceph/src/boost/libs/compute/include/boost/compute/algorithm/gather.hpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 // See http://boostorg.github.com/compute for more information.
   9 //---------------------------------------------------------------------------//
  10
  11 #ifndef BOOST_COMPUTE_ALGORITHM_GATHER_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_GATHER_HPP
  13
  14 #include <boost/compute/command_queue.hpp>
  15 #include <boost/compute/detail/iterator_range_size.hpp>
  16 #include <boost/compute/detail/meta_kernel.hpp>
  17 #include <boost/compute/exception.hpp>
  18 #include <boost/compute/iterator/buffer_iterator.hpp>
  19 #include <boost/compute/system.hpp>
  20 #include <boost/compute/type_traits/type_name.hpp>
  21
  22 namespace boost {
  23 namespace compute {
  24 namespace detail {
  25
  26 template<class InputIterator, class MapIterator, class OutputIterator>
  27 class gather_kernel : public meta_kernel
  28 {
  29 public:
  30     gather_kernel() : meta_kernel("gather")
  31     {}
  32
  33     void set_range(MapIterator first,
  34                    MapIterator last,
  35                    InputIterator input,
  36                    OutputIterator result)
  37     {
  38         m_count = iterator_range_size(first, last);
  39
  40         *this <<
  41             "const uint i = get_global_id(0);\n" <<
  42             result[expr<uint_>("i")] << "=" <<
  43                 input[first[expr<uint_>("i")]] << ";\n";
  44     }
  45
  46     event exec(command_queue &queue)
  47     {
  48         if(m_count == 0) {
  49             return event();
  50         }
  51
  52         return exec_1d(queue, 0, m_count);
  53     }
  54
  55 private:
  56     size_t m_count;
  57 };
  58
  59 } // end detail namespace
  60
  61 /// Copies the elements using the indices from the range [\p first, \p last)
  62 /// to the range beginning at \p result using the input values from the range
  63 /// beginning at \p input.
  64 ///
  65 /// \see scatter()
  66 template<class InputIterator, class MapIterator, class OutputIterator>
  67 inline void gather(MapIterator first,
  68                    MapIterator last,
  69                    InputIterator input,
  70                    OutputIterator result,
  71                    command_queue &queue = system::default_queue())
  72 {
  73     detail::gather_kernel<InputIterator, MapIterator, OutputIterator> kernel;
  74
  75     kernel.set_range(first, last, input, result);
  76     kernel.exec(queue);
  77 }
  78
  79 } // end compute namespace
  80 } // end boost namespace
  81
  82 #endif // BOOST_COMPUTE_ALGORITHM_GATHER_HPP