ceph/src/boost/boost/compute/algorithm/detail/serial_find_extrema.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_DETAIL_SERIAL_FIND_EXTREMA_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_FIND_EXTREMA_HPP
  13
  14 #include <boost/compute/command_queue.hpp>
  15 #include <boost/compute/types/fundamental.hpp>
  16 #include <boost/compute/detail/meta_kernel.hpp>
  17 #include <boost/compute/detail/iterator_range_size.hpp>
  18 #include <boost/compute/container/detail/scalar.hpp>
  19
  20 namespace boost {
  21 namespace compute {
  22 namespace detail {
  23
  24 template<class InputIterator, class Compare>
  25 inline InputIterator serial_find_extrema(InputIterator first,
  26                                          InputIterator last,
  27                                          Compare compare,
  28                                          const bool find_minimum,
  29                                          command_queue &queue)
  30 {
  31     typedef typename std::iterator_traits<InputIterator>::value_type value_type;
  32     typedef typename std::iterator_traits<InputIterator>::difference_type difference_type;
  33
  34     const context &context = queue.get_context();
  35
  36     meta_kernel k("serial_find_extrema");
  37
  38     k <<
  39         k.decl<value_type>("value") << " = " << first[k.expr<uint_>("0")] << ";\n" <<
  40         k.decl<uint_>("value_index") << " = 0;\n" <<
  41         "for(uint i = 1; i < size; i++){\n" <<
  42         "  " << k.decl<value_type>("candidate") << "="
  43              << first[k.expr<uint_>("i")] << ";\n" <<
  44
  45         "#ifndef BOOST_COMPUTE_FIND_MAXIMUM\n" <<
  46         "  if(" << compare(k.var<value_type>("candidate"),
  47                            k.var<value_type>("value")) << "){\n" <<
  48         "#else\n" <<
  49         "  if(" << compare(k.var<value_type>("value"),
  50                            k.var<value_type>("candidate")) << "){\n" <<
  51         "#endif\n" <<
  52
  53         "    value = candidate;\n" <<
  54         "    value_index = i;\n" <<
  55         "  }\n" <<
  56         "}\n" <<
  57         "*index = value_index;\n";
  58
  59     size_t index_arg_index = k.add_arg<uint_ *>(memory_object::global_memory, "index");
  60     size_t size_arg_index = k.add_arg<uint_>("size");
  61
  62     std::string options;
  63     if(!find_minimum){
  64         options = "-DBOOST_COMPUTE_FIND_MAXIMUM";
  65     }
  66     kernel kernel = k.compile(context, options);
  67
  68     // setup index buffer
  69     scalar<uint_> index(context);
  70     kernel.set_arg(index_arg_index, index.get_buffer());
  71
  72     // setup count
  73     size_t count = iterator_range_size(first, last);
  74     kernel.set_arg(size_arg_index, static_cast<uint_>(count));
  75
  76     // run kernel
  77     queue.enqueue_task(kernel);
  78
  79     // read index and return iterator
  80     return first + static_cast<difference_type>(index.read(queue));
  81 }
  82
  83 } // end detail namespace
  84 } // end compute namespace
  85 } // end boost namespace
  86
  87 #endif // BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_FIND_EXTREMA_HPP