ceph/src/boost/boost/compute/algorithm/detail/serial_scan.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_SCAN_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_SCAN_HPP
  13
  14 #include <iterator>
  15
  16 #include <boost/compute/device.hpp>
  17 #include <boost/compute/kernel.hpp>
  18 #include <boost/compute/command_queue.hpp>
  19 #include <boost/compute/detail/meta_kernel.hpp>
  20 #include <boost/compute/detail/iterator_range_size.hpp>
  21
  22 namespace boost {
  23 namespace compute {
  24 namespace detail {
  25
  26 template<class InputIterator, class OutputIterator, class T, class BinaryOperator>
  27 inline OutputIterator serial_scan(InputIterator first,
  28                                   InputIterator last,
  29                                   OutputIterator result,
  30                                   bool exclusive,
  31                                   T init,
  32                                   BinaryOperator op,
  33                                   command_queue &queue)
  34 {
  35     if(first == last){
  36         return result;
  37     }
  38
  39     typedef typename
  40         std::iterator_traits<InputIterator>::value_type input_type;
  41     typedef typename
  42         std::iterator_traits<OutputIterator>::value_type output_type;
  43
  44     const context &context = queue.get_context();
  45
  46     // create scan kernel
  47     meta_kernel k("serial_scan");
  48
  49     // Arguments
  50     size_t n_arg = k.add_arg<ulong_>("n");
  51     size_t init_arg = k.add_arg<output_type>("initial_value");
  52
  53     if(!exclusive){
  54         k <<
  55             k.decl<const ulong_>("start_idx") << " = 1;\n" <<
  56             k.decl<output_type>("sum") << " = " << first[0] << ";\n" <<
  57             result[0] << " = sum;\n";
  58     }
  59     else {
  60         k <<
  61             k.decl<const ulong_>("start_idx") << " = 0;\n" <<
  62             k.decl<output_type>("sum") << " = initial_value;\n";
  63     }
  64
  65     k <<
  66         "for(ulong i = start_idx; i < n; i++){\n" <<
  67         k.decl<const input_type>("x") << " = "
  68             << first[k.var<ulong_>("i")] << ";\n";
  69
  70     if(exclusive){
  71         k << result[k.var<ulong_>("i")] << " = sum;\n";
  72     }
  73
  74     k << "    sum = "
  75         << op(k.var<output_type>("sum"), k.var<output_type>("x"))
  76         << ";\n";
  77
  78     if(!exclusive){
  79         k << result[k.var<ulong_>("i")] << " = sum;\n";
  80     }
  81
  82     k << "}\n";
  83
  84     // compile scan kernel
  85     kernel scan_kernel = k.compile(context);
  86
  87     // setup kernel arguments
  88     size_t n = detail::iterator_range_size(first, last);
  89     scan_kernel.set_arg<ulong_>(n_arg, n);
  90     scan_kernel.set_arg<output_type>(init_arg, static_cast<output_type>(init));
  91
  92     // execute the kernel
  93     queue.enqueue_1d_range_kernel(scan_kernel, 0, 1, 1);
  94
  95     // return iterator pointing to the end of the result range
  96     return result + n;
  97 }
  98
  99 } // end detail namespace
 100 } // end compute namespace
 101 } // end boost namespace
 102
 103 #endif // BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_SCAN_HPP