ceph/src/boost/libs/compute/include/boost/compute/algorithm/detail/count_if_with_ballot.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_COUNT_IF_WITH_BALLOT_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_DETAIL_COUNT_IF_WITH_BALLOT_HPP
  13
  14 #include <boost/compute/context.hpp>
  15 #include <boost/compute/command_queue.hpp>
  16 #include <boost/compute/container/vector.hpp>
  17 #include <boost/compute/algorithm/reduce.hpp>
  18 #include <boost/compute/functional/detail/nvidia_ballot.hpp>
  19 #include <boost/compute/functional/detail/nvidia_popcount.hpp>
  20 #include <boost/compute/detail/meta_kernel.hpp>
  21
  22 namespace boost {
  23 namespace compute {
  24 namespace detail {
  25
  26 template<class InputIterator, class Predicate>
  27 inline size_t count_if_with_ballot(InputIterator first,
  28                                    InputIterator last,
  29                                    Predicate predicate,
  30                                    command_queue &queue)
  31 {
  32     size_t count = iterator_range_size(first, last);
  33     size_t block_size = 32;
  34     size_t block_count = count / block_size;
  35     if(block_count * block_size != count){
  36         block_count++;
  37     }
  38
  39     const ::boost::compute::context &context = queue.get_context();
  40
  41     ::boost::compute::vector<uint_> counts(block_count, context);
  42
  43     ::boost::compute::detail::nvidia_popcount<uint_> popc;
  44     ::boost::compute::detail::nvidia_ballot<uint_> ballot;
  45
  46     meta_kernel k("count_if_with_ballot");
  47     k <<
  48         "const uint gid = get_global_id(0);\n" <<
  49
  50         "bool value = false;\n" <<
  51         "if(gid < count)\n" <<
  52         "    value = " << predicate(first[k.var<const uint_>("gid")]) << ";\n" <<
  53
  54         "uint bits = " << ballot(k.var<const uint_>("value")) << ";\n" <<
  55
  56         "if(get_local_id(0) == 0)\n" <<
  57             counts.begin()[k.var<uint_>("get_group_id(0)") ]
  58                 << " = " << popc(k.var<uint_>("bits")) << ";\n";
  59
  60     k.add_set_arg<const uint_>("count", count);
  61
  62     k.exec_1d(queue, 0, block_size * block_count, block_size);
  63
  64     uint_ result;
  65     ::boost::compute::reduce(
  66         counts.begin(),
  67         counts.end(),
  68         &result,
  69         queue
  70     );
  71     return result;
  72 }
  73
  74 } // end detail namespace
  75 } // end compute namespace
  76 } // end boost namespace
  77
  78 #endif // BOOST_COMPUTE_ALGORITHM_DETAIL_COUNT_IF_WITH_BALLOT_HPP