compute/algorithm/scatter_if.hpp

0001 //---------------------------------------------------------------------------//
0002 // Copyright (c) 2015 Jakub Pola <jakub.pola@gmail.com>
0003 //
0004 // Distributed under the Boost Software License, Version 1.0
0005 // See accompanying file LICENSE_1_0.txt or copy at
0006 // http://www.boost.org/LICENSE_1_0.txt
0007 //
0008 // See http://boostorg.github.com/compute for more information.
0009 //---------------------------------------------------------------------------//
0010
0011 #ifndef BOOST_COMPUTE_ALGORITHM_SCATTER_IF_HPP
0012 #define BOOST_COMPUTE_ALGORITHM_SCATTER_IF_HPP
0013
0014 #include <boost/static_assert.hpp>
0015 #include <boost/algorithm/string/replace.hpp>
0016
0017 #include <boost/compute/system.hpp>
0018 #include <boost/compute/exception.hpp>
0019 #include <boost/compute/command_queue.hpp>
0020 #include <boost/compute/iterator/buffer_iterator.hpp>
0021 #include <boost/compute/type_traits/type_name.hpp>
0022 #include <boost/compute/detail/iterator_range_size.hpp>
0023 #include <boost/compute/detail/meta_kernel.hpp>
0024 #include <boost/compute/type_traits/is_device_iterator.hpp>
0025
0026 namespace boost {
0027 namespace compute {
0028 namespace detail {
0029
0030 template<class InputIterator, class MapIterator, class StencilIterator, class OutputIterator, class Predicate>
0031 class scatter_if_kernel : meta_kernel
0032 {
0033 public:
0034     scatter_if_kernel() : meta_kernel("scatter_if")
0035     {}
0036
0037     void set_range(InputIterator first,
0038                    InputIterator last,
0039                    MapIterator map,
0040                    StencilIterator stencil,
0041                    OutputIterator result,
0042                    Predicate predicate)
0043     {
0044         m_count = iterator_range_size(first, last);
0045         m_input_offset = first.get_index();
0046         m_output_offset = result.get_index();
0047
0048         m_input_offset_arg = add_arg<uint_>("input_offset");
0049         m_output_offset_arg = add_arg<uint_>("output_offset");
0050
0051         *this <<
0052         "const uint i = get_global_id(0);\n" <<
0053         "uint i1 = " << map[expr<uint_>("i")] <<
0054         " + output_offset;\n" <<
0055         "uint i2 = i + input_offset;\n" <<
0056         if_(predicate(stencil[expr<uint_>("i")])) << "\n" <<
0057             result[expr<uint_>("i1")] << "=" <<
0058             first[expr<uint_>("i2")] << ";\n";
0059     }
0060
0061     event exec(command_queue &queue)
0062     {
0063         if(m_count == 0) {
0064             return event();
0065         }
0066
0067         set_arg(m_input_offset_arg, uint_(m_input_offset));
0068         set_arg(m_output_offset_arg, uint_(m_output_offset));
0069
0070         return exec_1d(queue, 0, m_count);
0071     }
0072
0073 private:
0074     size_t m_count;
0075     size_t m_input_offset;
0076     size_t m_input_offset_arg;
0077     size_t m_output_offset;
0078     size_t m_output_offset_arg;
0079 };
0080
0081 } // end detail namespace
0082
0083 /// Copies the elements from the range [\p first, \p last) to the range
0084 /// beginning at \p result using the output indices from the range beginning
0085 /// at \p map if stencil is resolved to true. By default the predicate is
0086 /// an identity
0087 ///
0088 /// Space complexity: \Omega(1)
0089 template<class InputIterator, class MapIterator, class StencilIterator, class OutputIterator,
0090          class Predicate>
0091 inline void scatter_if(InputIterator first,
0092                        InputIterator last,
0093                        MapIterator map,
0094                        StencilIterator stencil,
0095                        OutputIterator result,
0096                        Predicate predicate,
0097                        command_queue &queue = system::default_queue())
0098 {
0099     BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
0100     BOOST_STATIC_ASSERT(is_device_iterator<MapIterator>::value);
0101     BOOST_STATIC_ASSERT(is_device_iterator<StencilIterator>::value);
0102     BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
0103
0104     detail::scatter_if_kernel<InputIterator, MapIterator, StencilIterator, OutputIterator, Predicate> kernel;
0105
0106     kernel.set_range(first, last, map, stencil, result, predicate);
0107     kernel.exec(queue);
0108 }
0109
0110 template<class InputIterator, class MapIterator, class StencilIterator, class OutputIterator>
0111 inline void scatter_if(InputIterator first,
0112                        InputIterator last,
0113                        MapIterator map,
0114                        StencilIterator stencil,
0115                        OutputIterator result,
0116                        command_queue &queue = system::default_queue())
0117 {
0118     BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
0119     BOOST_STATIC_ASSERT(is_device_iterator<MapIterator>::value);
0120     BOOST_STATIC_ASSERT(is_device_iterator<StencilIterator>::value);
0121     BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
0122
0123     typedef typename std::iterator_traits<StencilIterator>::value_type T;
0124
0125     scatter_if(first, last, map, stencil, result, identity<T>(), queue);
0126 }
0127
0128 } // end compute namespace
0129 } // end boost namespace
0130
0131 #endif // BOOST_COMPUTE_ALGORITHM_SCATTER_IF_HPP