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_SCATTER_HPP
12 #define BOOST_COMPUTE_ALGORITHM_SCATTER_HPP
13
14 #include <boost/static_assert.hpp>
15 #include <boost/algorithm/string/replace.hpp>
16
17 #include <boost/compute/system.hpp>
18 #include <boost/compute/exception.hpp>
19 #include <boost/compute/command_queue.hpp>
20 #include <boost/compute/iterator/buffer_iterator.hpp>
21 #include <boost/compute/type_traits/type_name.hpp>
22 #include <boost/compute/detail/iterator_range_size.hpp>
23 #include <boost/compute/detail/meta_kernel.hpp>
24 #include <boost/compute/type_traits/is_device_iterator.hpp>
25
26 namespace boost {
27 namespace compute {
28 namespace detail {
29
30 template<class InputIterator, class MapIterator, class OutputIterator>
31 class scatter_kernel : meta_kernel
32 {
33 public:
scatter_kernel()34 scatter_kernel() : meta_kernel("scatter")
35 {}
36
set_range(InputIterator first,InputIterator last,MapIterator map,OutputIterator result)37 void set_range(InputIterator first,
38 InputIterator last,
39 MapIterator map,
40 OutputIterator result)
41 {
42 m_count = iterator_range_size(first, last);
43 m_input_offset = first.get_index();
44 m_output_offset = result.get_index();
45
46 m_input_offset_arg = add_arg<uint_>("input_offset");
47 m_output_offset_arg = add_arg<uint_>("output_offset");
48
49 *this <<
50 "const uint i = get_global_id(0);\n" <<
51 "uint i1 = " << map[expr<uint_>("i")] <<
52 " + output_offset;\n" <<
53 "uint i2 = i + input_offset;\n" <<
54 result[expr<uint_>("i1")] << "=" <<
55 first[expr<uint_>("i2")] << ";\n";
56 }
57
exec(command_queue & queue)58 event exec(command_queue &queue)
59 {
60 if(m_count == 0) {
61 return event();
62 }
63
64 set_arg(m_input_offset_arg, uint_(m_input_offset));
65 set_arg(m_output_offset_arg, uint_(m_output_offset));
66
67 return exec_1d(queue, 0, m_count);
68 }
69
70 private:
71 size_t m_count;
72 size_t m_input_offset;
73 size_t m_input_offset_arg;
74 size_t m_output_offset;
75 size_t m_output_offset_arg;
76 };
77
78 } // end detail namespace
79
80 /// Copies the elements from the range [\p first, \p last) to the range
81 /// beginning at \p result using the output indices from the range beginning
82 /// at \p map.
83 ///
84 /// Space complexity: \Omega(1)
85 ///
86 /// \see gather()
87 template<class InputIterator, class MapIterator, class OutputIterator>
scatter(InputIterator first,InputIterator last,MapIterator map,OutputIterator result,command_queue & queue=system::default_queue ())88 inline void scatter(InputIterator first,
89 InputIterator last,
90 MapIterator map,
91 OutputIterator result,
92 command_queue &queue = system::default_queue())
93 {
94 BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
95 BOOST_STATIC_ASSERT(is_device_iterator<MapIterator>::value);
96 BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
97
98 detail::scatter_kernel<InputIterator, MapIterator, OutputIterator> kernel;
99
100 kernel.set_range(first, last, map, result);
101 kernel.exec(queue);
102 }
103
104 } // end compute namespace
105 } // end boost namespace
106
107 #endif // BOOST_COMPUTE_ALGORITHM_SCATTER_HPP
108