//---------------------------------------------------------------------------//
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// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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// See http://boostorg.github.com/compute for more information.
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//---------------------------------------------------------------------------//
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#ifndef BOOST_COMPUTE_ALGORITHM_SCATTER_HPP
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#define BOOST_COMPUTE_ALGORITHM_SCATTER_HPP
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#include <boost/static_assert.hpp>
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#include <boost/algorithm/string/replace.hpp>
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#include <boost/compute/system.hpp>
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#include <boost/compute/exception.hpp>
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#include <boost/compute/command_queue.hpp>
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#include <boost/compute/iterator/buffer_iterator.hpp>
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#include <boost/compute/type_traits/type_name.hpp>
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#include <boost/compute/detail/iterator_range_size.hpp>
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#include <boost/compute/detail/meta_kernel.hpp>
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#include <boost/compute/type_traits/is_device_iterator.hpp>
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namespace boost {
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namespace compute {
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namespace detail {
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template<class InputIterator, class MapIterator, class OutputIterator>
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class scatter_kernel : meta_kernel
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{
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public:
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scatter_kernel() : meta_kernel("scatter")
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{}
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void set_range(InputIterator first,
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InputIterator last,
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MapIterator map,
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OutputIterator result)
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{
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m_count = iterator_range_size(first, last);
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m_input_offset = first.get_index();
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m_output_offset = result.get_index();
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m_input_offset_arg = add_arg<uint_>("input_offset");
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m_output_offset_arg = add_arg<uint_>("output_offset");
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*this <<
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"const uint i = get_global_id(0);\n" <<
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"uint i1 = " << map[expr<uint_>("i")] <<
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" + output_offset;\n" <<
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"uint i2 = i + input_offset;\n" <<
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result[expr<uint_>("i1")] << "=" <<
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first[expr<uint_>("i2")] << ";\n";
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}
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event exec(command_queue &queue)
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{
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if(m_count == 0) {
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return event();
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}
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set_arg(m_input_offset_arg, uint_(m_input_offset));
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set_arg(m_output_offset_arg, uint_(m_output_offset));
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return exec_1d(queue, 0, m_count);
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}
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private:
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size_t m_count;
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size_t m_input_offset;
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size_t m_input_offset_arg;
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size_t m_output_offset;
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size_t m_output_offset_arg;
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};
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} // end detail namespace
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/// Copies the elements from the range [\p first, \p last) to the range
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/// beginning at \p result using the output indices from the range beginning
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/// at \p map.
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///
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/// Space complexity: \Omega(1)
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///
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/// \see gather()
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template<class InputIterator, class MapIterator, class OutputIterator>
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inline void scatter(InputIterator first,
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InputIterator last,
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MapIterator map,
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OutputIterator result,
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command_queue &queue = system::default_queue())
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{
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BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
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BOOST_STATIC_ASSERT(is_device_iterator<MapIterator>::value);
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BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
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detail::scatter_kernel<InputIterator, MapIterator, OutputIterator> kernel;
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kernel.set_range(first, last, map, result);
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kernel.exec(queue);
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}
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_ALGORITHM_SCATTER_HPP
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