83 lines
		
	
	
		
			2.5 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			83 lines
		
	
	
		
			2.5 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
//---------------------------------------------------------------------------//
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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_GATHER_HPP
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#define BOOST_COMPUTE_ALGORITHM_GATHER_HPP
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#include <boost/compute/command_queue.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/exception.hpp>
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#include <boost/compute/iterator/buffer_iterator.hpp>
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#include <boost/compute/system.hpp>
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#include <boost/compute/type_traits/type_name.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 gather_kernel : public meta_kernel
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{
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public:
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    gather_kernel() : meta_kernel("gather")
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    {}
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    void set_range(MapIterator first,
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                   MapIterator last,
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                   InputIterator input,
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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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        *this <<
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            "const uint i = get_global_id(0);\n" <<
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            result[expr<uint_>("i")] << "=" << 
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                input[first[expr<uint_>("i")]] << ";\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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        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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};
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} // end detail namespace
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/// Copies the elements using the indices from the range [\p first, \p last)
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/// to the range beginning at \p result using the input values from the range
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/// beginning at \p input.
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///
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/// \see scatter()
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template<class InputIterator, class MapIterator, class OutputIterator>
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inline void gather(MapIterator first,
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                   MapIterator last,
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                   InputIterator input,
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                   OutputIterator result,
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                   command_queue &queue = system::default_queue())
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{
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    detail::gather_kernel<InputIterator, MapIterator, OutputIterator> kernel;
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    kernel.set_range(first, last, input, 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_GATHER_HPP
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