75 lines
		
	
	
		
			2.3 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			75 lines
		
	
	
		
			2.3 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_REVERSE_HPP
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#define BOOST_COMPUTE_ALGORITHM_REVERSE_HPP
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#include <boost/compute/system.hpp>
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#include <boost/compute/command_queue.hpp>
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#include <boost/compute/detail/meta_kernel.hpp>
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#include <boost/compute/detail/iterator_range_size.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 Iterator>
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struct reverse_kernel : public meta_kernel
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{
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    reverse_kernel(Iterator first, Iterator last)
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        : meta_kernel("reverse")
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    {
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        typedef typename std::iterator_traits<Iterator>::value_type value_type;
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        // store size of the range
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        m_size = detail::iterator_range_size(first, last);
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        add_set_arg<const cl_uint>("size", static_cast<const cl_uint>(m_size));
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        *this <<
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            decl<cl_uint>("i") << " = get_global_id(0);\n" <<
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            decl<cl_uint>("j") << " = size - get_global_id(0) - 1;\n" <<
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            decl<value_type>("tmp") << "=" << first[var<cl_uint>("i")] << ";\n" <<
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            first[var<cl_uint>("i")] << "=" << first[var<cl_uint>("j")] << ";\n" <<
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            first[var<cl_uint>("j")] << "= tmp;\n";
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    }
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    void exec(command_queue &queue)
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    {
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        exec_1d(queue, 0, m_size / 2);
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    }
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    size_t m_size;
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};
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} // end detail namespace
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/// Reverses the elements in the range [\p first, \p last).
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///
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/// \see reverse_copy()
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template<class Iterator>
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inline void reverse(Iterator first,
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                    Iterator last,
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                    command_queue &queue = system::default_queue())
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{
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    size_t count = detail::iterator_range_size(first, last);
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    if(count < 2){
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        return;
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    }
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    detail::reverse_kernel<Iterator> kernel(first, last);
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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_REVERSE_HPP
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