88 lines
		
	
	
		
			3.2 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			88 lines
		
	
	
		
			3.2 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_DETAIL_SERIAL_FIND_EXTREMA_HPP
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#define BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_FIND_EXTREMA_HPP
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#include <boost/compute/command_queue.hpp>
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#include <boost/compute/types/fundamental.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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#include <boost/compute/container/detail/scalar.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 Compare>
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inline InputIterator serial_find_extrema(InputIterator first,
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                                         InputIterator last,
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                                         Compare compare,
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                                         const bool find_minimum,
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                                         command_queue &queue)
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{
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    typedef typename std::iterator_traits<InputIterator>::value_type value_type;
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    typedef typename std::iterator_traits<InputIterator>::difference_type difference_type;
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    const context &context = queue.get_context();
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    meta_kernel k("serial_find_extrema");
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    k <<
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        k.decl<value_type>("value") << " = " << first[k.expr<uint_>("0")] << ";\n" <<
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        k.decl<uint_>("value_index") << " = 0;\n" <<
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        "for(uint i = 1; i < size; i++){\n" <<
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        "  " << k.decl<value_type>("candidate") << "="
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             << first[k.expr<uint_>("i")] << ";\n" <<
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        "#ifndef BOOST_COMPUTE_FIND_MAXIMUM\n" <<
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        "  if(" << compare(k.var<value_type>("candidate"),
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                           k.var<value_type>("value")) << "){\n" <<
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        "#else\n" <<
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        "  if(" << compare(k.var<value_type>("value"),
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                           k.var<value_type>("candidate")) << "){\n" <<
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        "#endif\n" <<
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        "    value = candidate;\n" <<
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        "    value_index = i;\n" <<
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        "  }\n" <<
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        "}\n" <<
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        "*index = value_index;\n";
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    size_t index_arg_index = k.add_arg<uint_ *>(memory_object::global_memory, "index");
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    size_t size_arg_index = k.add_arg<uint_>("size");
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    std::string options;
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    if(!find_minimum){
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        options = "-DBOOST_COMPUTE_FIND_MAXIMUM";
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    }
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    kernel kernel = k.compile(context, options);
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    // setup index buffer
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    scalar<uint_> index(context);
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    kernel.set_arg(index_arg_index, index.get_buffer());
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    // setup count
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    size_t count = iterator_range_size(first, last);
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    kernel.set_arg(size_arg_index, static_cast<uint_>(count));
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    // run kernel
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    queue.enqueue_task(kernel);
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    // read index and return iterator
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    return first + static_cast<difference_type>(index.read(queue));
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}
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} // end detail namespace
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_FIND_EXTREMA_HPP
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