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//---------------------------------------------------------------------------//
// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
//
// Distributed under the Boost Software License, Version 1.0
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
//
// See http://boostorg.github.com/compute for more information.
//---------------------------------------------------------------------------//
#ifndef BOOST_COMPUTE_ALGORITHM_SERIAL_MERGE_HPP
#define BOOST_COMPUTE_ALGORITHM_SERIAL_MERGE_HPP
#include <iterator>
#include <boost/compute/command_queue.hpp>
#include <boost/compute/detail/meta_kernel.hpp>
#include <boost/compute/detail/iterator_range_size.hpp>
namespace boost {
namespace compute {
namespace detail {
template<class InputIterator1,
class InputIterator2,
class OutputIterator,
class Compare>
inline OutputIterator serial_merge(InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
InputIterator2 last2,
OutputIterator result,
Compare comp,
command_queue &queue)
{
typedef typename
std::iterator_traits<InputIterator1>::value_type
input_type1;
typedef typename
std::iterator_traits<InputIterator2>::value_type
input_type2;
typedef typename
std::iterator_traits<OutputIterator>::difference_type
result_difference_type;
std::ptrdiff_t size1 = std::distance(first1, last1);
std::ptrdiff_t size2 = std::distance(first2, last2);
meta_kernel k("serial_merge");
k.add_set_arg<uint_>("size1", static_cast<uint_>(size1));
k.add_set_arg<uint_>("size2", static_cast<uint_>(size2));
k <<
"uint i = 0;\n" << // index in result range
"uint j = 0;\n" << // index in first input range
"uint k = 0;\n" << // index in second input range
// fetch initial values from each range
k.decl<input_type1>("j_value") << " = " << first1[0] << ";\n" <<
k.decl<input_type2>("k_value") << " = " << first2[0] << ";\n" <<
// merge values from both input ranges to the result range
"while(j < size1 && k < size2){\n" <<
" if(" << comp(k.var<input_type1>("j_value"),
k.var<input_type2>("k_value")) << "){\n" <<
" " << result[k.var<uint_>("i++")] << " = j_value;\n" <<
" j_value = " << first1[k.var<uint_>("++j")] << ";\n" <<
" }\n" <<
" else{\n"
" " << result[k.var<uint_>("i++")] << " = k_value;\n"
" k_value = " << first2[k.var<uint_>("++k")] << ";\n" <<
" }\n"
"}\n"
// copy any remaining values from first range
"while(j < size1){\n" <<
result[k.var<uint_>("i++")] << " = " <<
first1[k.var<uint_>("j++")] << ";\n" <<
"}\n"
// copy any remaining values from second range
"while(k < size2){\n" <<
result[k.var<uint_>("i++")] << " = " <<
first2[k.var<uint_>("k++")] << ";\n" <<
"}\n";
// run kernel
k.exec(queue);
return result + static_cast<result_difference_type>(size1 + size2);
}
} // end detail namespace
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_ALGORITHM_SERIAL_MERGE_HPP
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