//---------------------------------------------------------------------------//
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// Copyright (c) 2014 Roshan <thisisroshansmail@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_MERGE_WIH_MERGE_PATH_HPP
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#define BOOST_COMPUTE_ALGORITHM_DETAIL_MERGE_WIH_MERGE_PATH_HPP
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#include <iterator>
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#include <boost/compute/algorithm/detail/merge_path.hpp>
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#include <boost/compute/algorithm/fill_n.hpp>
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#include <boost/compute/container/vector.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/system.hpp>
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namespace boost {
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namespace compute {
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namespace detail {
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///
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/// \brief Serial merge kernel class
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///
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/// Subclass of meta_kernel to perform serial merge after tiling
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///
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class serial_merge_kernel : meta_kernel
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{
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public:
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unsigned int tile_size;
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serial_merge_kernel() : meta_kernel("merge")
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{
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tile_size = 4;
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}
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template<class InputIterator1, class InputIterator2,
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class InputIterator3, class InputIterator4,
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class OutputIterator, class Compare>
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void set_range(InputIterator1 first1,
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InputIterator2 first2,
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InputIterator3 tile_first1,
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InputIterator3 tile_last1,
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InputIterator4 tile_first2,
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OutputIterator result,
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Compare comp)
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{
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m_count = iterator_range_size(tile_first1, tile_last1) - 1;
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*this <<
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"uint i = get_global_id(0);\n" <<
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"uint start1 = " << tile_first1[expr<uint_>("i")] << ";\n" <<
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"uint end1 = " << tile_first1[expr<uint_>("i+1")] << ";\n" <<
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"uint start2 = " << tile_first2[expr<uint_>("i")] << ";\n" <<
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"uint end2 = " << tile_first2[expr<uint_>("i+1")] << ";\n" <<
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"uint index = i*" << tile_size << ";\n" <<
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"while(start1<end1 && start2<end2)\n" <<
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"{\n" <<
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" if(!(" << comp(first2[expr<uint_>("start2")],
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first1[expr<uint_>("start1")]) << "))\n" <<
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" {\n" <<
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result[expr<uint_>("index")] <<
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" = " << first1[expr<uint_>("start1")] << ";\n" <<
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" index++;\n" <<
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" start1++;\n" <<
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" }\n" <<
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" else\n" <<
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" {\n" <<
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result[expr<uint_>("index")] <<
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" = " << first2[expr<uint_>("start2")] << ";\n" <<
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" index++;\n" <<
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" start2++;\n" <<
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" }\n" <<
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"}\n" <<
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"while(start1<end1)\n" <<
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"{\n" <<
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result[expr<uint_>("index")] <<
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" = " << first1[expr<uint_>("start1")] << ";\n" <<
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" index++;\n" <<
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" start1++;\n" <<
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"}\n" <<
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"while(start2<end2)\n" <<
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"{\n" <<
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result[expr<uint_>("index")] <<
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" = " << first2[expr<uint_>("start2")] << ";\n" <<
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" index++;\n" <<
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" start2++;\n" <<
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"}\n";
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}
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template<class InputIterator1, class InputIterator2,
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class InputIterator3, class InputIterator4,
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class OutputIterator>
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void set_range(InputIterator1 first1,
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InputIterator2 first2,
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InputIterator3 tile_first1,
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InputIterator3 tile_last1,
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InputIterator4 tile_first2,
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OutputIterator result)
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{
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typedef typename std::iterator_traits<InputIterator1>::value_type value_type;
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::boost::compute::less<value_type> less_than;
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set_range(first1, first2, tile_first1, tile_last1, tile_first2, result, less_than);
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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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///
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/// \brief Merge algorithm with merge path
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///
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/// Merges the sorted values in the range [\p first1, \p last1) with
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/// the sorted values in the range [\p first2, last2) and stores the
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/// result in the range beginning at \p result
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///
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/// \param first1 Iterator pointing to start of first set
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/// \param last1 Iterator pointing to end of first set
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/// \param first2 Iterator pointing to start of second set
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/// \param last2 Iterator pointing to end of second set
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/// \param result Iterator pointing to start of range in which the result
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/// will be stored
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/// \param comp Comparator which performs less than function
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/// \param queue Queue on which to execute
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///
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template<class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
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inline OutputIterator
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merge_with_merge_path(InputIterator1 first1,
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InputIterator1 last1,
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InputIterator2 first2,
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InputIterator2 last2,
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OutputIterator result,
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Compare comp,
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command_queue &queue = system::default_queue())
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{
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typedef typename
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std::iterator_traits<OutputIterator>::difference_type result_difference_type;
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size_t tile_size = 1024;
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size_t count1 = iterator_range_size(first1, last1);
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size_t count2 = iterator_range_size(first2, last2);
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vector<uint_> tile_a((count1+count2+tile_size-1)/tile_size+1, queue.get_context());
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vector<uint_> tile_b((count1+count2+tile_size-1)/tile_size+1, queue.get_context());
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// Tile the sets
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merge_path_kernel tiling_kernel;
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tiling_kernel.tile_size = static_cast<unsigned int>(tile_size);
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tiling_kernel.set_range(first1, last1, first2, last2,
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tile_a.begin()+1, tile_b.begin()+1, comp);
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fill_n(tile_a.begin(), 1, uint_(0), queue);
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fill_n(tile_b.begin(), 1, uint_(0), queue);
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tiling_kernel.exec(queue);
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fill_n(tile_a.end()-1, 1, static_cast<uint_>(count1), queue);
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fill_n(tile_b.end()-1, 1, static_cast<uint_>(count2), queue);
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// Merge
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serial_merge_kernel merge_kernel;
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merge_kernel.tile_size = static_cast<unsigned int>(tile_size);
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merge_kernel.set_range(first1, first2, tile_a.begin(), tile_a.end(),
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tile_b.begin(), result, comp);
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merge_kernel.exec(queue);
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return result + static_cast<result_difference_type>(count1 + count2);
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}
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/// \overload
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template<class InputIterator1, class InputIterator2, class OutputIterator>
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inline OutputIterator
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merge_with_merge_path(InputIterator1 first1,
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InputIterator1 last1,
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InputIterator2 first2,
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InputIterator2 last2,
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OutputIterator result,
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command_queue &queue = system::default_queue())
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{
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typedef typename std::iterator_traits<InputIterator1>::value_type value_type;
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::boost::compute::less<value_type> less_than;
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return merge_with_merge_path(first1, last1, first2, last2, result, less_than, 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_MERGE_WIH_MERGE_PATH_HPP
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