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- //---------------------------------------------------------------------------//
- // Copyright (c) 2014 Roshan <thisisroshansmail@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_DETAIL_BALANCED_PATH_HPP
- #define BOOST_COMPUTE_ALGORITHM_DETAIL_BALANCED_PATH_HPP
- #include <iterator>
- #include <boost/compute/algorithm/find_if.hpp>
- #include <boost/compute/container/vector.hpp>
- #include <boost/compute/detail/iterator_range_size.hpp>
- #include <boost/compute/detail/meta_kernel.hpp>
- #include <boost/compute/lambda.hpp>
- #include <boost/compute/system.hpp>
- namespace boost {
- namespace compute {
- namespace detail {
- ///
- /// \brief Balanced Path kernel class
- ///
- /// Subclass of meta_kernel to break two sets into tiles according
- /// to their balanced path.
- ///
- class balanced_path_kernel : public meta_kernel
- {
- public:
- unsigned int tile_size;
- balanced_path_kernel() : meta_kernel("balanced_path")
- {
- tile_size = 4;
- }
- template<class InputIterator1, class InputIterator2,
- class OutputIterator1, class OutputIterator2,
- class Compare>
- void set_range(InputIterator1 first1,
- InputIterator1 last1,
- InputIterator2 first2,
- InputIterator2 last2,
- OutputIterator1 result_a,
- OutputIterator2 result_b,
- Compare comp)
- {
- typedef typename std::iterator_traits<InputIterator1>::value_type value_type;
- m_a_count = iterator_range_size(first1, last1);
- m_a_count_arg = add_arg<uint_>("a_count");
- m_b_count = iterator_range_size(first2, last2);
- m_b_count_arg = add_arg<uint_>("b_count");
- *this <<
- "uint i = get_global_id(0);\n" <<
- "uint target = (i+1)*" << tile_size << ";\n" <<
- "uint start = max(convert_int(0),convert_int(target)-convert_int(b_count));\n" <<
- "uint end = min(target,a_count);\n" <<
- "uint a_index, b_index;\n" <<
- "while(start<end)\n" <<
- "{\n" <<
- " a_index = (start + end)/2;\n" <<
- " b_index = target - a_index - 1;\n" <<
- " if(!(" << comp(first2[expr<uint_>("b_index")],
- first1[expr<uint_>("a_index")]) << "))\n" <<
- " start = a_index + 1;\n" <<
- " else end = a_index;\n" <<
- "}\n" <<
- "a_index = start;\n" <<
- "b_index = target - start;\n" <<
- "if(b_index < b_count)\n" <<
- "{\n" <<
- " " << decl<const value_type>("x") << " = " <<
- first2[expr<uint_>("b_index")] << ";\n" <<
- " uint a_start = 0, a_end = a_index, a_mid;\n" <<
- " uint b_start = 0, b_end = b_index, b_mid;\n" <<
- " while(a_start<a_end)\n" <<
- " {\n" <<
- " a_mid = (a_start + a_end)/2;\n" <<
- " if(" << comp(first1[expr<uint_>("a_mid")], expr<value_type>("x")) << ")\n" <<
- " a_start = a_mid+1;\n" <<
- " else a_end = a_mid;\n" <<
- " }\n" <<
- " while(b_start<b_end)\n" <<
- " {\n" <<
- " b_mid = (b_start + b_end)/2;\n" <<
- " if(" << comp(first2[expr<uint_>("b_mid")], expr<value_type>("x")) << ")\n" <<
- " b_start = b_mid+1;\n" <<
- " else b_end = b_mid;\n" <<
- " }\n" <<
- " uint a_run = a_index - a_start;\n" <<
- " uint b_run = b_index - b_start;\n" <<
- " uint x_count = a_run + b_run;\n" <<
- " uint b_advance = max(x_count / 2, x_count - a_run);\n" <<
- " b_end = min(b_count, b_start + b_advance + 1);\n" <<
- " uint temp_start = b_index, temp_end = b_end, temp_mid;" <<
- " while(temp_start < temp_end)\n" <<
- " {\n" <<
- " temp_mid = (temp_start + temp_end + 1)/2;\n" <<
- " if(" << comp(expr<value_type>("x"), first2[expr<uint_>("temp_mid")]) << ")\n" <<
- " temp_end = temp_mid-1;\n" <<
- " else temp_start = temp_mid;\n" <<
- " }\n" <<
- " b_run = temp_start - b_start + 1;\n" <<
- " b_advance = min(b_advance, b_run);\n" <<
- " uint a_advance = x_count - b_advance;\n" <<
- " uint star = convert_uint((a_advance == b_advance + 1) " <<
- "&& (b_advance < b_run));\n" <<
- " a_index = a_start + a_advance;\n" <<
- " b_index = target - a_index + star;\n" <<
- "}\n" <<
- result_a[expr<uint_>("i")] << " = a_index;\n" <<
- result_b[expr<uint_>("i")] << " = b_index;\n";
- }
- template<class InputIterator1, class InputIterator2,
- class OutputIterator1, class OutputIterator2>
- void set_range(InputIterator1 first1,
- InputIterator1 last1,
- InputIterator2 first2,
- InputIterator2 last2,
- OutputIterator1 result_a,
- OutputIterator2 result_b)
- {
- typedef typename std::iterator_traits<InputIterator1>::value_type value_type;
- ::boost::compute::less<value_type> less_than;
- set_range(first1, last1, first2, last2, result_a, result_b, less_than);
- }
- event exec(command_queue &queue)
- {
- if((m_a_count + m_b_count)/tile_size == 0) {
- return event();
- }
- set_arg(m_a_count_arg, uint_(m_a_count));
- set_arg(m_b_count_arg, uint_(m_b_count));
- return exec_1d(queue, 0, (m_a_count + m_b_count)/tile_size);
- }
- private:
- size_t m_a_count;
- size_t m_a_count_arg;
- size_t m_b_count;
- size_t m_b_count_arg;
- };
- } //end detail namespace
- } //end compute namespace
- } //end boost namespace
- #endif // BOOST_COMPUTE_ALGORITHM_DETAIL_BALANCED_PATH_HPP
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