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