118 lines
4.4 KiB
Plaintext
118 lines
4.4 KiB
Plaintext
//---------------------------------------------------------------------------//
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// Copyright (c) 2013-2015 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_TRANSFORM_IF_HPP
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#define BOOST_COMPUTE_ALGORITHM_TRANSFORM_IF_HPP
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#include <boost/compute/cl.hpp>
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#include <boost/compute/system.hpp>
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#include <boost/compute/command_queue.hpp>
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#include <boost/compute/algorithm/count.hpp>
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#include <boost/compute/algorithm/count_if.hpp>
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#include <boost/compute/algorithm/exclusive_scan.hpp>
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#include <boost/compute/container/vector.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/iterator/discard_iterator.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 OutputIterator, class UnaryFunction, class Predicate>
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inline OutputIterator transform_if_impl(InputIterator first,
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InputIterator last,
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OutputIterator result,
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UnaryFunction function,
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Predicate predicate,
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bool copyIndex,
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command_queue &queue)
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{
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typedef typename std::iterator_traits<OutputIterator>::difference_type difference_type;
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size_t count = detail::iterator_range_size(first, last);
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if(count == 0){
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return result;
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}
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const context &context = queue.get_context();
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// storage for destination indices
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::boost::compute::vector<cl_uint> indices(count, context);
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// write counts
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::boost::compute::detail::meta_kernel k1("transform_if_write_counts");
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k1 << indices.begin()[k1.get_global_id(0)] << " = "
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<< predicate(first[k1.get_global_id(0)]) << " ? 1 : 0;\n";
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k1.exec_1d(queue, 0, count);
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// count number of elements to be copied
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size_t copied_element_count =
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::boost::compute::count(indices.begin(), indices.end(), 1, queue);
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// scan indices
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::boost::compute::exclusive_scan(
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indices.begin(), indices.end(), indices.begin(), queue
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);
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// copy values
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::boost::compute::detail::meta_kernel k2("transform_if_do_copy");
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k2 << "if(" << predicate(first[k2.get_global_id(0)]) << ")" <<
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" " << result[indices.begin()[k2.get_global_id(0)]] << "=";
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if(copyIndex){
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k2 << k2.get_global_id(0) << ";\n";
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}
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else {
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k2 << function(first[k2.get_global_id(0)]) << ";\n";
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}
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k2.exec_1d(queue, 0, count);
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return result + static_cast<difference_type>(copied_element_count);
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}
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template<class InputIterator, class UnaryFunction, class Predicate>
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inline discard_iterator transform_if_impl(InputIterator first,
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InputIterator last,
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discard_iterator result,
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UnaryFunction function,
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Predicate predicate,
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bool copyIndex,
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command_queue &queue)
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{
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(void) function;
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(void) copyIndex;
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return result + count_if(first, last, predicate, queue);
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}
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} // end detail namespace
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/// Copies each element in the range [\p first, \p last) for which
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/// \p predicate returns \c true to the range beginning at \p result.
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template<class InputIterator, class OutputIterator, class UnaryFunction, class Predicate>
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inline OutputIterator transform_if(InputIterator first,
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InputIterator last,
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OutputIterator result,
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UnaryFunction function,
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Predicate predicate,
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command_queue &queue = system::default_queue())
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{
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return detail::transform_if_impl(
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first, last, result, function, predicate, false, queue
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);
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}
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_ALGORITHM_TRANSFORM_IF_HPP
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