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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_GATHER_HPP
#define BOOST_COMPUTE_ALGORITHM_GATHER_HPP
#include <boost/compute/command_queue.hpp>
#include <boost/compute/detail/iterator_range_size.hpp>
#include <boost/compute/detail/meta_kernel.hpp>
#include <boost/compute/exception.hpp>
#include <boost/compute/iterator/buffer_iterator.hpp>
#include <boost/compute/system.hpp>
#include <boost/compute/type_traits/type_name.hpp>
namespace boost {
namespace compute {
namespace detail {
template<class InputIterator, class MapIterator, class OutputIterator>
class gather_kernel : public meta_kernel
{
public:
gather_kernel() : meta_kernel("gather")
{}
void set_range(MapIterator first,
MapIterator last,
InputIterator input,
OutputIterator result)
{
m_count = iterator_range_size(first, last);
*this <<
"const uint i = get_global_id(0);\n" <<
result[expr<uint_>("i")] << "=" <<
input[first[expr<uint_>("i")]] << ";\n";
}
event exec(command_queue &queue)
{
if(m_count == 0) {
return event();
}
return exec_1d(queue, 0, m_count);
}
private:
size_t m_count;
};
} // end detail namespace
/// Copies the elements using the indices from the range [\p first, \p last)
/// to the range beginning at \p result using the input values from the range
/// beginning at \p input.
///
/// Space complexity: \Omega(1)
///
/// \see scatter()
template<class InputIterator, class MapIterator, class OutputIterator>
inline void gather(MapIterator first,
MapIterator last,
InputIterator input,
OutputIterator result,
command_queue &queue = system::default_queue())
{
detail::gather_kernel<InputIterator, MapIterator, OutputIterator> kernel;
kernel.set_range(first, last, input, result);
kernel.exec(queue);
}
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_ALGORITHM_GATHER_HPP
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