76 lines
2.5 KiB
Plaintext
76 lines
2.5 KiB
Plaintext
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//---------------------------------------------------------------------------//
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// Copyright (c) 2013 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_RANDOM_SHUFFLE_HPP
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#define BOOST_COMPUTE_ALGORITHM_RANDOM_SHUFFLE_HPP
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#include <vector>
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#include <algorithm>
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#include <boost/range/algorithm_ext/iota.hpp>
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#include <boost/compute/system.hpp>
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#include <boost/compute/functional.hpp>
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#include <boost/compute/command_queue.hpp>
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#include <boost/compute/container/vector.hpp>
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#include <boost/compute/algorithm/scatter.hpp>
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#include <boost/compute/detail/iterator_range_size.hpp>
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namespace boost {
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namespace compute {
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/// Randomly shuffles the elements in the range [\p first, \p last).
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///
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/// \see scatter()
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template<class Iterator>
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inline void random_shuffle(Iterator first,
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Iterator last,
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command_queue &queue = system::default_queue())
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{
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typedef typename std::iterator_traits<Iterator>::value_type value_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;
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}
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// generate shuffled indices on the host
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std::vector<cl_uint> random_indices(count);
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boost::iota(random_indices, 0);
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std::random_shuffle(random_indices.begin(), random_indices.end());
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// copy random indices to the device
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const context &context = queue.get_context();
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vector<cl_uint> indices(count, context);
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::boost::compute::copy(random_indices.begin(),
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random_indices.end(),
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indices.begin(),
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queue);
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// make a copy of the values on the device
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vector<value_type> tmp(count, context);
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::boost::compute::copy(first,
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last,
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tmp.begin(),
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queue);
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// write values to their new locations
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::boost::compute::scatter(tmp.begin(),
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tmp.end(),
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indices.begin(),
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first,
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queue);
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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_RANDOM_SHUFFLE_HPP
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