projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | //---------------------------------------------------------------------------// |
| 2 | // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com> | |
| 3 | // | |
| 4 | // Distributed under the Boost Software License, Version 1.0 | |
| 5 | // See accompanying file LICENSE_1_0.txt or copy at | |
| 6 | // http://www.boost.org/LICENSE_1_0.txt | |
| 7 | // | |
| 8 | // See http://boostorg.github.com/compute for more information. | |
| 9 | //---------------------------------------------------------------------------// | |
| 10 | ||
| 11 | #ifndef BOOST_COMPUTE_ALGORITHM_RANDOM_SHUFFLE_HPP | |
| 12 | #define BOOST_COMPUTE_ALGORITHM_RANDOM_SHUFFLE_HPP | |
| 13 | ||
| 14 | #include <vector> | |
| 15 | #include <algorithm> | |
| 16 | ||
| 17 | #include <boost/range/algorithm_ext/iota.hpp> | |
| 18 | ||
| 19 | #include <boost/compute/system.hpp> | |
| 20 | #include <boost/compute/functional.hpp> | |
| 21 | #include <boost/compute/command_queue.hpp> | |
| 22 | #include <boost/compute/container/vector.hpp> | |
| 23 | #include <boost/compute/algorithm/scatter.hpp> | |
| 24 | #include <boost/compute/detail/iterator_range_size.hpp> | |
| 25 | ||
| 26 | namespace boost { | |
| 27 | namespace compute { | |
| 28 | ||
| 29 | /// Randomly shuffles the elements in the range [\p first, \p last). | |
| 30 | /// | |
| 31 | /// \see scatter() | |
| 32 | template<class Iterator> | |
| 33 | inline void random_shuffle(Iterator first, | |
| 34 | Iterator last, | |
| 35 | command_queue &queue = system::default_queue()) | |
| 36 | { | |
| 37 | typedef typename std::iterator_traits<Iterator>::value_type value_type; | |
| 38 | ||
| 39 | size_t count = detail::iterator_range_size(first, last); | |
| 40 | if(count == 0){ | |
| 41 | return; | |
| 42 | } | |
| 43 | ||
| 44 | // generate shuffled indices on the host | |
| 45 | std::vector<cl_uint> random_indices(count); | |
| 46 | boost::iota(random_indices, 0); | |
| 47 | std::random_shuffle(random_indices.begin(), random_indices.end()); | |
| 48 | ||
| 49 | // copy random indices to the device | |
| 50 | const context &context = queue.get_context(); | |
| 51 | vector<cl_uint> indices(count, context); | |
| 52 | ::boost::compute::copy(random_indices.begin(), | |
| 53 | random_indices.end(), | |
| 54 | indices.begin(), | |
| 55 | queue); | |
| 56 | ||
| 57 | // make a copy of the values on the device | |
| 58 | vector<value_type> tmp(count, context); | |
| 59 | ::boost::compute::copy(first, | |
| 60 | last, | |
| 61 | tmp.begin(), | |
| 62 | queue); | |
| 63 | ||
| 64 | // write values to their new locations | |
| 65 | ::boost::compute::scatter(tmp.begin(), | |
| 66 | tmp.end(), | |
| 67 | indices.begin(), | |
| 68 | first, | |
| 69 | queue); | |
| 70 | } | |
| 71 | ||
| 72 | } // end compute namespace | |
| 73 | } // end boost namespace | |
| 74 | ||
| 75 | #endif // BOOST_COMPUTE_ALGORITHM_RANDOM_SHUFFLE_HPP |