ceph/src/boost/boost/compute/algorithm/stable_sort.hpp

   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_STABLE_SORT_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_STABLE_SORT_HPP
  13
  14 #include <iterator>
  15
  16 #include <boost/static_assert.hpp>
  17
  18 #include <boost/compute/system.hpp>
  19 #include <boost/compute/command_queue.hpp>
  20 #include <boost/compute/algorithm/detail/merge_sort_on_cpu.hpp>
  21 #include <boost/compute/algorithm/detail/merge_sort_on_gpu.hpp>
  22 #include <boost/compute/algorithm/detail/radix_sort.hpp>
  23 #include <boost/compute/algorithm/detail/insertion_sort.hpp>
  24 #include <boost/compute/algorithm/reverse.hpp>
  25 #include <boost/compute/functional/operator.hpp>
  26 #include <boost/compute/detail/iterator_range_size.hpp>
  27 #include <boost/compute/type_traits/is_device_iterator.hpp>
  28
  29 namespace boost {
  30 namespace compute {
  31 namespace detail {
  32
  33 template<class Iterator, class Compare>
  34 inline void dispatch_gpu_stable_sort(Iterator first,
  35                                      Iterator last,
  36                                      Compare compare,
  37                                      command_queue &queue)
  38 {
  39     size_t count = detail::iterator_range_size(first, last);
  40
  41     if(count < 32){
  42         detail::serial_insertion_sort(
  43             first, last, compare, queue
  44         );
  45     } else {
  46         detail::merge_sort_on_gpu(
  47             first, last, compare, true /* stable */, queue
  48         );
  49     }
  50 }
  51
  52 template<class T>
  53 inline typename boost::enable_if_c<is_radix_sortable<T>::value>::type
  54 dispatch_gpu_stable_sort(buffer_iterator<T> first,
  55                          buffer_iterator<T> last,
  56                          less<T>,
  57                          command_queue &queue)
  58 {
  59     ::boost::compute::detail::radix_sort(first, last, queue);
  60 }
  61
  62 template<class T>
  63 inline typename boost::enable_if_c<is_radix_sortable<T>::value>::type
  64 dispatch_gpu_stable_sort(buffer_iterator<T> first,
  65                          buffer_iterator<T> last,
  66                          greater<T>,
  67                          command_queue &queue)
  68 {
  69     // radix sorts in descending order
  70     ::boost::compute::detail::radix_sort(first, last, false, queue);
  71 }
  72
  73 } // end detail namespace
  74
  75 /// Sorts the values in the range [\p first, \p last) according to
  76 /// \p compare. The relative order of identical values is preserved.
  77 ///
  78 /// Space complexity: \Omega(n)
  79 ///
  80 /// \see sort(), is_sorted()
  81 template<class Iterator, class Compare>
  82 inline void stable_sort(Iterator first,
  83                         Iterator last,
  84                         Compare compare,
  85                         command_queue &queue = system::default_queue())
  86 {
  87     BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value);
  88
  89     if(queue.get_device().type() & device::gpu) {
  90         ::boost::compute::detail::dispatch_gpu_stable_sort(
  91             first, last, compare, queue
  92         );
  93         return;
  94     }
  95     ::boost::compute::detail::merge_sort_on_cpu(first, last, compare, queue);
  96 }
  97
  98 /// \overload
  99 template<class Iterator>
 100 inline void stable_sort(Iterator first,
 101                         Iterator last,
 102                         command_queue &queue = system::default_queue())
 103 {
 104     BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value);
 105     typedef typename std::iterator_traits<Iterator>::value_type value_type;
 106
 107     ::boost::compute::less<value_type> less;
 108
 109     ::boost::compute::stable_sort(first, last, less, queue);
 110 }
 111
 112 } // end compute namespace
 113 } // end boost namespace
 114
 115 #endif // BOOST_COMPUTE_ALGORITHM_STABLE_SORT_HPP