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

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2014 Mageswaran.D <mageswaran1989@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 #include <boost/compute/system.hpp>
  12 #include <boost/compute/context.hpp>
  13 #include <boost/compute/command_queue.hpp>
  14 #include <boost/compute/algorithm/any_of.hpp>
  15 #include <boost/compute/container/vector.hpp>
  16 #include <boost/compute/utility/program_cache.hpp>
  17
  18 namespace boost {
  19 namespace compute {
  20
  21 namespace detail {
  22
  23 const char lexicographical_compare_source[] =
  24 "__kernel void lexicographical_compare(const uint size1,\n"
  25 "                                      const uint size2,\n"
  26 "                                      __global const T1 *range1,\n"
  27 "                                      __global const T2 *range2,\n"
  28 "                                      __global bool *result_buf)\n"
  29 "{\n"
  30 "   const uint i = get_global_id(0);\n"
  31 "   if((i != size1) && (i != size2)){\n"
  32         //Individual elements are compared and results are stored in parallel.
  33         //0 is true
  34 "       if(range1[i] < range2[i])\n"
  35 "           result_buf[i] = 0;\n"
  36 "       else\n"
  37 "           result_buf[i] = 1;\n"
  38 "   }\n"
  39 "   else\n"
  40 "       result_buf[i] = !((i == size1) && (i != size2));\n"
  41 "}\n";
  42
  43 template<class InputIterator1, class InputIterator2>
  44 inline bool dispatch_lexicographical_compare(InputIterator1 first1,
  45                                              InputIterator1 last1,
  46                                              InputIterator2 first2,
  47                                              InputIterator2 last2,
  48                                              command_queue &queue)
  49 {
  50     const boost::compute::context &context = queue.get_context();
  51
  52     boost::shared_ptr<program_cache> cache =
  53         program_cache::get_global_cache(context);
  54
  55     size_t iterator_size1 = iterator_range_size(first1, last1);
  56     size_t iterator_size2 = iterator_range_size(first2, last2);
  57     size_t max_size = (std::max)(iterator_size1, iterator_size2);
  58
  59     if(max_size == 0){
  60         return false;
  61     }
  62
  63     boost::compute::vector<bool> result_vector(max_size, context);
  64
  65
  66     typedef typename std::iterator_traits<InputIterator1>::value_type value_type1;
  67     typedef typename std::iterator_traits<InputIterator2>::value_type value_type2;
  68
  69     // load (or create) lexicographical compare program
  70     std::string cache_key =
  71             std::string("__boost_lexicographical_compare")
  72             + type_name<value_type1>() + type_name<value_type2>();
  73
  74     std::stringstream options;
  75     options << " -DT1=" << type_name<value_type1>();
  76     options << " -DT2=" << type_name<value_type2>();
  77
  78     program lexicographical_compare_program = cache->get_or_build(
  79         cache_key, options.str(), lexicographical_compare_source, context
  80     );
  81
  82     kernel lexicographical_compare_kernel(lexicographical_compare_program,
  83                                           "lexicographical_compare");
  84
  85     lexicographical_compare_kernel.set_arg<uint_>(0, iterator_size1);
  86     lexicographical_compare_kernel.set_arg<uint_>(1, iterator_size2);
  87     lexicographical_compare_kernel.set_arg(2, first1.get_buffer());
  88     lexicographical_compare_kernel.set_arg(3, first2.get_buffer());
  89     lexicographical_compare_kernel.set_arg(4, result_vector.get_buffer());
  90
  91     queue.enqueue_1d_range_kernel(lexicographical_compare_kernel,
  92                                   0,
  93                                   max_size,
  94                                   0);
  95
  96     return boost::compute::any_of(result_vector.begin(),
  97                                   result_vector.end(),
  98                                   _1 == 0,
  99                                   queue);
 100 }
 101
 102 } // end detail namespace
 103
 104 /// Checks if the first range [first1, last1) is lexicographically
 105 /// less than the second range [first2, last2).
 106 ///
 107 /// Space complexity:
 108 /// \Omega(max(distance(\p first1, \p last1), distance(\p first2, \p last2)))
 109 template<class InputIterator1, class InputIterator2>
 110 inline bool lexicographical_compare(InputIterator1 first1,
 111                                     InputIterator1 last1,
 112                                     InputIterator2 first2,
 113                                     InputIterator2 last2,
 114                                     command_queue &queue = system::default_queue())
 115 {
 116     return detail::dispatch_lexicographical_compare(first1, last1, first2, last2, queue);
 117 }
 118
 119 } // end compute namespace
 120 } // end boost namespac