ceph/src/boost/boost/compute/algorithm/transform_reduce.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_TRANSFORM_REDUCE_HPP
  12 #define BOOST_COMPUTE_ALGORITHM_TRANSFORM_REDUCE_HPP
  13
  14 #include <boost/static_assert.hpp>
  15
  16 #include <boost/compute/system.hpp>
  17 #include <boost/compute/algorithm/reduce.hpp>
  18 #include <boost/compute/iterator/transform_iterator.hpp>
  19 #include <boost/compute/iterator/zip_iterator.hpp>
  20 #include <boost/compute/functional/detail/unpack.hpp>
  21 #include <boost/compute/detail/iterator_range_size.hpp>
  22 #include <boost/compute/type_traits/is_device_iterator.hpp>
  23
  24 namespace boost {
  25 namespace compute {
  26
  27 /// Transforms each value in the range [\p first, \p last) with the unary
  28 /// \p transform_function and then reduces each transformed value with
  29 /// \p reduce_function.
  30 ///
  31 /// For example, to calculate the sum of the absolute values of a vector
  32 /// of integers:
  33 ///
  34 /// \snippet test/test_transform_reduce.cpp sum_abs_int
  35 ///
  36 /// Space complexity on GPUs: \Omega(n)<br>
  37 /// Space complexity on CPUs: \Omega(1)
  38 ///
  39 /// \see reduce(), inner_product()
  40 template<class InputIterator,
  41          class OutputIterator,
  42          class UnaryTransformFunction,
  43          class BinaryReduceFunction>
  44 inline void transform_reduce(InputIterator first,
  45                              InputIterator last,
  46                              OutputIterator result,
  47                              UnaryTransformFunction transform_function,
  48                              BinaryReduceFunction reduce_function,
  49                              command_queue &queue = system::default_queue())
  50 {
  51     BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
  52     ::boost::compute::reduce(
  53         ::boost::compute::make_transform_iterator(first, transform_function),
  54         ::boost::compute::make_transform_iterator(last, transform_function),
  55         result,
  56         reduce_function,
  57         queue
  58     );
  59 }
  60
  61 /// \overload
  62 template<class InputIterator1,
  63          class InputIterator2,
  64          class OutputIterator,
  65          class BinaryTransformFunction,
  66          class BinaryReduceFunction>
  67 inline void transform_reduce(InputIterator1 first1,
  68                              InputIterator1 last1,
  69                              InputIterator2 first2,
  70                              OutputIterator result,
  71                              BinaryTransformFunction transform_function,
  72                              BinaryReduceFunction reduce_function,
  73                              command_queue &queue = system::default_queue())
  74 {
  75     BOOST_STATIC_ASSERT(is_device_iterator<InputIterator1>::value);
  76     BOOST_STATIC_ASSERT(is_device_iterator<InputIterator2>::value);
  77     BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
  78
  79     typedef typename std::iterator_traits<InputIterator1>::difference_type difference_type;
  80
  81     difference_type n = std::distance(first1, last1);
  82
  83     ::boost::compute::transform_reduce(
  84         ::boost::compute::make_zip_iterator(
  85             boost::make_tuple(first1, first2)
  86         ),
  87         ::boost::compute::make_zip_iterator(
  88             boost::make_tuple(last1, first2 + n)
  89         ),
  90         result,
  91         detail::unpack(transform_function),
  92         reduce_function,
  93         queue
  94     );
  95 }
  96
  97 } // end compute namespace
  98 } // end boost namespace
  99
 100 #endif // BOOST_COMPUTE_ALGORITHM_TRANSFORM_REDUCE_HPP