ceph/src/boost/boost/compute/random/bernoulli_distribution.hpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2014 Roshan <thisisroshansmail@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_RANDOM_BERNOULLI_DISTRIBUTION_HPP
  12 #define BOOST_COMPUTE_RANDOM_BERNOULLI_DISTRIBUTION_HPP
  13
  14 #include <boost/assert.hpp>
  15 #include <boost/type_traits.hpp>
  16
  17 #include <boost/compute/command_queue.hpp>
  18 #include <boost/compute/function.hpp>
  19 #include <boost/compute/types/fundamental.hpp>
  20 #include <boost/compute/detail/iterator_range_size.hpp>
  21 #include <boost/compute/detail/literal.hpp>
  22
  23 namespace boost {
  24 namespace compute {
  25
  26 ///
  27 /// \class bernoulli_distribution
  28 /// \brief Produces random boolean values according to the following
  29 /// discrete probability function with parameter p :
  30 /// P(true/p) = p and P(false/p) = (1 - p)
  31 ///
  32 /// The following example shows how to setup a bernoulli distribution to
  33 /// produce random boolean values with parameter p = 0.25
  34 ///
  35 /// \snippet test/test_bernoulli_distribution.cpp generate
  36 ///
  37 template<class RealType = float>
  38 class bernoulli_distribution
  39 {
  40 public:
  41
  42     /// Creates a new bernoulli distribution
  43     bernoulli_distribution(RealType p = 0.5f)
  44         : m_p(p)
  45     {
  46     }
  47
  48     /// Destroys the bernoulli_distribution object
  49     ~bernoulli_distribution()
  50     {
  51     }
  52
  53     /// Returns the value of the parameter p
  54     RealType p() const
  55     {
  56         return m_p;
  57     }
  58
  59     /// Generates bernoulli distributed booleans and stores
  60     /// them in the range [\p first, \p last).
  61     template<class OutputIterator, class Generator>
  62     void generate(OutputIterator first,
  63                   OutputIterator last,
  64                   Generator &generator,
  65                   command_queue &queue)
  66     {
  67         size_t count = detail::iterator_range_size(first, last);
  68
  69         vector<uint_> tmp(count, queue.get_context());
  70         generator.generate(tmp.begin(), tmp.end(), queue);
  71
  72         BOOST_COMPUTE_FUNCTION(bool, scale_random, (const uint_ x),
  73         {
  74             return (convert_RealType(x) / MAX_RANDOM) < PARAM;
  75         });
  76
  77         scale_random.define("PARAM", detail::make_literal(m_p));
  78         scale_random.define("MAX_RANDOM", "UINT_MAX");
  79         scale_random.define(
  80             "convert_RealType", std::string("convert_") + type_name<RealType>()
  81         );
  82
  83         transform(
  84             tmp.begin(), tmp.end(), first, scale_random, queue
  85         );
  86     }
  87
  88 private:
  89     RealType m_p;
  90
  91     BOOST_STATIC_ASSERT_MSG(
  92         boost::is_floating_point<RealType>::value,
  93         "Template argument must be a floating point type"
  94     );
  95 };
  96
  97 } // end compute namespace
  98 } // end boost namespace
  99
 100 #endif // BOOST_COMPUTE_RANDOM_BERNOULLI_DISTRIBUTION_HPP