Chris@16: //
Chris@16: // detail/chrono_time_traits.hpp
Chris@16: // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Chris@16: //
Chris@101: // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: 
Chris@16: #ifndef BOOST_ASIO_DETAIL_CHRONO_TIME_TRAITS_HPP
Chris@16: #define BOOST_ASIO_DETAIL_CHRONO_TIME_TRAITS_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: 
Chris@16: #include <boost/asio/detail/cstdint.hpp>
Chris@16: 
Chris@16: #include <boost/asio/detail/push_options.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace asio {
Chris@16: namespace detail {
Chris@16: 
Chris@101: // Helper template to compute the greatest common divisor.
Chris@101: template <int64_t v1, int64_t v2>
Chris@101: struct gcd { enum { value = gcd<v2, v1 % v2>::value }; };
Chris@101: 
Chris@101: template <int64_t v1>
Chris@101: struct gcd<v1, 0> { enum { value = v1 }; };
Chris@101: 
Chris@16: // Adapts std::chrono clocks for use with a deadline timer.
Chris@16: template <typename Clock, typename WaitTraits>
Chris@16: struct chrono_time_traits
Chris@16: {
Chris@16:   // The clock type.
Chris@16:   typedef Clock clock_type;
Chris@16: 
Chris@16:   // The duration type of the clock.
Chris@16:   typedef typename clock_type::duration duration_type;
Chris@16: 
Chris@16:   // The time point type of the clock.
Chris@16:   typedef typename clock_type::time_point time_type;
Chris@16: 
Chris@16:   // The period of the clock.
Chris@16:   typedef typename duration_type::period period_type;
Chris@16: 
Chris@16:   // Get the current time.
Chris@16:   static time_type now()
Chris@16:   {
Chris@16:     return clock_type::now();
Chris@16:   }
Chris@16: 
Chris@16:   // Add a duration to a time.
Chris@16:   static time_type add(const time_type& t, const duration_type& d)
Chris@16:   {
Chris@16:     const time_type epoch;
Chris@16:     if (t >= epoch)
Chris@16:     {
Chris@16:       if ((time_type::max)() - t < d)
Chris@16:         return (time_type::max)();
Chris@16:     }
Chris@16:     else // t < epoch
Chris@16:     {
Chris@16:       if (-(t - (time_type::min)()) > d)
Chris@16:         return (time_type::min)();
Chris@16:     }
Chris@16: 
Chris@16:     return t + d;
Chris@16:   }
Chris@16: 
Chris@16:   // Subtract one time from another.
Chris@16:   static duration_type subtract(const time_type& t1, const time_type& t2)
Chris@16:   {
Chris@16:     const time_type epoch;
Chris@16:     if (t1 >= epoch)
Chris@16:     {
Chris@16:       if (t2 >= epoch)
Chris@16:       {
Chris@16:         return t1 - t2;
Chris@16:       }
Chris@16:       else if (t2 == (time_type::min)())
Chris@16:       {
Chris@16:         return (duration_type::max)();
Chris@16:       }
Chris@16:       else if ((time_type::max)() - t1 < epoch - t2)
Chris@16:       {
Chris@16:         return (duration_type::max)();
Chris@16:       }
Chris@16:       else
Chris@16:       {
Chris@16:         return t1 - t2;
Chris@16:       }
Chris@16:     }
Chris@16:     else // t1 < epoch
Chris@16:     {
Chris@16:       if (t2 < epoch)
Chris@16:       {
Chris@16:         return t1 - t2;
Chris@16:       }
Chris@16:       else if (t1 == (time_type::min)())
Chris@16:       {
Chris@16:         return (duration_type::min)();
Chris@16:       }
Chris@16:       else if ((time_type::max)() - t2 < epoch - t1)
Chris@16:       {
Chris@16:         return (duration_type::min)();
Chris@16:       }
Chris@16:       else
Chris@16:       {
Chris@16:         return -(t2 - t1);
Chris@16:       }
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Test whether one time is less than another.
Chris@16:   static bool less_than(const time_type& t1, const time_type& t2)
Chris@16:   {
Chris@16:     return t1 < t2;
Chris@16:   }
Chris@16: 
Chris@16:   // Implement just enough of the posix_time::time_duration interface to supply
Chris@16:   // what the timer_queue requires.
Chris@16:   class posix_time_duration
Chris@16:   {
Chris@16:   public:
Chris@16:     explicit posix_time_duration(const duration_type& d)
Chris@16:       : d_(d)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     int64_t ticks() const
Chris@16:     {
Chris@16:       return d_.count();
Chris@16:     }
Chris@16: 
Chris@16:     int64_t total_seconds() const
Chris@16:     {
Chris@16:       return duration_cast<1, 1>();
Chris@16:     }
Chris@16: 
Chris@16:     int64_t total_milliseconds() const
Chris@16:     {
Chris@16:       return duration_cast<1, 1000>();
Chris@16:     }
Chris@16: 
Chris@16:     int64_t total_microseconds() const
Chris@16:     {
Chris@16:       return duration_cast<1, 1000000>();
Chris@16:     }
Chris@16: 
Chris@16:   private:
Chris@16:     template <int64_t Num, int64_t Den>
Chris@16:     int64_t duration_cast() const
Chris@16:     {
Chris@101:       const int64_t num1 = period_type::num / gcd<period_type::num, Num>::value;
Chris@101:       const int64_t num2 = Num / gcd<period_type::num, Num>::value;
Chris@101: 
Chris@101:       const int64_t den1 = period_type::den / gcd<period_type::den, Den>::value;
Chris@101:       const int64_t den2 = Den / gcd<period_type::den, Den>::value;
Chris@101: 
Chris@101:       const int64_t num = num1 * den2;
Chris@101:       const int64_t den = num2 * den1;
Chris@16: 
Chris@16:       if (num == 1 && den == 1)
Chris@16:         return ticks();
Chris@16:       else if (num != 1 && den == 1)
Chris@16:         return ticks() * num;
Chris@16:       else if (num == 1 && period_type::den != 1)
Chris@16:         return ticks() / den;
Chris@16:       else
Chris@16:         return ticks() * num / den;
Chris@16:     }
Chris@16: 
Chris@16:     duration_type d_;
Chris@16:   };
Chris@16: 
Chris@16:   // Convert to POSIX duration type.
Chris@16:   static posix_time_duration to_posix_duration(const duration_type& d)
Chris@16:   {
Chris@16:     return posix_time_duration(WaitTraits::to_wait_duration(d));
Chris@16:   }
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: } // namespace asio
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/asio/detail/pop_options.hpp>
Chris@16: 
Chris@16: #endif // BOOST_ASIO_DETAIL_CHRONO_TIME_TRAITS_HPP