| // chrono.hpp --------------------------------------------------------------// |
| |
| // Copyright 2008 Howard Hinnant |
| // Copyright 2008 Beman Dawes |
| // Copyright 2009-2010 Vicente J. Botet Escriba |
| |
| // Distributed under the Boost Software License, Version 1.0. |
| // See http://www.boost.org/LICENSE_1_0.txt |
| |
| /* |
| |
| This code was derived by Beman Dawes from Howard Hinnant's time2_demo prototype. |
| Many thanks to Howard for making his code available under the Boost license. |
| The original code was modified to conform to Boost conventions and to section |
| 20.9 Time utilities [time] of the C++ committee's working paper N2798. |
| See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2798.pdf. |
| |
| time2_demo contained this comment: |
| |
| Much thanks to Andrei Alexandrescu, |
| Walter Brown, |
| Peter Dimov, |
| Jeff Garland, |
| Terry Golubiewski, |
| Daniel Krugler, |
| Anthony Williams. |
| */ |
| |
| /* |
| |
| TODO: |
| |
| * Fully implement error handling, with test cases. |
| * Use boost::throw_exception. (Currently not used because of an issue with Intel 11.0.) |
| * Consider issues raised by Michael Marcin: |
| |
| > In the past I've seen QueryPerformanceCounter give incorrect results, |
| > especially with SpeedStep processors on laptops. This was many years ago and |
| > might have been fixed by service packs and drivers. |
| > |
| > Typically you check the results of QPC against GetTickCount to see if the |
| > results are reasonable. |
| > http://support.microsoft.com/kb/274323 |
| > |
| > I've also heard of problems with QueryPerformanceCounter in multi-processor |
| > systems. |
| > |
| > I know some people SetThreadAffinityMask to 1 for the current thread call |
| > their QueryPerformance* functions then restore SetThreadAffinityMask. This |
| > seems horrible to me because it forces your program to jump to another |
| > physical processor if it isn't already on cpu0 but they claim it worked well |
| > in practice because they called the timing functions infrequently. |
| > |
| > In the past I have chosen to use timeGetTime with timeBeginPeriod(1) for |
| > high resolution timers to avoid these issues. |
| |
| */ |
| |
| #ifndef BOOST_CHRONO_SYSTEM_CLOCKS_HPP |
| #define BOOST_CHRONO_SYSTEM_CLOCKS_HPP |
| |
| #include <boost/chrono/config.hpp> |
| #include <boost/chrono/duration.hpp> |
| #include <boost/chrono/time_point.hpp> |
| #include <boost/chrono/detail/system.hpp> |
| #include <boost/system/error_code.hpp> |
| |
| #include <ctime> |
| |
| #ifdef BOOST_CHRONO_WINDOWS_API |
| // The system_clock tick is 100 nanoseconds |
| # define BOOST_SYSTEM_CLOCK_DURATION boost::chrono::duration<boost::int_least64_t, ratio<BOOST_RATIO_INTMAX_C(1), BOOST_RATIO_INTMAX_C(10000000)> > |
| #else |
| # define BOOST_SYSTEM_CLOCK_DURATION boost::chrono::nanoseconds |
| #endif |
| |
| #ifndef BOOST_CHRONO_HEADER_ONLY |
| #include <boost/config/abi_prefix.hpp> // must be the last #include |
| #endif |
| |
| |
| //----------------------------------------------------------------------------// |
| // // |
| // 20.9 Time utilities [time] // |
| // synopsis // |
| // // |
| //----------------------------------------------------------------------------// |
| |
| namespace boost { |
| namespace chrono { |
| |
| // Clocks |
| class BOOST_CHRONO_DECL system_clock; |
| #ifdef BOOST_CHRONO_HAS_CLOCK_STEADY |
| class BOOST_CHRONO_DECL steady_clock; // as permitted by [time.clock.steady] |
| #endif |
| |
| #ifdef BOOST_CHRONO_HAS_CLOCK_STEADY |
| typedef steady_clock high_resolution_clock; // as permitted by [time.clock.hires] |
| #else |
| typedef system_clock high_resolution_clock; // as permitted by [time.clock.hires] |
| #endif |
| |
| //----------------------------------------------------------------------------// |
| // // |
| // 20.9.5 Clocks [time.clock] // |
| // // |
| //----------------------------------------------------------------------------// |
| |
| // If you're porting, clocks are the system-specific (non-portable) part. |
| // You'll need to know how to get the current time and implement that under now(). |
| // You'll need to know what units (tick period) and representation makes the most |
| // sense for your clock and set those accordingly. |
| // If you know how to map this clock to time_t (perhaps your clock is std::time, which |
| // makes that trivial), then you can fill out system_clock's to_time_t() and from_time_t(). |
| |
| //----------------------------------------------------------------------------// |
| // 20.9.5.1 Class system_clock [time.clock.system] // |
| //----------------------------------------------------------------------------// |
| |
| class BOOST_CHRONO_DECL system_clock |
| { |
| public: |
| typedef BOOST_SYSTEM_CLOCK_DURATION duration; |
| typedef duration::rep rep; |
| typedef duration::period period; |
| typedef chrono::time_point<system_clock> time_point; |
| BOOST_CHRONO_STATIC_CONSTEXPR bool is_steady = false; |
| |
| static BOOST_CHRONO_INLINE time_point now(); // throws on error |
| static BOOST_CHRONO_INLINE time_point now(system::error_code & ec); // never throws |
| |
| static BOOST_CHRONO_INLINE std::time_t to_time_t(const time_point& t); |
| static BOOST_CHRONO_INLINE time_point from_time_t(std::time_t t); |
| }; |
| |
| //----------------------------------------------------------------------------// |
| // 20.9.5.2 Class steady_clock [time.clock.steady] // |
| //----------------------------------------------------------------------------// |
| |
| // As permitted by [time.clock.steady] |
| // The class steady_clock is conditionally supported. |
| |
| #ifdef BOOST_CHRONO_HAS_CLOCK_STEADY |
| class BOOST_CHRONO_DECL steady_clock |
| { |
| public: |
| typedef nanoseconds duration; |
| typedef duration::rep rep; |
| typedef duration::period period; |
| typedef chrono::time_point<steady_clock> time_point; |
| BOOST_CHRONO_STATIC_CONSTEXPR bool is_steady = true; |
| |
| static BOOST_CHRONO_INLINE time_point now(); // throws on error |
| static BOOST_CHRONO_INLINE time_point now(system::error_code & ec); // never throws |
| }; |
| #endif |
| //----------------------------------------------------------------------------// |
| // 20.9.5.3 Class high_resolution_clock [time.clock.hires] // |
| //----------------------------------------------------------------------------// |
| |
| // As permitted, steady_clock or system_clock is a typedef for high_resolution_clock. |
| // See synopsis. |
| |
| |
| } // namespace chrono |
| } // namespace boost |
| |
| #ifndef BOOST_CHRONO_HEADER_ONLY |
| #include <boost/config/abi_suffix.hpp> // pops abi_prefix.hpp pragmas |
| #else |
| #include <boost/chrono/detail/inlined/chrono.hpp> |
| #endif |
| |
| #endif // BOOST_CHRONO_SYSTEM_CLOCKS_HPP |
