Chris@16: //  mac/chrono.cpp  --------------------------------------------------------------//
Chris@16: 
Chris@16: //  Copyright Beman Dawes 2008
Chris@16: //  Copyright 2009-2010 Vicente J. Botet Escriba
Chris@16: 
Chris@16: //  Distributed under the Boost Software License, Version 1.0.
Chris@16: //  See http://www.boost.org/LICENSE_1_0.txt
Chris@16: 
Chris@16: 
Chris@16: //----------------------------------------------------------------------------//
Chris@16: //                                 Mac                                        //
Chris@16: //----------------------------------------------------------------------------//
Chris@16: 
Chris@16: #include <sys/time.h> //for gettimeofday and timeval
Chris@16: #include <mach/mach_time.h>  // mach_absolute_time, mach_timebase_info_data_t
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16: namespace chrono
Chris@16: {
Chris@16: 
Chris@16: // system_clock
Chris@16: 
Chris@16: // gettimeofday is the most precise "system time" available on this platform.
Chris@16: // It returns the number of microseconds since New Years 1970 in a struct called timeval
Chris@16: // which has a field for seconds and a field for microseconds.
Chris@16: //    Fill in the timeval and then convert that to the time_point
Chris@16: system_clock::time_point
Chris@16: system_clock::now() BOOST_NOEXCEPT
Chris@16: {
Chris@16:     timeval tv;
Chris@16:     gettimeofday(&tv, 0);
Chris@16:     return time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec));
Chris@16: }
Chris@16: 
Chris@16: #if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING
Chris@16: system_clock::time_point
Chris@16: system_clock::now(system::error_code & ec)
Chris@16: {
Chris@16:     timeval tv;
Chris@16:     gettimeofday(&tv, 0);
Chris@16:     if (!BOOST_CHRONO_IS_THROWS(ec)) 
Chris@16:     {
Chris@16:         ec.clear();
Chris@16:     }
Chris@16:     return time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec));
Chris@16: }
Chris@16: #endif
Chris@16: // Take advantage of the fact that on this platform time_t is nothing but
Chris@16: //    an integral count of seconds since New Years 1970 (same epoch as timeval).
Chris@16: //    Just get the duration out of the time_point and truncate it to seconds.
Chris@16: time_t
Chris@16: system_clock::to_time_t(const time_point& t) BOOST_NOEXCEPT
Chris@16: {
Chris@16:     return time_t(duration_cast<seconds>(t.time_since_epoch()).count());
Chris@16: }
Chris@16: 
Chris@16: // Just turn the time_t into a count of seconds and construct a time_point with it.
Chris@16: system_clock::time_point
Chris@16: system_clock::from_time_t(time_t t) BOOST_NOEXCEPT
Chris@16: {
Chris@16:     return system_clock::time_point(seconds(t));
Chris@16: }
Chris@16: 
Chris@16: namespace chrono_detail
Chris@16: {
Chris@16: 
Chris@16: // steady_clock
Chris@16: 
Chris@16: // Note, in this implementation steady_clock and high_resolution_clock
Chris@16: //   are the same clock.  They are both based on mach_absolute_time().
Chris@16: //   mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of
Chris@16: //   nanoseconds since the computer booted up.  MachInfo.numer and MachInfo.denom
Chris@16: //   are run time constants supplied by the OS.  This clock has no relationship
Chris@16: //   to the Gregorian calendar.  It's main use is as a high resolution timer.
Chris@16: 
Chris@16: // MachInfo.numer / MachInfo.denom is often 1 on the latest equipment.  Specialize
Chris@16: //   for that case as an optimization.
Chris@16: BOOST_CHRONO_STATIC
Chris@16: steady_clock::rep
Chris@16: steady_simplified()
Chris@16: {
Chris@16:     return mach_absolute_time();
Chris@16: }
Chris@16: 
Chris@16: #if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING
Chris@16: BOOST_CHRONO_STATIC
Chris@16: steady_clock::rep
Chris@16: steady_simplified_ec(system::error_code & ec)
Chris@16: {
Chris@16:     if (!BOOST_CHRONO_IS_THROWS(ec)) 
Chris@16:     {
Chris@16:         ec.clear();
Chris@16:     }
Chris@16:     return mach_absolute_time();
Chris@16: }
Chris@16: #endif
Chris@16: 
Chris@16: BOOST_CHRONO_STATIC
Chris@16: double
Chris@16: compute_steady_factor(kern_return_t& err)
Chris@16: {
Chris@16:     mach_timebase_info_data_t MachInfo;
Chris@16:     err = mach_timebase_info(&MachInfo);
Chris@16:     if ( err != 0  ) {
Chris@16:         return 0;
Chris@16:     }
Chris@16:     return static_cast<double>(MachInfo.numer) / MachInfo.denom;
Chris@16: }
Chris@16: 
Chris@16: BOOST_CHRONO_STATIC
Chris@16: steady_clock::rep
Chris@16: steady_full()
Chris@16: {
Chris@16:     static kern_return_t err;
Chris@16:     static const double factor = chrono_detail::compute_steady_factor(err);
Chris@16:     if (err != 0) 
Chris@16:     {
Chris@16:       BOOST_ASSERT(0 && "Boost::Chrono - Internal Error");
Chris@16:     }
Chris@16:     return static_cast<steady_clock::rep>(mach_absolute_time() * factor);
Chris@16: }
Chris@16: 
Chris@16: #if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING
Chris@16: BOOST_CHRONO_STATIC
Chris@16: steady_clock::rep
Chris@16: steady_full_ec(system::error_code & ec)
Chris@16: {
Chris@16:     static kern_return_t err;
Chris@16:     static const double factor = chrono_detail::compute_steady_factor(err);
Chris@16:     if (err != 0) 
Chris@16:     {
Chris@16:         if (BOOST_CHRONO_IS_THROWS(ec))
Chris@16:         {
Chris@16:             boost::throw_exception(
Chris@16:                     system::system_error( 
Chris@16:                             err, 
Chris@16:                             BOOST_CHRONO_SYSTEM_CATEGORY, 
Chris@16:                             "chrono::steady_clock" ));
Chris@16:         } 
Chris@16:         else
Chris@16:         {
Chris@16:             ec.assign( errno, BOOST_CHRONO_SYSTEM_CATEGORY );
Chris@16:             return steady_clock::rep();
Chris@16:         }
Chris@16:     }
Chris@16:     if (!BOOST_CHRONO_IS_THROWS(ec)) 
Chris@16:     {
Chris@16:         ec.clear();
Chris@16:     }
Chris@16:     return static_cast<steady_clock::rep>(mach_absolute_time() * factor);
Chris@16: }
Chris@16: #endif
Chris@16: 
Chris@16: typedef steady_clock::rep (*FP)();
Chris@16: #if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING
Chris@16: typedef steady_clock::rep (*FP_ec)(system::error_code &);
Chris@16: #endif
Chris@16: 
Chris@16: BOOST_CHRONO_STATIC
Chris@16: FP
Chris@16: init_steady_clock(kern_return_t & err)
Chris@16: {
Chris@16:     mach_timebase_info_data_t MachInfo;
Chris@16:     err = mach_timebase_info(&MachInfo);
Chris@16:     if ( err != 0  ) 
Chris@16:     {
Chris@16:         return 0;
Chris@16:     }
Chris@16: 
Chris@16:     if (MachInfo.numer == MachInfo.denom)
Chris@16:     {
Chris@16:         return &chrono_detail::steady_simplified;
Chris@16:     }
Chris@16:     return &chrono_detail::steady_full;
Chris@16: }
Chris@16: 
Chris@16: #if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING
Chris@16: BOOST_CHRONO_STATIC
Chris@16: FP_ec
Chris@16: init_steady_clock_ec(kern_return_t & err)
Chris@16: {
Chris@16:     mach_timebase_info_data_t MachInfo;
Chris@16:     err = mach_timebase_info(&MachInfo);
Chris@16:     if ( err != 0  ) 
Chris@16:     {
Chris@16:         return 0;
Chris@16:     }
Chris@16: 
Chris@16:     if (MachInfo.numer == MachInfo.denom) 
Chris@16:     {
Chris@16:         return &chrono_detail::steady_simplified_ec;
Chris@16:     }
Chris@16:     return &chrono_detail::steady_full_ec;
Chris@16: }
Chris@16: #endif
Chris@16: }
Chris@16: 
Chris@16: steady_clock::time_point
Chris@16: steady_clock::now() BOOST_NOEXCEPT
Chris@16: {
Chris@16:     static kern_return_t err;
Chris@16:     static chrono_detail::FP fp = chrono_detail::init_steady_clock(err);
Chris@16:     if ( err != 0  ) 
Chris@16:     {     
Chris@16:       BOOST_ASSERT(0 && "Boost::Chrono - Internal Error");
Chris@16:     }
Chris@16:     return time_point(duration(fp()));
Chris@16: }
Chris@16: 
Chris@16: #if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING
Chris@16: steady_clock::time_point
Chris@16: steady_clock::now(system::error_code & ec)
Chris@16: {
Chris@16:     static kern_return_t err;
Chris@16:     static chrono_detail::FP_ec fp = chrono_detail::init_steady_clock_ec(err);
Chris@16:     if ( err != 0  ) 
Chris@16:     {
Chris@16:         if (BOOST_CHRONO_IS_THROWS(ec))
Chris@16:         {
Chris@16:             boost::throw_exception(
Chris@16:                     system::system_error( 
Chris@16:                             err, 
Chris@16:                             BOOST_CHRONO_SYSTEM_CATEGORY, 
Chris@16:                             "chrono::steady_clock" ));
Chris@16:         }
Chris@16:         else
Chris@16:         {
Chris@16:             ec.assign( err, BOOST_CHRONO_SYSTEM_CATEGORY );
Chris@16:             return time_point();
Chris@16:         }
Chris@16:     }
Chris@16:     if (!BOOST_CHRONO_IS_THROWS(ec)) 
Chris@16:     {
Chris@16:         ec.clear();
Chris@16:     }
Chris@16:     return time_point(duration(fp(ec)));
Chris@16: }
Chris@16: #endif
Chris@16: }  // namespace chrono
Chris@16: }  // namespace boost