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