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author | theraven <theraven@FreeBSD.org> | 2011-11-22 17:30:41 +0000 |
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committer | theraven <theraven@FreeBSD.org> | 2011-11-22 17:30:41 +0000 |
commit | d8f28ec8a2faabad3aabb9f7a26755971424ef05 (patch) | |
tree | 5c73f10d9b3740138364680a74334d50b222cd6d /src/chrono.cpp | |
download | FreeBSD-src-d8f28ec8a2faabad3aabb9f7a26755971424ef05.zip FreeBSD-src-d8f28ec8a2faabad3aabb9f7a26755971424ef05.tar.gz |
Import libcxxrt / libc++ into a vendor branch.
Approved by: dim (mentor)
Diffstat (limited to 'src/chrono.cpp')
-rw-r--r-- | src/chrono.cpp | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/src/chrono.cpp b/src/chrono.cpp new file mode 100644 index 0000000..416b950 --- /dev/null +++ b/src/chrono.cpp @@ -0,0 +1,128 @@ +//===------------------------- chrono.cpp ---------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "chrono" +#include <sys/time.h> //for gettimeofday and timeval +#if __APPLE__ +#include <mach/mach_time.h> // mach_absolute_time, mach_timebase_info_data_t +#else /* !__APPLE__ */ +#include <cerrno> // errno +#include <system_error> // __throw_system_error +#include <time.h> // clock_gettime, CLOCK_MONOTONIC +#endif // __APPLE__ + +_LIBCPP_BEGIN_NAMESPACE_STD + +namespace chrono +{ + +// system_clock + +system_clock::time_point +system_clock::now() _NOEXCEPT +{ + timeval tv; + gettimeofday(&tv, 0); + return time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec)); +} + +time_t +system_clock::to_time_t(const time_point& t) _NOEXCEPT +{ + return time_t(duration_cast<seconds>(t.time_since_epoch()).count()); +} + +system_clock::time_point +system_clock::from_time_t(time_t t) _NOEXCEPT +{ + return system_clock::time_point(seconds(t)); +} + +// steady_clock + +#if __APPLE__ +// mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of +// nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom +// are run time constants supplied by the OS. This clock has no relationship +// to the Gregorian calendar. It's main use is as a high resolution timer. + +// MachInfo.numer / MachInfo.denom is often 1 on the latest equipment. Specialize +// for that case as an optimization. + +#pragma GCC visibility push(hidden) + +static +steady_clock::rep +steady_simplified() +{ + return mach_absolute_time(); +} + +static +double +compute_steady_factor() +{ + mach_timebase_info_data_t MachInfo; + mach_timebase_info(&MachInfo); + return static_cast<double>(MachInfo.numer) / MachInfo.denom; +} + +static +steady_clock::rep +steady_full() +{ + static const double factor = compute_steady_factor(); + return static_cast<steady_clock::rep>(mach_absolute_time() * factor); +} + +typedef steady_clock::rep (*FP)(); + +static +FP +init_steady_clock() +{ + mach_timebase_info_data_t MachInfo; + mach_timebase_info(&MachInfo); + if (MachInfo.numer == MachInfo.denom) + return &steady_simplified; + return &steady_full; +} + +#pragma GCC visibility pop + +steady_clock::time_point +steady_clock::now() _NOEXCEPT +{ + static FP fp = init_steady_clock(); + return time_point(duration(fp())); +} + +#else // __APPLE__ +// FIXME: We assume that clock_gettime(CLOCK_MONOTONIC) works on +// non-apple systems. Instead, we should check _POSIX_TIMERS and +// _POSIX_MONOTONIC_CLOCK and fall back to something else if those +// don't exist. + +// Warning: If this is not truly steady, then it is non-conforming. It is +// better for it to not exist and have the rest of libc++ use system_clock +// instead. + +steady_clock::time_point +steady_clock::now() _NOEXCEPT +{ + struct timespec tp; + if (0 != clock_gettime(CLOCK_MONOTONIC, &tp)) + __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed"); + return time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); +} +#endif // __APPLE__ + +} + +_LIBCPP_END_NAMESPACE_STD |