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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___CHRONO_GPS_CLOCK_H11#define _LIBCPP___CHRONO_GPS_CLOCK_H12 13#include <version>14// Enable the contents of the header only when libc++ was built with experimental features enabled.15#if _LIBCPP_HAS_EXPERIMENTAL_TZDB16 17# include <__assert>18# include <__chrono/duration.h>19# include <__chrono/time_point.h>20# include <__chrono/utc_clock.h>21# include <__config>22# include <__type_traits/common_type.h>23 24# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)25# pragma GCC system_header26# endif27 28_LIBCPP_PUSH_MACROS29# include <__undef_macros>30 31_LIBCPP_BEGIN_NAMESPACE_STD32 33# if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION34 35namespace chrono {36 37class gps_clock;38 39template <class _Duration>40using gps_time = time_point<gps_clock, _Duration>;41using gps_seconds = gps_time<seconds>;42 43class gps_clock {44public:45 using rep = utc_clock::rep;46 using period = utc_clock::period;47 using duration = chrono::duration<rep, period>;48 using time_point = chrono::time_point<gps_clock>;49 static constexpr bool is_steady = false; // The utc_clock is not steady.50 51 // The static difference between UTC and GPS time as specified in the Standard.52 static constexpr chrono::seconds __offset{315964809};53 54 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static time_point now() { return from_utc(utc_clock::now()); }55 56 template <class _Duration>57 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static utc_time<common_type_t<_Duration, seconds>>58 to_utc(const gps_time<_Duration>& __time) noexcept {59 using _Rp = common_type_t<_Duration, seconds>;60 _Duration __time_since_epoch = __time.time_since_epoch();61 _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(__time_since_epoch >= utc_time<_Rp>::min().time_since_epoch() + __offset,62 "the GPS to UTC conversion would underflow");63 64 return utc_time<_Rp>{__time_since_epoch + __offset};65 }66 67 template <class _Duration>68 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static gps_time<common_type_t<_Duration, seconds>>69 from_utc(const utc_time<_Duration>& __time) noexcept {70 using _Rp = common_type_t<_Duration, seconds>;71 _Duration __time_since_epoch = __time.time_since_epoch();72 _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(__time_since_epoch <= utc_time<_Rp>::max().time_since_epoch() - __offset,73 "the UTC to GPS conversion would overflow");74 75 return gps_time<_Rp>{__time_since_epoch - __offset};76 }77};78 79} // namespace chrono80 81# endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&82 // _LIBCPP_HAS_LOCALIZATION83 84_LIBCPP_END_NAMESPACE_STD85 86_LIBCPP_POP_MACROS87 88#endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB89 90#endif // _LIBCPP___CHRONO_GPS_CLOCK_H91