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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-exception |
| 7 | +// |
| 8 | +//===----------------------------------------------------------------------===// |
| 9 | + |
| 10 | +#ifndef _LIBCPP___CHRONO_GPS_CLOCK_H |
| 11 | +#define _LIBCPP___CHRONO_GPS_CLOCK_H |
| 12 | + |
| 13 | +#include <version> |
| 14 | +// Enable the contents of the header only when libc++ was built with experimental features enabled. |
| 15 | +#if _LIBCPP_HAS_EXPERIMENTAL_TZDB |
| 16 | + |
| 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_header |
| 26 | +# endif |
| 27 | + |
| 28 | +_LIBCPP_PUSH_MACROS |
| 29 | +# include <__undef_macros> |
| 30 | + |
| 31 | +_LIBCPP_BEGIN_NAMESPACE_STD |
| 32 | + |
| 33 | +# if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION |
| 34 | + |
| 35 | +namespace chrono { |
| 36 | + |
| 37 | +class gps_clock; |
| 38 | + |
| 39 | +template <class _Duration> |
| 40 | +using gps_time = time_point<gps_clock, _Duration>; |
| 41 | +using gps_seconds = gps_time<seconds>; |
| 42 | + |
| 43 | +class gps_clock { |
| 44 | +public: |
| 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 chrono |
| 80 | + |
| 81 | +# endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && |
| 82 | + // _LIBCPP_HAS_LOCALIZATION |
| 83 | + |
| 84 | +_LIBCPP_END_NAMESPACE_STD |
| 85 | + |
| 86 | +_LIBCPP_POP_MACROS |
| 87 | + |
| 88 | +#endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB |
| 89 | + |
| 90 | +#endif // _LIBCPP___CHRONO_GPS_CLOCK_H |
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