25 Time library [time]

25.7 Clocks [time.clock]

25.7.4 Class gps_­clock [time.clock.gps]

25.7.4.2 Member functions [time.clock.gps.members]

static time_point now();
Returns: from_­utc(utc_­clock::now()), or a more accurate value of gps_­time.
template<class Duration> static utc_time<common_type_t<Duration, seconds>> to_utc(const gps_time<Duration>& t) noexcept;
Returns:
gps_time<common_type_t<Duration, seconds>>{t.time_since_epoch()} + 315964809s
[Note
:
315964809s == sys_days{1980y/January/Sunday[1]} - sys_days{1970y/January/1} + 9s
end note
]
template<class Duration> static gps_time<common_type_t<Duration, seconds>> from_utc(const utc_time<Duration>& t) noexcept;
Returns:
gps_time<common_type_t<Duration, seconds>>{t.time_since_epoch()} - 315964809s
[Note
:
315964809s == sys_days{1980y/January/Sunday[1]} - sys_days{1970y/January/1} + 9s
end note
]