Module epoch 

Conversion between broken-down civil time and the Unix epoch.

Receivers report the date and time of day as separate fields, and PROP_TIME carries one UINT32 second count, so something has to convert between them. Hosts need the same conversion in reverse to show an operator what the device thinks the time is.

The arithmetic is Howard Hinnant’s days-from-civil algorithm: integer only, no lookup tables, and correct for the whole proleptic Gregorian calendar rather than only for the years a leap-year table happens to cover.

Everything here is UTC. A local time-zone offset is presentation, applied by whatever is doing the presenting — see DateTime::shifted.

Structs

DateTime

A broken-down civil date and time, in UTC unless a caller has deliberately shifted it.

Constants

MAX_EPOCH

The largest second count u32 can express: 2106-02-07T06:28:15Z.

MIN_PLAUSIBLE_EPOCH

The earliest instant a receiver is believed: 2020-01-01T00:00:00Z.

Functions

civil_from_days

The proleptic Gregorian date days after 1970-01-01. The inverse of days_from_civil.

days_from_civil

Days since 1970-01-01 for a proleptic Gregorian date.

days_in_month

Days in month of year, 1-indexed. Zero for an out-of-range month, which makes an invalid month fail the day check in DateTime::is_valid rather than needing its own branch.

is_leap_year

The proleptic Gregorian leap-year rule.