μ time zone (library)

An embedded timezone library and ~3kB tzinfo database featuring nearly all current timezones present in the IANA timezone database. Designed for use on budget embedded systems with low program space.

The C header containing packed timezone information is generated from the IANA timezone database.

Tradeoffs

All historical timezone information has been pruned to save space.

A limited number of aliases are available. (by default restricted to the same set that android uses) In cases where the alias is not available, the standard time UTC offset and abbreviation (if present) will be displayed.

This library is generally inflexible as it heavily relies on assumptions pertaining to timezone offset increments, abbreviation formatting, etc to make efficient use of bit packs.

Limitations

The current utility library does not support parsing / packing all possible syntax of the source IANA tz database. Instead a subset corresponding to the what is needed to correctly parse most zones is implemented.

Links

zic man page and IANA tz database format documentation

vendored files

Instructions to generate files (without Make)

1. Setup dev environment: python3 -m pip install -r requirements.txt
2. Generate links based on major cities: python3 utils/compile_tzlinks.py
3. Generate a list of timezones to include, based on major cities and timezones included in Android: python3 utils/compile_whitelist.py
4. Generate zones.h and zones.c: python3 utils/generate_zones.py -d vendor/tzdata -r africa -r asia -r australasia -r backward -r europe -r northamerica -r pacificnew -r southamerica -w whitelist.txt -i majorcities

Include different regions in step 5 based on your preferences

Updating the TZ Database

To update the tzdatabase replace the files in vendor/tzdata with that of the following link: https://www.iana.org/time-zones Use the data only distribution

Should make this an automatic process via GitHub actions (Possible Feature).