ORCA/C uses an unsigned 32-bit time_t which should give a range up to 2105, but calculations on it were being done with signed types, causing them not to work correctly beyond 2036-2038. Now the factor routine, mktime(), and time() should work up to 2105. (In the case of time(), this assumes ReadTimeHex reports the time correctly.)
The factor routine actually computes a 64-bit time value. Currently, the rest of the code only takes the bottom 32 bits of it, but this could be extended if we ever wanted to switch to 64-bit time_t.
This is used for the %z conversion specifier (giving the time zone offset in +-HHMM format). The %Z conversion specifier (giving the locale's time zone name or abbreviation) also prints the same thing for now.
As with gmtime, this will only use the Time Tool Set if it has already been started. Otherwise, these conversions simply produce no output.
If the Time Tool Set (tool 56, by Geoff Weiss) is present and active, gmtime will use it (plus the DST flag) to determine the local time offset from UTC, allowing it to produce the correct UTC time. If not, it will still treat local time as being equal to UTC, like it did previously.
The library code will not try to load or start the Time Tool Set, so the program will have to do that before calling gmtime if it wants to use this functionality.
This is intended to be a complete implementation of strftime as specified in C17, although it lacks meaningful support for time zones or non-C locales.
This may be either 50 or 60, depending on the system's video frequency setting (50Hz PAL or 60Hz NTSC). The video setting can be determined by inspecting bit 4 of the LANGSEL soft switch, documented in Appendix E of the Apple IIGS Firmware Reference.
Stephen Heumann
Kelvin Sherlock
mikew50