This ensures use of the Time Tool is fully under the control of the programmer, rather than potentially being affected by other things that may load it (like the Time Zone CDev). It also avoids calls to tiStatus in the default non-Time Tool code paths, and thereby allows them to work under Golden Gate.
The UTC time may be several hours before or after local time, and therefore the UTC time/date may be slightly outside the limits of what can be represented as a local time/date. This is now handled correctly.
This also more generally fixes handling of negative seconds/minutes/hours, which is also applicable to mktime().
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.
It was clearly supposed to be 1 Jan 1970, but it's actually not, probably because the number of days from 1 Jan 1900 to 1 Jan 1970 was miscalculated. Changing it now could potentially cause compatibility issues (especially for GNO, which uses time_t in some kernel call interfaces and file formats), so for now it is left as is and just documented appropriately.
Nothing in the C standards requires the time_t epoch to be 1 Jan 1970, so this does not cause any standards-compliance problem for the C standards. (It is different from POSIX, though.)
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.
Tabs have been expanded to spaces in several files that use mainly spaces for indentation.
The files ctype.asm, stdio.asm, and string.asm consistently use tabs for indentation. The tabs in these files have been left alone, except that a few tabs between sentences in comments were changed to spaces. One space-indented line in stdio.asm was changed to use a tab.
This could happen when it was called for a time other than the present, because it set tm_isdst based on the current value of the DST flag in BRAM, which is valid only for the current time.
Now it works as follows: If localtime() is passed the time_t value that was produced by the most recent call to time(), it gives the DST setting in effect at the time of that call. Otherwise, it sets tm_isdst to -1, indicating that the correct value is unknown.
This is about the best we can do without having a full timezone library/database. It should give the right tm_isdst value in probably the most common case, and avoids giving an incorrect value in any case (assuming the system's DST flag is right).
This fixes#18.
