these symbols are in LGROUP and generaly cannot be addressed by DGROUP:offset
for Turbo C DGROUP offset overflow because symbols are too far to be addressed by DGROUP offset
- fix issue by renaming header file and symbols which consolidate with standard C time.h
- rename also date.h for consistency
- remove all hacks from make files and from sys.c
now can share new dtime.h with standard C time.h without any collision that any order of internal and standard C header path is possible
lDebug wants to access the environment while executing
as a device driver. Instead of building it in a variable
then copying it to 68h:0 after FDCONFIG.SYS processing,
just build it there to begin with.
Some assembly tricks:
* SMC instead of checking the XMS driver address
in the DOS DS stub,
* SMC so that the address goes right into a
`call far immediate` instruction,
* use `repe cmpsw` to compare multiple words (saves
space over the individual word compares),
* near calls to far functions use push cs to build
a far-call stack frame,
* segments 0 and FFFFh generated by segment arithmetic
instead of loading from memory,
* common case (A20 already enabled) made to be the case
where the conditional branch just falls through, which
may be slightly better.
Using DOSTEXT(x) accesses x in LGROUP and DOSDATA(x) in DGROUP.
This is necessary since ia16-elf-gcc does not understand data
in far segments.
For non-macro'ed symbols, FP_SEG needs to be replaced by explicit
segment references.
