🚀 go-pugleaf

Hello,

In article <csgr.674122345@alpha> csgr@alpha.cs.ru.ac.za (Geoff Rehmet) writes:
>I am at the moment looking into porting the PX-XINU sources to the
>80286 running in protected mode, with the intention of making use
>of the 286's hardware task management and memory protection features.
>
>A major problem which I forsee is in compiling the XINU C sources, as
>I do not have a C compiler available for the 80286.  (The main problem
>is that existing C compilers generate code which will run fine in real mode
>but which does not handle the 286's memory management features - resulting
>in problems with segment references.)
It's possible to do a port of PC-XINU into 80286 protected mode without
special C-compilers. I did a port of PC-XINU Version 6 with Turbo-C V2.0.
But: I did it only in small-memory model, no large-memory version. I
also used the hardware task management and some of the memory protection
features available by the 80286.

>(I have thought of tricks such as modifying the objects and executables
>generated by existing DOS C compilers, such as Turbo C, but I would like
>to try and find a cleaner method.)
No special tricks were needed for the port, just some thoughts.

You have to compile all the C sources in Turbo-C's tiny model and link
it with the small memory startup-code to get enough memory. You HAVE
to compile in tiny model, because Turbo-C calls some runtime-routines
with a "jmp far xxx". In tiny model Turbo-C uses the following sequence:

	push	cs
	call	near <routine>

With Turbo-C++ this trick won't help because Borland did another
trick in their runtime library.

Sorry for my bad english, but perhaps I could help you. For more
questions just contact me by email.

Ciao
	Andreas
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* Andreas Stuebinger	Rosstraenke 9	D-8390 Passau	**49-851-35600	*
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