From: "KECSKEMÉTI BALÁZS" <balazs AT tiszanet DOT hu>
Newsgroups: comp.os.msdos.djgpp
Subject: a bunch of not so newbie questions ( i think )
Date: Sun, 8 Nov 1998 12:53:27 +0100
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Jo everybody!

I really hate posting questions to newsgroups, but
now I have some that I couldn't find in the FAQ's.
They are related to external assembly programming
with DJGPP (NASM).

1) What's in the segment registers under DJGPP?
I guess that there is a constant value, because i
measured that pointers under DJGPP are 32 bits.

2) If i allocate some (DOS) memory in an external assembly
function, then how do i access it in the C program? As i pointed
out in 1), DJGPP pointers don't contain the selector, just the
offset and DPMI function 100h gives me a just a single selector.

These are important questions for me beacuse my very
first external asm function generates a nasty page fault.
Anyway, what's a page fault _exactly? What are the possible
causes of it? I used to program in real mode assembly and
pascal for some time, and i thought that it's the time for changing
to pmode asm and C, but now i'm a bit confused with
selectors, physical and linear addresses, page faults etc.
(Altough i've read lots of tutorials on PMODE)
So if u can please answer my questions.

Thanks
Balazs Kecskemeti
balazs AT tiszanet DOT hu