Message-ID:	<37533A3A.B6A84588@hitech.net.au>
From:	leroy <leroy AT hitech DOT net DOT au>
X-Mailer:	Mozilla 4.5 [en] (Win98; I)
X-Accept-Language:	en,ja
MIME-Version:	1.0
Newsgroups:	comp.os.msdos.djgpp
Subject:	DJGPP - real mode procedures.
Lines:	50
Date:	Tue, 01 Jun 1999 11:41:15 +1000
NNTP-Posting-Host:	203.27.197.43
X-Complaints-To:	abuse AT telstra DOT net
X-Trace:	nswpull.telstra.net 928201636 203.27.197.43 (Tue, 01 Jun 1999 11:47:16 EST)
NNTP-Posting-Date:	Tue, 01 Jun 1999 11:47:16 EST
Organization:	Customer of Telstra Big Pond Direct
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

I've found some strange anomolies when calling a real mode procedure in
DJGPP.

Tell me if this is the wrong way to do things.

unsigned char *code[] = {0x5b, 0xb8, 0x10, 0x00, 0x01, 0xd8, 0xcf};

According to debug that is
pop bx
mov ax, 10
add ax, bx
iret

Now, I allocate dos memory using the dpmi function, allocating 1 more
paragraph than I need (just for safety).

I move the code to that allocated memory using the dosmemput() routine.
I checked using _farpokeb() routines that the transfer worked.

I set up the registers using
__dpmi_regs r;
r.x.ss = 0; r.x.sp = 0;
r.x.cs = seg; // the value returned from the dos allocation routine
r.x.ip = 0;

I have a variable called stack that is initialised like so
int stack[] = {0x10};

I then call the function
__dpmi_simulate_real_mode_procedure_retf_stack(&r, 4, &stack);

I'm not so sure how the values for the stack should be passed, so I did
some assumed values, like 4.  Is this right?

Next thing was that when this is run, Windows says that an illegal
instruction was encountered.

It did this even when I ran a smaller procedure that was this
mov ax, 13
retf

When I changed the retf to an iret it worked.

Any ideas what's wrong?

Cheers,

leroy.

- Raw text -