From:	DavMac AT iname DOT com (Davin McCall)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: DJGPP - real mode procedures.
Date:	Tue, 01 Jun 1999 05:52:40 GMT
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I didn't give the code a major going over or anything, but did see one
or two things I thought could cause a problem:

>pop bx
>mov ax, 10
>add ax, bx
>iret

This will pop half the return address. The stack parameters are pushed
*before* the return address. You need something like "mov bx, word ptr
[sp+4]" (and is that even valid? You might need to setup BP)

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

I suspect the 4 should be 1, or possibly 2. The DPMI spec is rather
unclear. Unfortunately "word" on intel machines is sometimes used to
refer to a 16-bit quantity. The technically correct value would, I
suppose, be 1.

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

Weird. Are you sure you weren't using the "iret" version of the dpmi
call by mistake?

Davin.

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