From: Richard Nichols <tiberius AT mailhost DOT net>
Newsgroups: comp.os.msdos.djgpp
Subject: Getting to the bottom of this
Date: Sat, 10 Jan 1998 12:03:04 +1000
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Hmm..  after my numerous posts on bugs and stuff I've decided that
it must be NASM that's screwing my library (or my use of NASM).
My library is a hulking beast like allegro (only about 45% of that
functionality yet though) which is making debugging difficult. I
would wager that I have numberous bugs which are causing weird errors.

Here is the way I am using nasm:

-I only preserve ds when I use it. I often clobber es and all offset
 regs
-I store ebp and mov ebp, esp to reference the function's args if
I've messed around on the stack I mov esp, ebp at the end before
popping ebp
-does using ebp with debug info on cause any worries?
-I have MIDAS sound system running in the background. Is this a
problem?

Here is a sample procedure to write to the LFB. I've gotten myself
a selector to the LFB. I know this function causes problems so
what's wrong???

;
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
; gfxSendToLFB : Sends the data pointed to to the lfb
;
; void gfxSendToLFB(UCHAR *data, int length);
;
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
;_gfxSendToLFB:
;        push ebp
;        mov ebp, esp

;        push dword [_vidLFB_Seg]        ; es = LFB segment
;        pop es                          ;
;        cld                             ;
;        xor edi, edi                    ; edi = 0
;        mov esi, [ebp +  8]             ; esi = data
;        mov edx, [ebp + 12]             ; edx = count
;        mov ecx, edx                    ; ecx = count/4
;        shr ecx, 2                      ;
;        rep movsd                       ; copy data
;        mov ecx, edx                    ; ecx = count mod 4
;        and ecx, 3                      ;
;        rep movsb                       ; copy left over data
;
;        mov esp, ebp
;        pop ebp
;        ret

And another thing, I'm using NASM 0.97 and when I do [SECTION .text
ALIGN=4]
I get an error: standard coff format does not support section alignment
the examples from djppasm.doc all have this error. Has something changed
in a subsequent version of NASM?

hmm.. I know I've got a lot of problems there but I'm really starting to
get
annoyed with this...

-Rich

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  | Richard Nichols              | Inspire Media (Demos/Games)    |
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