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Mail Archives: djgpp/2000/06/06/16:00:14

From: Joseph Morris <jpm AT it-he DOT org>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: svga
Date: Tue, 06 Jun 2000 20:52:24 +0100
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Martell wrote:
> 
....
> I would like to write the graphical functions myself, just for the knowledge of
> how they work, so using pre-written functions is not what im looking for here.

Ok then.  Have you considered using FAR pointers instead?
The technique I used in my ITG library before I switched to Allegro was to use a
307K back-buffer and blit this to the screen with a suitable 'driver' written
in ASM.  I was also able to use an SDL 'driver' to do the blit work in Linux,
Windows and BeOS. (But it got tangled eventually, hence Allegro)

I allocated a segment to point to the video display using C.w. Sandmann's SVGA
examples, and then used rep movsd to copy the back-buffer to the screen.

I had a banked driver that copied this in 64k chunks, but I had ot be careful to
set the destination pointer back to 0 each time.  You are doing this, yes?

If you're interested, the source code for the ITG drivers is in the IRE project,
at http://fly.to/ire where you can download the source and have a look.
The next release will use Allegro.

> 
> -Jeremiah

-- 
JP Morris - aka DOUG the Eagle (Dragon) -=UDIC=-  doug AT it-he DOT org
Fun things to do with the Ultima games            (http://www.it-he.org)
Developing a U6/U7 clone                          (http://fly.to/ire)
d+++ e+ N+ T++ Om U1234!56!7'!S'!8!9!KA u++ uC+++ uF+++ uG---- uLB----
uA--- nC+ nR---- nH+++ nP++ nI nPT nS nT wM- wC- y a(YEAR - 1976)

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