Mail Archives: djgpp/1997/03/05/17:25:44
Tony O'Bryan writes:
>Here is the interesting part, though. If I enable an Allegro timer interrupt
>and put a long enough delay between interrupts (80 milliseconds works on my
>machine), then the problem doesn't show itself. My timer interrupt just
This is very possibly just a fluke: if you aren't doing the blit so
often, the chances are than the soundcard interrupt will occur during
your delay code rather than during the blit itself. I'd guess that you
are just obscuring the trouble, rather that truly getting rid of it...
>My first guess is that blit() my disable the timer interrupt long enough to make
>SBLIB miss its timing mark, but a quick grep of the Allegro source doesn't
blit() doesn't do anything nasty like that. The only hardware access it
does is to change the write plane registers in mode-X...
One possible cause for the trouble that occurs to me is that blit()
loads _dos_ds (or some other selector if you are in an LFB mode), into
%es. I would have expected the SB library to restore all the segments in
it's interrupt handler, but if it is failing to do this for some reason,
problems would result.
Apart from that, I'm baffled. I know several people have used Allegro
and SBLIB together without any trouble, so rest assured that it is
possible...
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* Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
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