From:	"Rylan" <rylan AT intekom DOT co DOT za>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Using Allegro & Assembly language - video descriptor problem
Date:	Sun, 13 Sep 1998 16:46:09 +0200
Organization:	The South African Internet Exchange
Lines:	30
Message-ID:	<6tgm4b$9fg$3@news2.saix.net>
Reply-To:	"Rylan" <rylan AT inbtekom DOT co DOT za>
NNTP-Posting-Host:	pc25-01-p04.saix.net
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hi,

I have a technical question regarding Allegro:

When I have called install_keyboard and install_timer, is there any way to
still use the segment registers such as ES and DS without GPF'ing the
program out? I need to be able to use ES and DS as descriptors to video RAM
using __dpmi_segment_to_descriptor(0xA000) to set them up before using them
in NASM assembly code - however, after installing the Allegro keyboard and
timer handlers the program crashes the moment it reaches the line where I
place the video descriptor in the ES or DS register. Is there anyway around
this? I suppose this has to do with the fact that the timer routines and /
or keyboard routines are constantly running and thus must always have valid
descriptors in them.

How can I still use custom assembly graphics routines that directly access
video RAM with a descriptor in ES while retaining the functionality of
Allegro's keyboard and timer facilities? Is there some other way than
directly using a descriptor to access video RAM? Will it help to disable
memory protection using DJGPP nearptr() or something?

Any reply appreciated!

--
Spawned By Rylan
Is truth beauty or beauty truth?

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