Mail Archives: djgpp/1998/03/30/19:09:18
I have uploaded a preliminary version of the FreeBE/AF graphics driver
project to http:/www.talula.demon.co.uk/freebe/.
What is FreeBE/AF?
------------------
FreeBE/AF is an attempt to implement free VBE/AF drivers on as many
cards as possible. This idea came about on the Allegro mailing list,
due to the need for a dynamically loadable driver structure that
could support hardware acceleration. VBE/AF seemed to fit the bill,
and Allegro already had support for the SciTech drivers, so it seemed
like a good idea to adopt this format for ourselves. The primary goal
is to make these drivers work with Allegro, so the emphasis will be
on implementing the functions that Allegro actually uses, but we will
do our best to keep things in line with the official spec so that the
results may be used with any future VBE/AF applications as well.
What is VBE/AF?
---------------
VBE/AF is a low level driver interface for accessing graphics
hardware. It provides all the same features as VESA, and adds the
ability to use 2D hardware acceleration in a portable manner. An /AF
driver is provided as a disk file (vbeaf.drv), and contains clean 32
bit machine code which can (with a few exceptions) be called directly
by a C program. If implemented correctly, these drivers have the
potential to be binary portable across multiple operating systems, so
the same driver file can be used from DOS, Windows, Linux, etc.
What can I do with this?
------------------------
Currently not very much! There is only one driver: the stub. This is
not useful in any way, because it simply sits on top of your existing
VESA driver and emulates a few "hardware" drawing operations with
very slow software implementations. The stub is intended as a
starting point for people who want to make drivers for a specific
card: we need your help to support lots of different chipsets...
Of course, you will also need a VBE/AF application to use with the
driver. This stub implementation has been tested with the SciTech
VBETEST program and the work-in-progress version of Allegro
(http://www.talula.demon.co.uk/allegro/wip.html), and it works
correctly with both. You will need the WIP patch to use it with
Allegro, because VBE/AF support was not fully enabled in Allegro 3.0.
Credits
-------
The DRVGEN utility is based on the djgpp DXEGEN system, by Charles
Sandmann and DJ Delorie.
Linking and relocation system by Ove Kaaven.
VBE/AF driver framework by Shawn Hargreaves.
Hardware specific chipset support by <insert your name here> :-)
--
Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
"Pigs use it for a tambourine" - Frank Zappa
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