Re: [AD] DGA acceleration

[George Foot <gfoot@xxxxxxxxxx>]

On Tue, Sep 19, 2000 at 06:10:27PM +0200, Angelo Mottola wrote:
> Ok, I've sat down and investigated a bit on the topic. I've also studied your
> (Bukin) xwin.c code, and I've finally managed to add some sort of initial hw
> acceleration support.

Hi Angelo,

I suggest you post the code you're using, or patches if they're
appropriate -- I know very little about X, and nothing about
acceleration in X, but more pairs of eyes may help find the
problem.

Generally, I'd suggest doing initial tests in really simple programs,
without the complication of the test program, and just using the
test program for profiling later on.

We need to find out why the offsets are 8 and 30 pixels; maybe
it's the distance of your window from the top left of the
screen, or the offset due to the window border?  Maybe it would
be useful to just try the function using window coordinates
directly, ignoring what Allegro asks for, to see how the
functions work first.

For documentation on XF86-specific routines, I'd suggest looking
around the XFree86 website -- they ought to be there somewhere.

> mode? And another thing: I know XF 3.3.x is still widely used, so the current
> Allegro DGA driver should remain untouched. The new driver I'd like to code
> would need Allegro to autodetect in the "configure" step which driver to
> compile: the one for DGA 1.x or the other for DGA 2.0... Modifying the current
> DGA driver to detect which DGA version is in use at runtime is possible, and it
> would cut off the need of writing a separated driver, but DGA 1.x and 2.0 APIs
> are different AFAIK - and I'm beginning to doubt they're really compatible - so
> I don't know if this is worth the effort after all.
> Now I need more comments and suggestions!

I think it could be OK to only compile for the DGA version this
system is running, generally, but maybe somebody's system has
two versions of X around.  I think it would be bad to require X
to be running at the time of running the configure script -- the
most you can do is check what the DGA library and headers
installed support.  If they support both, compile both drivers,
and decide which to use at runtime, preferring the DGA 2.0 one.

George

-- 
Random project update:
09/05/2000: Libnet 0.10.8 uploaded -- a few bugfixes
        http://www.canvaslink.com/libnet/  (try changes-0.10.8.txt)