On Tue, 2005-02-15 at 11:47 +0000, Dave Airlie wrote: > > > > > > I'm thinking about how these could be used in Mesa drivers? would I be > > > correct in thinking the fallbacks would mess up as the Mesa copy of the > > > texture wouldn't be the same as what the card would be using? > > > > I'm not sure that the fallbacks in their current form ever actually read > > from > > the on-card texture memory. > > No the onboard memory or GART copy would be the same as the copy Mesa > keeps, the only difference would be the bit in the register would mean the > chip would auto-swizzle when it is reading the texture... so if I have > > an RGBA 8888 and set the bit the radeon will treat it like a ABGR 8888 but > not actually change any copies of it.. so in terms of operations on the > texture the fallback would work on a RGBA, the chip operations on ABGR
Note that at least for this example, you don't need the endianness bits at all, as you can just choose the RGBA vs. ABGR hardware formats. It might also be possible to fix up the byte order during the upload blit, but I guess you may be trying to get rid of that for the GART... Way back when I was fixing the r128 driver for PPC, I bumped into problems like alignment issues with higher mipmap levels when I tried to use the texture endianness bits, in particular with 16 bit textures. That's why I figured it was easiest to always have Mesa provide texture data in little endian. I don't know if those issues still apply to your scenario or even in general though. -- Earthling Michel DÃnzer | Debian (powerpc), X and DRI developer Libre software enthusiast | http://svcs.affero.net/rm.php?r=daenzer ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
