On Wed, Jun 09, 2004 at 11:36:29AM +0200, Denis Oliver Kropp wrote:
> Quoting Ville Syrj�l�:
> > The mach64 texture engine requires a power of two texture pitch. The
> > attached patch tries to solve the problem by allowing drivers to request
> > power of two pitches.
> >
> > It adds three values max_power_of_two_{pixelpitch,bytepitch,height} to
> > CardLimitaions. If the buffer pitch is below these values the
> > surfacemanager will increase the pitch to the next power of two value.
>
> I wouldn't mind having that in CVS, but I would put the log2 routine
> in "lib/direct/util.h" as direct_log2(), but I'm not sure if this kind
> of log2 function is the mathematically correct version. At least it's
> suitable for "the (next) integer power of two after/of the specified value".
Ok, I'll stick it in libdirect.
> > The biggest problem with this solution is that it can waste a lot of
> > memory needlessly. One solution I can think of would involve the driver
> > setting some flag in CheckState() which would signal
> > dfb_surfacemanager_assure_video() to reallocate the buffer with a power of
> > two pitch. But that might increase memory fragmentation.
> >
> > Any thoughts?
>
> It would be quite complicated, but the surface manager could store the buffers
> interleaved, i.e. use "wasted" memory of one buffer to store another buffer.
Yes I had that idea too. Let's leave it as a possible TODO item for now...
--
Ville Syrj�l�
[EMAIL PROTECTED]
http://www.sci.fi/~syrjala/
