From: Marcus Sundberg <mackan@stacken.kth.se>
  To  : ggi-develop@eskimo.com
  Date: Fri, 23 Apr 1999 10:56:02 +0200

Re: libggi and direct buffers

> > 1) is it possible sync up with the vertical retrace of the pc's monitor?
> 
> Yes. This is in the ggimisc extension which comes with LibGGI as a
> demo-extension.

Be aware that those functions are not supported by many targets, so
make sure things work when they don't too.

> > i know there is function called ggiAddFlags. 
>
> No - SYNC/ASYNC is something completely different. It is related to _when_
> stuff gets _drawn_ on targets that are not directly connected to some
> hardware, but e.g. have to push data through a network connection like X.

Note however that there will exist a GGIFLAG_FLIPONVBLANK which will
make ggiSetDisplayFrame() flip frames on vblank instead of immediately.
This will be supported by the glide target, and should be supported by
the KGI target once drivers for the new KGI are fully operational.

> > 2) allegro also gives transparent access to linear/paged graphic boards.
> > it therefore requires the granularity of a memory page to be mapped into
> > a single segment. however this value semms to be missing in ggi's direct
> > buffer struct. or is ggi_pixelplanarbuffer.next_page equal to such a
> > value? can you give me a deeper look of what paged buffers in ggi mean?
>
> GGI - on it's preferred targets - avoids paged modes altogether. KGI used to
> linearize paged framebuffers in kernel using the MMU. You would always get
> a linear buffer, even if the card itself is paged.
> 
> Hmm - SVGAlib might have such paged buffers exported. Marcus - any comments ?

The SVGAlib target transparently handles drawing functions in all
cases. On ModeX and paged modes no DirectBuffer is exported.
It wouldn't be too hard to add a paged buffer type and ggiSetPage()
and ggiGetPage() functions. Would be useful for the DGA target too,
which doesn't support paged modes at all yet.

//Marcus
-- 
-------------------------------+------------------------------------
        Marcus Sundberg        | http://www.stacken.kth.se/~mackan/
 Royal Institute of Technology |       Phone: +46 707 295404
       Stockholm, Sweden       |   E-Mail: mackan@stacken.kth.se