/dev/video ?

[Konrad Kokoszkiewicz <draco@mi.com.pl>]

Hi,

we have /dev/audio, what about a sort of a /dev/video (or whatever name
for it)?

I mean, it is rather well known fact, that there are permanent problems
with customized video modes on Falcon (for example). Also the standard
XBIOS call doesn't seem to work as expected ( = as described in Falcon
developer documentation). Basically, for example, the Vsetscreen() doesn't
reallocate the screen memory properly, especially if a video expander
(BlowUp, Videlity, Videl Inside, Screen Blaster) is installed.

Due to that people are using hardware directly, what works, but needs a
switch to supervisor and may cause problems with memory protection.

Thus the idea of making a video hardware driver like the /dev/audio serves
for the audio hardware. It could do such things as:

- allocating separate screens in the ST RAM without messing up the
  area assigned to the VDI output (f.e. we are playing a game which 
  uses the screen directly in customized video mode, and by this time we
  have normal desktop underneath - no need to lock the screen against
  writes from other programs etc., GEM applications can still run in
  the background on multitasking systems).
- reading video hardware registers to a buffer
- writing video hardware registers from a buffer
- reading/writing palette registers (like Vget/setRGB() does)
- switching to predefined video modes on an unified way.

This could also include emulation for a hardware, that we don't have
(e.g. the device could optionally emulate proper ST/TT/Falcon video
hardware behaviour on gfx cards, i know that it may be hard).

I think such a device, if well planned, may facilitate writing games,
demos and other programs those need to access the screen directly, and
designing them to run in multitasking. So, sort of DirectX.

What do you think? 

--
Konrad M.Kokoszkiewicz
|mail: draco@mi.com.pl                  | Atari Falcon030/TT030/65XE |
|http://www.orient.uw.edu.pl/~conradus/ | ** FreeMiNT development ** |

** Ea natura multitudinis est,
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