From: Tristan Wibberley <bloater@ps.cus.umist.ac.uk>
  To  : ggi-develop@eskimo.com
  Date: Fri, 13 Aug 1999 16:33:48 +0100

Re: GGI and XFree86 and stuff

On Fri, Aug 13, 1999 at 11:11:13AM +0200, becka@rz.uni-duesseldorf.de wrote:
> Hi !
> 
> > > Before we get overly enthusiastic about PingPong and stuff:
> > > The locking problem needs to be solved. If we go for an asynchronous
> 
> > I'm assuming this is for cards that can't have the framebuffer and accel
> > accessed at the same. 
> 
> No. This is for each and every card. Say you want to erase the screen and 
> then draw a diagonal line on it. Assume further, that boxes are accelerated,
> but lines are not.
> 
> Now if you issue the fillscreen command, and it does not get executed 
> immediately, but only at the next buffer flush, you will draw the line 
> first, and lateron, when the buffer is full and gets flushed, you will
> fill the screen. This is obviously wrong, as the net effect is the line 
> not being visible.

Can't you let te programmer decide when he/she needs to wait for the
flush, and give them a function to wait for the flush to complete. This
way, if the programmer knows that the buffered accels will not disturb
his/her fb access, they can do both at the same time? Is this too much
work for too little gain?

-- 
Tristan Wibberley