From: teunis <teunis@computersupportcentre.com>
  To  : ggi-develop@eskimo.com
  Date: Mon, 21 Sep 1998 01:23:41 -0700 (MST)

Re: Events and Joysticks

On Mon, 21 Sep 1998, Andrew Apted wrote:

> Hi all,
> 
> At the IRC meeting Andy and me discussed what joystick events should
> look like.  We didn't get very far though... so here is a concrete
> proposal for further discussion and (hopefully) implementation.

[clip]

As someone who's going to use it and used EvStacks while I could, I like
it :)
[and don't see any probs with this]

BTW folks : XFree86 has a joystick extension...  Not sure how it works
other than it exists.
Under X (And other window/device-managing systems),
	X -> events / filter -> GGI events
	grab device -> filter -> -^ (if and only if needed)

Under other systems:
	grab device -> filter ->  \
	grab device -> filter ->   >-> GGI events
	grab device -> filter ->  /

Under GGI subtargets:  (must activate this! default is previous model!)
	[source pipe? SHM?] -> filter -> GGI events
	        grab device -> filter -> -^  (also only if needed)

My vote goes with SHM btw...  Makes it more like EvStacks although a lock
(ie: semaphore) should be used to lock the event filter as needed...
The pipe method -may- look easier but the SHM method is far more
efficient... Particularily if you've got large numbers of events going
through and want to minimize copying.  Just lock it when you start sending
events and unlock once the events have been cleared (blocks of I/O).
for single events it's not quite as efficient due to the transfer into
kernelspace for the semaphore - but that's not serious IMHO.

G'day, eh? :)
	- Teunis