This reduces the number of Screen_fault_handler() calls by 80%. i.e. VOSF
is now viable on this turtle MacOS X. Besides, since there is no buffer
comparison, idle sleep can really be effective. SheepShaver in idle mode
on my PBG4 now goes below 8% of CPU resources instead of 70-80% with
bounding boxes based video refreshes.
Caveat: if your program doesn't use standard MacOS routines that call NQD,
then you can expect slower (visual) performance. However, I do think the
new default behavior (VOSF+NQD) is the most common.
This does not improve graphics performance but helps CPU because it reduces
the number of bytes transfered to actual screen. I saw an improvement by up
to 26% in frameskip 4 800x600x16 but also a hit by 3% with frameskip 0.
The next step is to use NQD bounding boxes to help detecting dirty areas.
So far, this is the best I can do without VOSF working (MacOS X performance
bugs -- pitifully slow Mach syscalls)
- Properly handle migration from "screenmodes" and "windowmodes" to "screen"
- Fix has_mode() logic to really test for actual mode availability. i.e.
no longer start in large screen mode if user specified a max size.
interrupt in one_tick() if no pthreads at all are used, i.e. ether_dummy
is effective in that case. Otherwise, don't trigger ethernet again if
pthreads are available (and ether_unix) and cpu emul services are active.
can have a chance in case VOSF is not profitable (on video mode switches)
Improve video mode switches in SheepShaver/SDL, aka avoid crashes on win32
as there is apparently no thread canceleation algorithm used in SDL/win32.
