I'm a little confused by your comments. I'd expect a custom optimized
blitter you wrote for a 68K based Palm device to be slower than the OS
blitter in Palm OS 5 because the former will be emulated while the latter
will be ARM native. What was once faster is now slower. The reason the
emulator is indeed fast is that most of the time an application is running
it's in an OS routine. All the OS routines are now ARM native, so they run
nice and fast.

If you've got a processing bottleneck in your application (such as computing
values in the Mandelbrot Set, as John Marshall did), these will have enough
work to do that even when running ARM native, they'll still swamp the
overhead of getting to and from ARM native code. If instead you have
something that gets run a huge number of times, and is a bottleneck only
because of that, then porting it to ARM won't help you. You need to get that
inner loop into ARM native code!

Don't trust your intuition when it comes to optimizing code. Run a profiler
such as the one provided in POSE, and examine the results carefully. When
you do find a bottleneck and optimize it, another bottleneck will be
exposed. You can keep doing this, but after a few iterations you'll tend to
have no one big bottleneck, but rather a bunch of separate things that each
take 20% of the time. That's a good time to stop ;-)
-- 
Peter Epstein

-- 
For information on using the Palm Developer Forums, or to unsubscribe, please see 
http://www.palmos.com/dev/tech/support/forums/

Reply via email to