Hi everyone,
I'm trying to improve the performance of some code I have, and it occurred to me maybe I'm not making efficient use of the cache.
However, then it occurred to me that I don't know for sure whether the Dragonball 68k processors even *have* a cache. I looked at some of the documents on Motorola's (well, Freescale's) site, and found no information either way. I don't recall that the original 68000 chips had a cache, but I'm not sure how much of a redesign the Dragonball chips are, so for all I know they added a cache.
The Dragonball 68K CPUs have no cache. They were basic low-power 68K cores with a lot of embedded peripherals.
While I'm asking questions, I assume the ARM processors do have a cache. Is that right? Oh, and one more: can I use floating point in ARM code? (I.e. are ARM-based Palms required to have floating point ARM instructions?)
Palm OS does not require that the ARM CPUs used for the OS have an FPU unit. Most do not. That's why the choice of compiler is important, as the quality of the software floating point implementation matters a lot. Palm OS does FPU emulation, intercepting the "illegal instruction" trap, but that's a very slow route. I know CodeWarrior for Palm OS has a pretty good FP library for ARM code. Current versions of PRC-Tools for Palm OS still use the FPU emulation in the OS, AFAIK, but the GCC people are working on a good software FP implementation.
-- Ben Combee, Technical Lead, Developer Services, PalmSource, Inc. "Combee on Palm OS" weblog: http://palmos.combee.net/ Developer Forum Archives: http://news.palmos.com/read/all_forums/
-- For information on using the Palm Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/
