[OpenBIOS] (no subject)

[Segher Boessenkool]

> The correct thing to do is similar to SPARC in that you create a 100Hz 
> interrupt (possibly using the PPC decrementer?) that should increment a 
> variable representing the number of ms elapsed. All you need to do is 
> then point the new code towards that variable and it will handle 
> get-msecs and milliseconds automatically.
> 
> The interrupt routine is probably do-able in about 20 lines or less of 
> PPC asm but it's beyond my current PPC-fu. It would be a good project 
> for you though, and would probably fix the incorrect timing CIF 
> milliseconds with -M mac99 :)

There is no reason at all to use the decrementer and interrupts, with
all the problems inherent in that; just use the timebase, it's what
it's for.  The decrementer and timebase tick at the same frequency.


Segher