API modification request

[Ralf Corsepius]

Am Die, 2003-02-04 um 00.35 schrieb Joel Sherrill:
> Till Straumann wrote:
> > 

> > 3) Ralf: passing an ISR arg is not supported in hardware on all
> >           CPUs (e.g. SH1), additional lookup needed.
> 
> This is OK I think because even the code in sh7032/cpu_asm.c has
> to figure out the vector number to invoke the handler. 
Yes, but ..

>  So it is
> only 1 logical step away from being able to index into a table 
> of pointers.
This is probably true on the caller-side, but I am not sure about the
impact on the callee-side, if looking up an IRQ argument from inside the
ISR is required. I suspect this penalty to be handful of instructions
and to be several dozens of wait-states. Memory consumption for lookup
tables might also be a concern (1-wait-state memory is scarce on the
SH1s: Only 2k)

Ralf