Re: GCC for embedded PowerPC systems

[Michael Rausch <marausch at inwind dot it>]

On Mon, 27 Sep 2004 20:20:37 -0700 (PDT), Muthukumar Ratty 
<muthu@iqmail.net> wrote:

> > 1) - Why is the #interrupt directive ignored by the PowerPC version of 
> > GCC?
>
> What does it do?
Ooops!
The direcive is of course "#pragma interrupt".
I expected it to instruct the compiler to generate a "return from 
interrupt" instruction at the end of the routine, instead of a "return    
from subroutine".
This is what happens for the SH2.
The PowerPC actually has a "rfi" instruction, but the compiler silently 
ignores the directive; the generated assembly code is the same and there 
is no "rfi" at the end of the routine.

> > 2) - Is it possible to write an interrupt service routine in pure C
> > language?
>
> Yes.
Without embedded assembly?

> > 3) - Is there any prologue/epilogue code to be written for interrupt
> > service routines?
>
> No. Just the regular stuff, no blocking, quick, nested intr handling etc.
You mean that prologue/epilogue are the same for interrupt services 
routines and normal functions?

> Google?
I took the decision to ask the mailing list after about one month of 
"googling" without finding really satisfying information (maybe there are 
better keywords than: GCC, GNU, EABI, interrupt, Powerpc, and so on... ;-) 
).

Thank you for your help!
--
Mch