Re: [avr-gcc-list] interrupt optimization

[Lars Noschinski]

* Paulo Marques <address@hidden> [2006-02-02 23:55]:
> Then, to call the function, just do in assembly:
>         in __tmp_reg__, SREG
>         push __tmp_reg__
>         call _not_inline_function_
>
> The __tmp_reg__ (SREG) push is made to match the IRET instruction from the now 
> "interrupt" function.

If the function call is the last thing you need to do, you can also
replace the call by a jmp instruction (of course, you may not push
something to the stack).

For example, i've an interrupt which only does something, if there is
an bit in an IO register set:

#define NAKED __attribute__ ((naked))

NAKED SIGNAL (SIG_INTERRUPT1) {
   if (_BV(PB0) & PINB)
       return;
   asm ("rjmp do_work" "\n\t");
}

This ensures minimal overhead, if this condition is not met.