Re: [avr-gcc-list] interrupt in as

[Kang Tin LAI]

Hi, 

Try these:

void SIG_INTERRUPT0(void) __attribute__ ((naked));
void SIG_INTERRUPT0(void)
{
        /* your codes */
}

No overhead, including "reti", even not in pure assembler code.

Kang

Torsten Hahn wrote:
> 
> Hi,
> 
> can explain me somebody how can i implement an interrupt-handler purely in
> assembler ?
> 
> I would need an interrupt routine with no overhead from the c-compiler. If I
> use
> 
> SIGNAL(INTERRUPT0)
> {
> asm("nop");
> }
> 
> I get code output like this:
> 
> 000000b4 <_interrupt1_>:
>   b4:   1f 92           push    r1
>   b6:   0f 92           push    r0
>   b8:   0f b6           in      r0, 0x3f        ; 63
>   ba:   0f 92           push    r0
>   bc:   11 24           eor     r1, r1
>   be:   00 00           nop
>   c0:   0f 90           pop     r0
>   c2:   0f be           out     0x3f, r0        ; 63
>   c4:   0f 90           pop     r0
>   c6:   1f 90           pop     r1
>   c8:   18 95           reti
> 
> The Problem is now, that i have an extremly time critical applikation and i
> have for some reasons only 16 (!) takt-cycles to handle this interrupt
> optimal. The code constructet wasts about 12 of them.
> 
> Thanks,
> TH.
> --
> Torsten Hahn / Chemnitzer Str. 4 / 09599 Freiberg / Germany
> mail: address@hidden
> phone: (+49) 177 2181338
> pgp key avaiable at: http://math-www.uni-paderborn.de/pgpnet/wwwkeys.html
> 
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