Re: [avr-gcc-list] SBI an CBI optimizations

[Alex Wenger]

Hello,

Trampas schrieb:
> I am using WinAvr GCC 3.4.3 so this may have been fixed in 4.0, but I have
> noticed that the compiler does not optimize the following:
>
>
> #define DISABLE_INTO_ISR() {GIMSK=GIMSK & ~(1<<INT0);}
>
> 176:rs485.c       ****  DISABLE_INTO_ISR();
>  247                    .LM24:
>  248 0086 8BB7                  in r24,91-0x20
>  249 0088 8F7B                  andi r24,lo8(-65)
>  250 008a 8BBF                  out 91-0x20,r24
>
> That is unless I am mistaken this can be done with a CBI instruction? 

no, when you write: GIMSK=GIMSK & ~(1<<INT0);
you mean read, modify, write.
you should write GIMSK &= ~(1<<INT0);
then it should work.

/Blueloop