Re: [avr-gcc-list] Program Space String & optimization

[David Kelly]

On Dec 14, 2005, at 8:57 AM, Joerg Wunsch wrote:

> > volatile PGM_P txt= P_Txt;
>
> Your volatile qualifier is at the wrong place.  You're marking the
> object "txt" points to as volatile, not the pointer itself.  Change
> that into
>
> PGM_P volatile txt = P_Txt;
>
> and it will work.

Believe that is correct. But the other thing that was tripping him is  
in general all function calls are effectively volatile as well. Call  
a function and expect it will be called simply because you said to,  
the the optimizer probably won't descend into the function and decide  
it can be skipped. If the function is inlined then all bets are off.

        do{} while( (a=pgm_read_byte(txt)) );  // Wait for null char

While pgm_read_byte(txt) looks like a function call it is totally macro.

I don't believe this is a problem with the compiler at all, it did  
exactly what it was told it could do.

--
David Kelly N4HHE, address@hidden
========================================================================
Whom computers would destroy, they must first drive mad.