Re: [avr-gcc-list] Efficient I/O handling w. bitfields codegen problem

[E. Weddington]

Ned Konz wrote:

> On Thursday 02 December 2004 3:00 pm, E. Weddington wrote:
>  
>
> > The canonical way to change bits in ports in C language is not through
> > the use of bitfields. You need to learn to use the C language's bitwise
> > operators, in conjunction with a simple macro include in avr-libc:
> >
> > #include <avr/io.h>
> > PORTA |= _BV(1);   // Set bit 1
> > PORTA &= ~_BV(1);    // Clear bit 1
> >    
>
> Actually, GCC does a nice job (when the optimizer is on) of using bitfields. 
>
>  
The OP didn't specify his command line, so it's indeterminate if the 
optimizer was on.

> It just looks like it's producing inefficient code to access const fields in 
> const structs.
>
>  

I'm sure he could look at the gcc source code to find out.