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

[Russell Shaw]

Albert Seward wrote:
> On Thu, 2 Dec 2004, E. Weddington wrote:
>
>
> > Albert Seward wrote:
> >
> >
> > > I have some problems with code generation from GCC 3.3. Read my question
> > > in the main block.
> > >
> > > /*
> > > * bitfields.c
> > > *
> > > * GCC bitfields optimization test
> > > */

...

> > > Hope anyone has the time to help me. I am really stuck.
> > 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
> >
> > See this thread on the AVR Freaks website on how to use these operators:
> > <http://www.avrfreaks.net/phpBB2/viewtopic.php?t=8764&highlight=programming+101>
> > Go to the post that starts with "Programming 101", which should be
> > highlighted.
>
> If I wanted to do it the "canonical way" would I have ask for it. But I
> didn't, did I?
>
> I do wonder how your brain work. I wish I would have taken a degree in
> philosophy instead of my master degree in computer science.
>
> But hey, thanks for the link. Here is a link so you can learn some
> "Reading 101"
> http://www.fisher-price.com/us/ms5/learn-to-read.asp
>
> Enjoy.

#define SETB(REG,POS)   REG|=_BV(POS)
#define CLRB(REG,POS)   REG&=(~_BV(POS))

eg: SETB(UCSRB,TXEN);