Re: [avr-libc-dev] [bugs #12040] sbi in FAQ

[Erik Walthinsen]

David Brown wrote:
> The first case here asks the compiler to set two bits
> high at the same time, and it does that - something that cannot be expressed
> with sbi/cbi.  The second case asks the compiler to set the bits one after
> the other, and again it provides optimal correct code.  I can't see how the
> compiler could produce anything better.

Yes, you're right.  Sorry, I was trying to make a point in frustration 
and latched onto a bad example.

I'm currently drafting avr/bits.h mostly as per E. Weddington's initial 
spec, and an RFC explaining it.  I'm putting a significant amount of 
information in the documentation regarding the use of various 
bit-twiddling method and their various side effects, such as those 
mentioned above.  I hope to get it posted tonight, but it's already past 
midnight, we'll see.