Re: [avr-libc-dev] RFC: avr/bits.h

[E. Weddington]

Nicolas Schodet wrote:

> Hello,
>
> About bit manipulations, I had a bad experience last week. On some
> registers, bit manipulation can be tricky:
>
> TWCR &= ~(_BV (TWSTA) | _BV (TWSTO));
>
> The interrupt flag bit is read as 1, and writen at 1, this clear the
> interrupt bit! A warning could be added to the manual.
>  
No, the warning is already included in the datasheet for those items, 
specifically the TWI subsystem.

> Another question about bit manipulation: what is the best way to read 4
> bytes into a double word? 
Use a union. This has been discussed before. See the archives.

> This could also be included in the bit
> manipulation header.
No it shouldn't. It has nothing to do with bit manipulation.

Eric