Re: [avr-gcc-list] 24 bits (u)ints

[Georg-Johann Lay]

On 30.11.2016 15:32, Paul "LeoNerd" Evans wrote:
> On Wed, 30 Nov 2016 18:18:11 +0530
> Senthil Kumar Selvaraj <address@hidden> wrote:
>
> > Diogo Martins Silva writes:
> >
> > > Hello all.
> > >
> > > The avr-gcc wiki (https://gcc.gnu.org/wiki/avr-gcc) lists 24 bits
> > > (u)ints as an extension since version 4.7. How do I use them?
> >
> > Use __uint24 as the type. Like so
> >
> > $ cat test.c
> > volatile __uint24 x;
> > int main() {
> >   x++;
> >   x--;
> > }
>
> Is it possible to get that added to <stdint.h> as the expected names
>
>   int24_t
>   uint24_t
>
> ?

The C99 and later standards don't supply these types or reserve these 
identifiers.  Since C99, "int8_t" is an identifier that resides in the 
namespace of the implementation, whereas "int24_t" is still in the 
namespace of the application.  Hence, for the new 3-byte types names 
were chosen that are in the namespace of the implementation, i.e. 
reserved identifiers which start with "__" (__int24 and __uint24).

If you like you can define such types in your application, but they 
should not go into any standard header.

Johann