[avr-gcc-list] Re: __DATE__ constant, any way to format it differently ?

[David Brown]

Heike C. Zimmerer wrote:
> "Anton James Erasmus" <address@hidden> writes:
>
> > You can use the following MACROS and functions to get the
> > values in integer format. You can then display the date and
> > time in whatever format you desire.
> >
> > #define COMPILE_HOUR (((__TIME__[0]-'0')*10) +
> > (__TIME__[1]-'0'))
> > #define COMPILE_MINUTE (((__TIME__[3]-'0')*10) +
> > (__TIME__[4]-'0'))
> > #define COMPILE_SECOND (((__TIME__[6]-'0')*10) +
> > (__TIME__[7]-'0'))
>
> is __TIME__ guaranteed not to change between invocations?  Else you may
> end up at 1:00:00 where 1:59:59 would have been appropriate.
>
>
> > unsigned char GetCompileHour(void)
> > {
> >   unsigned char hour=COMPILE_HOUR;
> >   return(hour);
> > }
> > [...]
>
> This all happens in the AVR where space is tight.  I prefer a small
> shell script which prepares a .h file containing all constants (date,
> build #, hardware revision, etc) in their final representation.

Note that if you declare these functions "static inline", they will 
avoid the function call overhead and some space - the compiler will 
reduce them to a single "ldi" instruction.  It's still not quite as 
compact as a compiled string, but it's an improvement.