Re: [avr-gcc-list] Someting I don"t understand with PGM_P et pgm_read_byte_far()

[Bernard Fouché]

E. Weddington a écrit :

> Bernard Fouché wrote:
>
> > So it appears that, even for an ATMEGA128, a PGM_P data type is a 16 
> > bits pointer. 
>
>
> That is correct.

IMHO PGM_P and PROGMEM should adapt to the flash space size of the 
target. I'm writing code that has to work for atmega64 & 128, and I have 
to redefine my own set of macros to have such a fonctionnality (I don't 
like to patch 'system' file like pgmspace.h). I don't see yet how to do 
so for PROGMEM since it is just a rewrite of __attribute__((__progmem__)).

For instance, how not to have a compiler warning for:

uint8_t Xy[3] PROGMEM = { 1,2,3 } ;

uint8_t f(uint32_t x)
{
   return pgm_read_byte_far(Xy+x);
}

when compiling for atmega128 ??

Is there a chance that sometimes such macros will change of data type 
according to the target in a future release?