Re: [avr-gcc-list] Code version timestamp

[John Altstadt]

address@hidden wrote:
> Dear All,
>
> I would like to display a "code version" (date/time or incremental number)
> during init on an LCD display.
> Does anybody know if there is any information in the executable (ROM file) that
> I can use at runtime (updated by the linker for example) ?
>
> If no, does anybody know how to implement this ?
> I was thinking to generate an asm code using a script in the make, but seems to
> be complicated.
>
> Thanks for your suggestions.
> Eric.

Look at the __DATE__ and __TIME__ predefined macros. Since they are 
already string constants, you can use the compiler to concatenate them 
with the string you want to display, such as:

char *version =
"Compiled on " __DATE__ " at " __TIME__;

Put this line by itself in a file called version.c, and then change the 
appropriate Makefile target to remove version.o as the last step, e.g.:

%.elf: $(OBJ)
        @echo
        @echo $(MSG_LINKING) $@
        $(CC) $(ALL_CFLAGS) $^ --output $@ $(LDFLAGS)
        rm version.o

This way, every time you build the target, version.c will be compiled, 
giving you a new version string corresponding to the time you built the 
project. Make sure that version.c is the last file compiled by putting 
it last in the source file list in the Makefile.

There are other predefined macros that may prove helpful for 
identification and debugging. I sometimes use __FILE__ and __LINE__ for 
debug and error messages. Check out section 3.7 Predefined Macros in the 
cpp docs.

To get a list of some of the predefined macros (not all of them, unlike 
what it says in the cpp man page), run the command:

touch foo.h; avr-cpp -dM foo.h

assuming that foo.h doesn't exist before you start.

John