Re: [Contiki-developers] printing floating point numbers

[Carlo A. B. <cb...@si...>]

Hello Nahuel,
I was able to print floating numbers on the Tmote Sky. Here is how I did it:

#include <math.h>

int a1=7, a2=8;
float b1 = (float) a1*1.000;
float b2 = (float) a2*1.000;
float f = b1 / b2;
printf("%d / %d = %ld.%03u\n", a1, a2, (long)f, 
(unsigned)((f-floor(f))*1000));

You also need to hack on your makefile to enable the compilation of the 
math library. My solution is as follows:
CUSTOM_RULE_LINK=1
%.$(TARGET): %.co $(PROJECT_OBJECTFILES) $(PROJECT_LIBRARIES) 
contiki-$(TARGET).a
     $(LD) $(LDFLAGS) $(TARGET_STARTFILES) ${filter-out %.a,$^} ${filter 
%.a,$^} $(TARGET_LIBFILES) -o $@ -lm

Best Regards,
Carlo




Il 10/08/2010 17:19, Marek Bykowski ha scritto:
> Hello,
>
> There is no Floating Point Unit on the most of embedded platforms.
> The compiler version under Contiki doesn't support float formats.
>
> Grep through Contiki directories - there is almost no float 
> definitions in the files. Try to avoid it as much as possible. Use 
> fixed point arithmetic if needed.
>
> Cheers,
> Marek
>
> On 10 August 2010 15:11, Nahuel Marisi <nah...@gm... 
> <mailto:nah...@gm...>> wrote:
>
>     I'm having a simple, yet weird problem.
>
>     Every time I try to print floating point numbers using the format
>     specifier %f I get an f literally printed.
>
>     for example,
>
>     printf("floating point number: %f\n",131.231);
>
>     prints: floating pointer number f
>
>     Basically I'm using the energest module and use %li to print its
>     values, but when I try to convert it to energy use (dividing by
>     8192 and
>     multiplying by 3 and 20 ) if I printed using long ints I just see
>     0. The difference prints fine
>
>
>
>     any ideas?
>
>     Thanks,
>     Nahuel
>     ------------------------------------------------------------------------------
>     This SF.net email is sponsored by
>
>     Make an app they can't live without
>     Enter the BlackBerry Developer Challenge
>     http://p.sf.net/sfu/RIM-dev2dev
>     _______________________________________________
>     Contiki-developers mailing list
>     Con...@li...
>     <mailto:Con...@li...>
>     https://lists.sourceforge.net/lists/listinfo/contiki-developers
>
>
>
> ------------------------------------------------------------------------------
> This SF.net email is sponsored by
>
> Make an app they can't live without
> Enter the BlackBerry Developer Challenge
> http://p.sf.net/sfu/RIM-dev2dev
>
>
> _______________________________________________
> Contiki-developers mailing list
> Con...@li...
> https://lists.sourceforge.net/lists/listinfo/contiki-developers
>