Re: Pointers to add doulle-float capabilities for the avr target

[Tobias Frost <tofr at gmx dot de>]

Thanks a lot... 
This is almost the state I was when I left work today. I never thought,
that will be sufficient ;-) 
I'll give feedback on Monday (tomorrow's holiday --> loooong weekend ;-)

Tobi




On Wed, 2008-05-21 at 19:02 +0200, Uros Bizjak wrote:
> Hello!
> 
> > I am currently evaluation the feasiblitiy to add (real) 64-doubles to the capabilities of the avr-gcc. The current state is, that the avr-gcc supports floats and alias them to doubles. However, a prospective project demands the resolution (accordung to their research), and therefore the company needing it might sponsor me to implement the support.
> >
> > However, beside some trivial patches, I am not familiar with gcc hacking. Therefore it is hard for me to estimated how long this will take, but the numbers are cruicial to deside if I get the assignement. 
> >
> > As far as I dugg into the gcc source, there is a soft-float library which is used widely among non-FPU targets. However, I am currently missing the link, how the target has to be configured to be aware of that. As I am currently stuck with that, I'd appreciate any hint, link, documents etc which might point me into the right direction. 
> >
> >   
> 
> Add this code to avr/t-avr:
> 
> --cut here--
> LIB2FUNCS_EXTRA = fp-bit.c dp-bit.c
> 
> dp-bit.c: $(srcdir)/config/fp-bit.c
>     cat $(srcdir)/config/fp-bit.c > dp-bit.c
> 
> fp-bit.c: $(srcdir)/config/fp-bit.c
>     echo '#define FLOAT' > fp-bit.c
>     cat $(srcdir)/config/fp-bit.c >> fp-bit.c
> --cut here--
> 
> then update avr/avr.h with
> 
> #define FLOAT_TYPE_SIZE 32
> #define DOUBLE_TYPE_SIZE 64
> #define LONG_DOUBLE_TYPE_SIZE 64
> 
> If everything works as expected, then you have just added soft-fp 
> support to avr.
> 
> Uros.