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Re: fr30 FP format question




Toon Moene wrote:
> 
> Joel Sherrill wrote:
> 
> > FR30 can't build fortran because this is being tripped
> > in gcc/f/target.h:
> >
> > /* For now, g77 requires the ability to determine the exact bit pattern
> >    of a float on the target machine.  (Hopefully this will be changed
> >    soon).  Make sure we can do this.  */
> >
> > #if !defined (REAL_ARITHMETIC) \
> >   && ((TARGET_FLOAT_FORMAT != HOST_FLOAT_FORMAT) \
> >       || (FLOAT_WORDS_BIG_ENDIAN != HOST_FLOAT_WORDS_BIG_ENDIAN))
> > #error "g77 requires ability to access exact FP representation of target
> > machine
> > "
> > #endif
> >
> > The fr30 appears to only have software floating point based upon
> > fr30/t-fr30 so I was thinking this had to be easy to fix but
> > don't know precisely what I am looking for to compare against. :(
> >
> > Could someone point me in the right direction?  Thanks.
> 
> As far as I can see, the only comparison in the above conditional that's
> not true is FLOAT_WORDS_BIG_ENDIAN != HOST_FLOAT_WORDS_BIG_ENDIAN.
> 
> This is so, because the fr30 is a big-endian machine (which means that
> its FLOATs will be big-endian also, by default), whereas the ix86, from
> which you want to cross-compile, is a little-endian machine, with
> little-endian FLOATs.
> 
> This means that you should be able to build the cross-compiler on a
> big-endian machine, like powerpc, sparc, mips or s390 ...

But I can build this library for any number of other CPUs.  I can
do x86 to arm, powerpc, mips, sparc, etc.  I think most of those 
are big endian by default.  

> --
> Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
> Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
> Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html
> Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction)

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel@OARcorp.com                 On-Line Applications Research
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