RE: [avr-libc-dev] 64-bit doubles

[Ron Kreymborg]

> > -----Original Message-----
> > From:
> > address@hidden
> > [mailto:address@hidden
> > org] On Behalf Of Dave N6NZ
> > Sent: Saturday, December 20, 2008 5:39 PM
> > Cc: address@hidden
> > Subject: Re: [avr-libc-dev] 64-bit doubles
> >
> > Is support for 64 bit double limited only by availability of a math
> > library?  I would expect that 8-byte variables, register allocations,
> > etc, would also be an issue, since avr-gcc doesn't have
> > anything bigger
> > than a 32-bit long or 32-bit float right now.
> >
> > Isn't there some compiler infrastructure that would have to
> > happen also?
> 
> Yes, we need to have both the library support, as well as the compiler
> support. The compiler work might be easier than the library work, but
> this is just conjecture.
> 
> Eric

For the moment I am thinking of implementing fp doubles as the typedef
"longfp" in long longs. As Preston has mentioned, this would be outside the
compiler. They would have the IEEE format, ie 52-bit mantissa and 11-bit
exponent. Obviously not the most efficient but very testable.

Ron






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