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

[Dave N6NZ]

Ron Kreymborg wrote:
> > > 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. 

Well, I learned something.  I've never wanted long long's in my AVR 
code, so I never went looking for them :)  So now I know they are there.

> 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.

Testable? Well.... yes and no :)

Yes, in that since you are choosing the IEEE format many machines will 
give you most of the expected results that you need, modulo a small 
amount of errata.

No, in that the test space is enormous.  Even if you can get expected 
results easily, it still takes a lot of careful test design to select 
the stimulus effectively.

-dave

> Ron