CustomFloat

[Paul D. Anderson]

Paul D. Anderson Wrote:

> Andrei Alexandrescu Wrote:
> 
> > I found myself in need for smaller and specialized floating point types, 
> > where I configure the exact configuration (sign, mantissa, exponent, 
> > bias). See http://en.wikipedia.org/wiki/Half_precision for a half 
> > precision number slated for inclusion in IEEE 754r.
> > 
> > Would it be interesting to add a CustomFloat template to phobos? I'm 
> > thinking along the lines of:
> > 
> > template CustomFloat!(bool sign, uint mantissa,
> >          uint exponent, uint bias)
> > {
> >      ...
> > }
> > 
> > So half-precision numbers are:
> > 
> > alias CustomFloat!(true, 5, 10, 15) HalfFloat;
> > 
> > There are quite a few details to kink out but this is definitely doable. 
> > Numbers like 24-bit floating point and even 8-bit floating point would 
> > be easy to support too. For now CustomFloat would be intended 
> > exclusively as a compact storage mechanism; only conversion to the 
> > standard floating points would be implemented. Later, maybe we can get 
> > to implement some operations natively at least on machines that support 
> > them in hardware. I wanted to gauge interest in the topic.
> > 
> > 
> > Andrei
> 
> I've done some work on a set of decimal floating point numbers consistent with the new 754r decimal formats approved in June. Some of that work would be applicable here, I think.
> 
> It would probably make sense to add the decimal formats at the same time. Let me know if I can help.
> 
> Paul
> 

Here's a link to info regarding the decimal formats: http://speleotrove.com/decimal/