Subject: Re: ns32k toolchain
To: None <ross@netbsd.org>
From: Ian Dall <ian@beware.dropbear.id.au>
List: port-pc532
Date: 08/05/2002 09:26:30
r.o.s.s writes:
> >>:::
> >> This is very similar to what many modern FPUs do, actually. The Alpha
> >> port, for instance, handles things like denorms with a separate
> >> library that Ross Harvey wrote. We might want to use the same library
> >> code where possible across ports for this sort of thing.
> >
> >There is certianly some code which is machine independant, though
> >I don't think it is as easilly seperated as I might hope. The current
> >library for the pc532 is approximately:
> >>:::
>
> FWIW, the indep part of the alpha FP completion project has always
> been in libkern waiting for anyone to call. On alpha. it starts
> over with the original operands and does the entire op in software
> for any case that the running combination of operand value, fpu
> type, and conformance model can't handle.
Yep, I had a quick glance, it seems that the MI part for the alpha is
essentially softfloat.
I took a slightly different tack for the pc532. We scale de-normal operands
so they won't trap, do the operation and rescale. I think this is considerably
"tighter" than using softfloat, certainly it is less code. Of course, the
disadvantage is that there is no support for the case of pc532's without
fpu's. I don't think any were built like that though.
Ian