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