[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [f-cpu] Re: Floating-Point?



On Tue, Aug 14, 2001 at 03:25:04PM +0200, Yann Guidon wrote:
> hi !
> 
> Juergen Goeritz wrote:
> > On Mon, 13 Aug 2001, Yann Guidon wrote:
> > > > do you have a link to basic floating point implementations
> > > > that can be used to begin with a pipeline fpu unit?
> > >
> > > There are some docs floating around on Internet but nothing
> > > that could do the trick for the FC0 (due to its specific structure).
> > > superpipeline + SIMD is not easy to do.

SIMD is IMHO not reasonable for the FP units.  A reasonable approach is
to build a set of pipelined 64-bit FP units, and then issue the 32-bit
operations in two consecutive cycles.

BTW: I think we need another instruction that converts 32-bit FP to 64-bit
and vice versa (and maybe also does the mix/expand/sdup thingy for FP).

While we're at it: something that I miss in most CPUs is `variable'
register addressing, that is, accessing a register when its number
is not known at compile time -- like get and put in the F-CPU, but for
ordinary registers.  I know that this is likely to cause trouble with the
scheduler, but what about mirroring the general registers in the SR area
and simply use get and put?

-- 
 Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
 "All I wanna do is have a little fun before I die"
*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/