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Re: [f-cpu] Re: optionnal instruction



Michael Riepe a écrit :
> 
> On Sun, Aug 19, 2001 at 09:55:25AM +0800, Glenn Alexander wrote:
> 
> > I'm new here, but aren't we developing a concept implimentation called FC-0
> > and is complicating matters with 128-bit FP really useful at this stage? This
> > is (i understand) intended to be a general  purpose processor so shouldn't we
> > be looking at general purpose cases that apply to normal users? I think if a
> > special application needs 128 (or more) FP, they are more likely at this
> > stage to be on a purpose-built mainframe. Later that may be different, but
> > later FC1 will be done (hey, lets be optimistic) and since the F-architecture
> > is already designed to go above 64-bits, implimenting a full 128 (or more)
> > F-CPU is just something you do.
> 
> There are, in general, two reason why one wants large floating-point
> types.  One of them is precision (as some of you mentioned, that's a
> rather rare case), the other (and more important) one is the increased
> range.  People often use IEEE double not because they need >6 digit
> precision but because single has only 8 bits for the exponent -- and
> sometimes 11 bits aren't enough either.
> 
> But I agree with you: there's no need to worry about FP with more than
> 64 bits for the FC0.  In fact, the FC0 may not have FP hardware at all
> (it's all optional, IIRC).
> 

Yep, but we need to defined precisely the group of insrtruction to be
defined. I think is to difficult to handel a compiler if almost all
instruction could remove or not. I propose an FP group, a mul group
(large interger unit : mul+divide?). I think it could have other
proposal.

nicO

> --
>  Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
>  "All I wanna do is have a little fun before I die"
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