RE: [fpu] Rounding of Floating Point Numbers

["Rudolf Usselmann" <russelmann@hotmail.com>]

>-----Original Message-----
>From: owner-fpu@opencores.org [mailto:owner-fpu@opencores.org]On Behalf
>Of Damjan Lampret
>
> > So I guess I have to implement ALL of those modes :*(
>
>I really care only for default. Afterall other three are optional. So
>if they are optional it means they are optional. Why should they be
>implemented if they are optional? And who is ever changing this
>rounding modes. I don't think other three are even used (at least not
>in 99% of cases).

Actually if you *do* want to claim that your FPU is IEEE-754 compliant
you must implement all four rounding techniques. The spec is very clear
about that. I have worked on IEEE committees before, and know how to read
the sometimes 'stupid' wording of the IEEE specs ;*)

> > Instead of sitting down and figuring this all out, I thought there
> > might be
> > already some white papers or other information that describes the
> > rounding
> > technique and perhaps has some efficient implementation suggestions.
> >
>
>I know what your question was and I might have some answers. Actually
>the book in front of me has them. But I am too lazy to copy a couple of
>pages (and the author of the book wouldn't be too _happy_ about this).
>
>You have a section on FP rounding schemes and how to implement them. I
>can try to extract for default rounding but everything is quite mixed
>together with other rounding schemes (and I am not yet used to typing
>on my new Sony VAIO SuperSlim Pro laptop ;-). If you really need this

This sounds like a cool little thing !!! I had my eyes on it as well, but
choose the Dell. It's huge, but is has a lot to offer (like a 1400*1050 dpi
screen :*).

>I'll try to extract. But for a start I can give you title and author:
>
>Computer Arithmetic
>Algorithms and /hardware designs
>
>Behrooz Parhami
>Oxford University Press, 2000
>ISBN 0-19-512583-5

No, the info you provided is perfect, you don't have to copy any parts of
the book, that would violate copyright etc. If you think the book is good,
I'll order it ...

>regards,
>Damjan

Thanks !!!
rudi

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