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Re: [f-cpu] the wrong way (or not?) concerning FP



On Tue, 28 Aug 2001, Yann Guidon wrote:

> hi,
> 
> Juergen Goeritz wrote:
> > What do you mean by complex operations?
> > sqrt(), log(), cos(), sin(), ...?
> 
> "simple" operations are fadd/fsub and fmul.
> of course the conversion operations are necessary
> (FP<->int, truncation, fractional part...) and should be
> simple (at least most of them).

Oops, I forgot about the conversion functions... :-]

> However, for the first FC0s, the fdiv and fsqrt will have to
> be emulated with a "invalid opcode" trap.

Everything that's not included must be emulated like this anyway ;-)

> > So why divide into integer and floating unit? Add those
> > basic floating functionality to *the* f-cpu unit.
> i think that it will be complex, if you mean what i have
> understood. But you can remember that the register set
> stores all kinds of data, so the FP EU can not be taken
> outside of the F-CPU core. So there is no "division".

Is there no opcode left for fdiv inside the f-cpu?

> last time i searched, i found some informations about FP unit
> design. i even posted a web page about it. that's a good starting
> point if you want to volunteer. What we need now is fadd/fsub
> and fmul in IEEE 32-bit and 64-bit format. From that, we can
> derive all the rest.

I took a look into the links you mailed. Haven't seen much
about a good division though. I will concentrate on the 64 bit
version, because 32bit is derivable from this.

JG

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