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Re: [f-cpu] FPU Adder....



Le Mardi 30 Décembre 2003 21:03, Michael Riepe a écrit :
> Ok, here we go...
>
> Nicolas Boulay wrote:
> [...]
>
> > "En" signal  must not be in the process sensitivity list of a clocked
> > process.
>
> Why not?

There is no use of it. A synchrone process could only wake up by the clock and 
by the asynchronous reset. So a modification of "En" wake up the process. So 
you use more simulation time. Sometimes you could also have very strange side 
effect du to delta cycle.

>
> >           while (S5MP(MSIZE) /= '1') loop
> > 		              S5EP := fl_decr(S5EP);
> > 		             	S5MP(MSIZE downto 1) := S5MP(MSIZE-1 downto 0);
> > 		             	S5MP(0) := '0';
> > 		            end loop;
> >
> > Dynamic loop can't be synthetised. Synthetiser unroll such loop but can't
> > do anything with that. It look like it need a clock but which one ? If
> > you want to use loop use only argument that end the loop that can be
> > decided at compile time.
>
> Well, you're right, but...
>
> This looks like part of a normalization circuit to me (shift operand
> left until the MSBit is 1). There already is such a circuit inside the
> integer divide unit.
>

i don't look at it. We definitly need a synthetiser. synopsys say no. Just 
"manage with universities" :/

nicO

> Haven't looked at the source yet, though.
>
> Michael.

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