while loop

hi,
can anyone tell me while loop is synthesizable with synplify tool or
not?
plz help me out.
hoping a positive reply from all.
thanx.
jiten

jiten

jiten wrote:

> can anyone tell me while loop is synthesizable with synplify tool or
> not?

Since a synthesis process loops all by
itself, every clock tick, I can't
imagine how you would use a while loop.
Let's see the code.

Sequential statements execute in zero time.
They form a testable logical description,
not a real-time program thread.

If you want a time delay, use a counter variable.

-- Mike Treseler

Mike Treseler

hi all,
i've checked while loop without clock & with clock.
but its not getting synthesized with synplify-pro.
however,if i sunthesize with xilinx project manager it
synthesized
completely with all conditions.
Is there any problem with while loop in synplify pro.
plz help me out.
jiten
Mike Treseler wrote:
> jiten wrote:
>
> > can anyone tell me while loop is synthesizable with synplify tool or
> > not?
>
> Since a synthesis process loops all by
> itself, every clock tick, I can't
> imagine how you would use a while loop.
> Let's see the code.
>
> Sequential statements execute in zero time.
> They form a testable logical description,
> not a real-time program thread.
>
> If you want a time delay, use a counter variable.
>
> -- Mike Treseler

jiten

I would be very cautious with ISE results since synplify does a very
good job. check out whether it has actually synthesized or just ignored
it.

Neo

its giving error that "while loop is not terminating", but i tried all
conditions such that it can be terminated easily. even i tried exit
condition also inside the while loop.
what is the problem...............................?
plz help.
thanx

jiten

Hey , in general a while loop is not synthesizable. do the same thing
with an if condition.

Neo

ya, it is working properly with "for" loop.
can any one suggest me how can i do it with while loop.

jiten

hi all,
in sinplfy pro , i m actually getting this error
"while loop is not terminating? you can set the maximum number of
loop
iterations with the syn_looplimit attribute."
what does it means?

jiten

It requires that the number of iterations be fixed, so it should be
deterministic.

Neo

hi the code is like this

process(cnt,tmp,rst)
begin
if rst='1' then
cnt <= "0000";
tmp <= "000";
i <= 0;
else
w : while i< 8 loop
tmp <= tmp+1;
cnt <= cnt+1;
i <= i + 1;
end loop w;
end if;
end process;

jiten