Re: [myhdl-list] Re: VCD generation bug

[David B. <dav...@fr...>]

Selon Jan Decaluwe <ja...@ja...>:

> David Brochart wrote:
> > There is a bug in the generation of the VCD file. In the following ex=
ample:
> >
> > ---------------------------------------------------------------------=
------
> >
> > from myhdl import intbv, Signal, Simulation, delay, traceSignals
> >
> > def gen(a):
> >     while 1:
> >         a.next =3D 0
> >         yield delay(10)
> >         a.next =3D 1
> >         yield delay(10)
> >
> > def dummy(a):
> >     b =3D Signal(intbv(0))
> >     b_i0 =3D gen(b)
> >     return b_i0
> >
> > def test():
> >     a =3D Signal(intbv(0))
> >     a_i0 =3D gen(a)
> >     dummy_i0 =3D dummy(a)
> >     return a_i0, dummy_i0
> >
> > test =3D traceSignals(test)
> > sim =3D Simulation(test)
> > sim.run(100)
> >
> > ---------------------------------------------------------------------=
------
> >
> > You can see in the generated VCD file that several signals have the s=
ame
> > identifier.
>
> There are 2 signals, so there should be two different identifiers,
> right? That's also what I see in the VCD definition area, so I'm not su=
re
> there's a problem here.
>
> > Also, signals in "a_i0" are not traced.
>
> Yes, there was a bug in _extractHierarchy.py. Attached the current vers=
ion
> that probably solves it. (As I had solved this already some time ago, I
> think it's about time I'll do a maintenance release...)
>
> Jan
>
> --
> Jan Decaluwe - Resources bvba - http://jandecaluwe.com
> Losbergenlaan 16, B-3010 Leuven, Belgium
>     Python is fun, and now you can design hardware with it:
>     http://jandecaluwe.com/Tools/MyHDL/Overview.html
>


Here is the relevant part we get in the VCD file:

$scope module test $end
$var real 1 ! a $end
$scope module dummy_i0 $end
$var real 1 ! a $end
$var real 1 " b $end
$scope module b_i0 $end
$var real 1 " a $end
$upscope $end
$upscope $end
$upscope $end

The thing is that we have the same identifier for "a" in "test" and "a" i=
n
"dummy_i0", and also for "b" in "dummy_i0" and "a" in "b_i0", which is ri=
ght
because they are really the same signals. But somehow the version of GTKW=
AVE I
run on Linux doesn't like it and doesn't display the waves properly. Whic=
h is
strange because with another version of GTKWAVE on Solaris it works fine.=
 Maybe
we should give a unique identifier for every signal even if some of the s=
ignals
are actually the same?

David.