bind order

[romi]

Hi,

The 1800-2005 LRM (p.299) says that if multiple bind statements are
present for a given scope, the order of those statements is not
important. This would seem to prevent bind instances from
hierarchically referencing nets in other bind instances.

bind target_mod bind_mod0 bind_inst0 ();
bind target_mod bind_mod1 bind_inst1 (.some_port(bind_inst0.some_net);

Above, I'm showing instantiation of bind_inst1 trying to make a
relative hierarchical reference to a net in bind_inst0. However, this
is illegal (I think since it doesn't work in my tool).

Does anyone know why the LRM didn't just make the bind order important
so this type of referencing would work? The order of other
instantiations is important, why not bind instantiations?

Thanks!

 

[Jonathan Bromley]

On Sun, 23 Nov 2008 21:40:19 -0800 (PST), romi wrote:

The 1800-2005 LRM (p.299) says that if multiple bind statements are
present for a given scope, the order of those statements is not
important. This would seem to prevent bind instances from
hierarchically referencing nets in other bind instances.

I suspect it is rather a good idea to forbid such things.

bind target_mod bind_mod0 bind_inst0 ();
bind target_mod bind_mod1 bind_inst1 (.some_port(bind_inst0.some_net);

This has nothing to do with bind order. In an ordinary module
instance, a cross-module reference to a signal in some other
instance would be resolved at elaboration, and there would be
no need for "bind_inst0" to exist at the time the instance
of bind_inst1 is compiled.

Such usage is, surely, very poor style. It creates a
dependency between the bind-instantiation of bind_inst1 and
that of bind_inst0. If you really must do this, I think it
would make more sense to create a third module containing
normal (not bind) instances of bind_mod0 and bind_mod0, with
the appropriate connection between them, and then bind an
instance of this single wrapper module into your target.
--
Jonathan Bromley, Consultant

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