Re: [sv-bc] E-mail Ballot: Respond by 8am PDT, Tuesday, March 25

Daniel,

2-state nets were the subject of 1800-2005 ballot issue 228, as
discussed in

   http://www.eda.org/sv-bc/hm/7823.html

According to a bug note in the associated Mantis item 694 --

------------
On April 21, 2005 the SV-BC voted to accept the following resolution:

"The committee read and considered this feedback. While it has merit,
the committee believes it is either not feasible to implement at this
time or not in the scope or goals of the P1800 project as it was defined
& agreed upon by the P1800 WG"

Brad Pierce dissented. He would like to see this feature included in the
LRM.
------------

-- Brad


-----Original Message-----
From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
Steven Sharp
Sent: Tuesday, April 01, 2008 4:05 PM
To: shalom.bresticker@intel.com; sv-bc@eda.org; danielm@aldec.com.pl
Subject: RE: [sv-bc] E-mail Ballot: Respond by 8am PDT, Tuesday, March
25


>From: "danielm" <danielm@aldec.com.pl>

>The problem is what should happened when port kind is net (basing on
rules
>defined in yours doc) but data type is fobbidden for a wire (ie all 2
val
>types and others)

>I was asking about this before and as i remmeber it is not defined and
>currently tool dependent - maybe this probposal is good place to make
this
>clear.

It is currently illegal.  It is just that certain tools do not enforce
that, and have their own nonstandard ways of dealing with it.


>There are 3 solutions:
>- always forbid such code - syntax error

That is the case now.


>- allow 2val types to be a net.

There was some discussion of this toward the end of the 2005 standard
development.  A lot of people seemed to think that this would be a
good thing.  However, there was not enough time to reach consensus
and work out all the details.  The effort did not resume after the
2005 standard.


>- if port kind is not given explicitly in such cases change implicitly
the
>kind into variable. If kind is given explicitly print an error

The problem with this is that we may eventually allow 2-state types on
nets.  Then we would either be stuck with this rule that no longer makes
any sense, or would have to change the behavior, which would not be
backward compatible.

By making this case illegal for now, we can decide what to do with it
later, without having to worry about backward compatibility.  If we make
a bad decision now, then we are stuck with it, or have to worry about
backward compatibility.

Steven Sharp
sharp@cadence.com


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