RE: [sv-bc] minor wire issues

From: Rich, Dave <Dave_Rich_at_.....>
Date: Mon Jul 02 2007 - 10:45:23 PDT
Then why did we need uwire?

________________________________

From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On
Behalf Of Brad Pierce
Sent: Monday, July 02, 2007 8:45 AM
To: sv-bc@server.eda.org
Subject: Re: [sv-bc] minor wire issues


Yes, wire and tri are "identical in their syntax and functions", but
according to 6.10.1, "two names are provided so that the name of a net
can indicate the purpose of the net in that model."
 
It goes on to say, "A wire net can be used for nets that are driven by a
single gate or continuous assignment. The tri net type can be used where
multiple drivers drive a net."
 
What's so wrong about assuming that the designer has accurately
indicated the purpose of the net with the choice of wire  vs. tri, hence
that 
 
            tri [15:0] busa;
 
is indeed "a three-state 16-bit bus"?
 
-- Brad

________________________________

From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
Bresticker, Shalom
Sent: Monday, July 02, 2007 2:42 AM
To: sv-bc@eda.org
Subject: [sv-bc] minor wire issues


  

Hi,

A few minor issues related to tri's and uwire's.

1. 6.8.1 has the example: tri [15:0] busa; // a three-state 16-bit bus
This is not accurate. tri is exactly the same as wire. It may or may not
be three-state.

 

2. 6.10.1 describes tri and wire. 
6.10.2 describes wired-and and wired-or nets. 
6.10.3 describes triregs. 
6.10.4 describes tri0 and tri1. 
6.10.5 describes uwires.

I think uwires are closer to plain wires than any of those other
variants, so I think the uwire sub-clause should immediately follow
6.10.1 instead of being several sub-clauses distant.

 

3. 10.3.4 Continuous assignment strengths

The driving strength of a continuous assignment can be specified by the
user. This applies only to assignments

to scalar nets of the following types:

wire tri trireg

wand triand tri0

wor trior tri1

This omits uwires. In fact, it would be easier to write

This applies only to assignments to scalar nets, except of type supply0
and supply1.

 

4. Annex L: vpiTri has the comment /* three-state net */. This is not
accurate. tri is exactly the same as wire. It may or may not be
three-state.

 

Shalom Bresticker

Intel Jerusalem LAD DA

+972 2 589-6852

+972 54 721-1033 

 


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Received on Mon Jul 2 10:45:52 2007

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