[sv-cc] Mantis item 1503: Redoing the formal argument declarations

Bassam,

I have to apologize because, after all the work we did creating the 
sequence formal decl and property formal decl VPI objects and their 
relations, I don't think they're going to work.  As I've studied the 
BNF for sequence declarations and talked to our local assertion 
engineers, I've recognized the following:

-- Our current diagrams don't have any way to represent an initial 
value expression for an untyped formal or for a named event.

-- I'm guessing that an untyped formal could be mapped to either a net 
or a variable (or an event or sequence), so that representing the 
formal argument as any one of them would be too restrictive.

-- In fact, even a typed formal doesn't tell you whether the object is 
a net or a variable.

So I recommend going back to the BNF and doing the following:

-- Call it a "sequence port item" to match the BNF.

-- Give it back its vpiName property (to correspond to the 
port_identifier nonterminal).

-- Have a single arrow relation to a "typespec", with the usual dashed 
outline.  Add a detail that says that the vpiTypespec relation shall 
return NULL if the port item is untyped.

-- Have the vpiExpr relation return the optional sequence actual arg, 
shown as a dashed enclosure around a combination of

   o a sequence expr, and

   o whatever we use to represent an event_expression (I wasn't able to 
figure out how we represent an event_expression in VPI).

I presume we should also do the same kind of thing for a property 
formal decl (== property_port_item).

Let me know if I have misinterpreted any of this.

Thanks,
Jim

--------------------------------------------------------- 
James H. Vellenga                            978-262-6381 
Software Architect                     (FAX) 978-262-6636 
Cadence Design Systems, Inc.         vellenga@cadence.com 
270 Billerica Rd
Chelmsford, MA 01824-4179
"We all work with partial information." 
---------------------------------------------------------- 

-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.