RE: [sv-ac] immediate assertions in always_comb

From: Jonathan Bromley <jonathan.bromley_at_.....>
Date: Tue Sep 11 2007 - 03:54:26 PDT
> I am not sure what "variable or select expression that is read" means.
> My interpretation was everything on the right hand side of an
> assignment.

It's definitely not restricted to that;  for example
the expression in an if() or case() test most certainly
must contribute to the block's sensitivity, as would
any expression supplied as an actual argument to a 
function.  I agree that "is read" in the LRM is not 
crystal-clear, which is why I generally re-phrase it 
as "participates in an expression".  I don't think
that distorts the meaning.

The problem gets *much* more interesting if you add
the ability to put concurrent assertions into 
always_comb.  Should the always_comb then be 
sensitised to the *sampled* (Preponed) values
of signals in the assertion?  Should it be 
sensitised to signals in the assertion at all?
Sorry, I haven't read that proposal yet, so
I don't know what has already been suggested
about this.
-- 
Jonathan Bromley, Consultant

DOULOS - Developing Design Know-how
VHDL * Verilog * SystemC * e * Perl * Tcl/Tk * Project Services

Doulos Ltd. Church Hatch, 22 Market Place, Ringwood, Hampshire, BH24 1AW, UK
Tel: +44 (0)1425 471223                   Email: jonathan.bromley@doulos.com
Fax: +44 (0)1425 471573                           Web: http://www.doulos.com

The contents of this message may contain personal views which 
are not the views of Doulos Ltd., unless specifically stated.

-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
Received on Tue Sep 11 03:56:51 2007

This archive was generated by hypermail 2.1.8 : Tue Sep 11 2007 - 03:57:06 PDT