RE: [sv-bc] part selects on arbitrary expressions

Should selects of concatenations be allowed on the left-hand side of
assignments or only on the right-hand side?

Thanks,
Shalom 

> -----Original Message-----
> From: owner-sv-bc@server.eda.org 
> [mailto:owner-sv-bc@server.eda.org] On Behalf Of Brad Pierce
> Sent: Monday, November 05, 2007 7:34 AM
> To: sv-bc@server.eda.org
> Subject: RE: [sv-bc] part selects on arbitrary expressions
> 
> Shalom,
> 
> Yes, I'd be OK with selects of concatenations as a first step 
> for 2008.
> I can imagine someone considering it weird if (a)[0] and a[0] 
> had different results and not so weird if {a}[0] and a[0] did so.
> 
> And it's no less convenient to write {a+b}[0] than (a+b)[0].
> 
> BTW would {a+b}[0] return the right-most bit?  If we add 
> support for selects of concatenations, we should also make 
> sure that the result of
> type() applied to a concatenation is clearly defined.
> 
> A related nice enhancement would be to allow the 
> concatenation of unpacked operands (of bit-stream types), 
> returning a simple bit vector.
> 
> -- Brad
> 
> -----Original Message-----
> From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com]
> Sent: Sunday, November 04, 2007 7:20 PM
> To: Brad Pierce; sv-bc@eda.org
> Subject: RE: [sv-bc] part selects on arbitrary expressions
> 
> I have been thinking about this for a long time. I believe 
> that the simplest thing to do and the way that has the best 
> chance of being passed within the short time that we have is 
> to define selects on concatenations. There is no ambiguity in 
> that case. It has some limitations, you only have vectors, 
> but I believe it would still add a lot of usefulness.
> 
> Shalom 
> 
> > -----Original Message-----
> > From: owner-sv-bc@server.eda.org
> > [mailto:owner-sv-bc@server.eda.org] On Behalf Of Brad Pierce
> > Sent: Sunday, November 04, 2007 10:50 PM
> > To: sv-bc@server.eda.org
> > Subject: Re: [sv-bc] part selects on arbitrary expressions
> > 
> > Following up to http://www.eda-stds.org/sv-bc/hm/5506.html 
> , I, too, 
> > would like to see this enhancement (selects of arbitrary 
> primaries) in
> 
> > SV-2008.
> >  
> > In SV-2005, for any expression 'expr',  one can already declare
> >  
> >    var type(expr) temp;
> >  
> > and then write
> >  
> >    temp = expr;
> >    ... temp[5] ...
> >  
> > But one ought to be able to simply write
> >  
> >    ... (expr)[5] ...
> >  
> > More generally, for any primary 'p', one ought to be able to write
> >  
> >    ... p[5] ...
> >  
> > Consider the defintion of static cast --
> >  
> >    "If the expression is assignment compatible with the 
> casting type, 
> > then the cast shall return the value that a variable of the casting 
> > type would hold after being assigned the expression."
> >  
> > We could come up with a similar rule that generalizes selects.
> >  
> > I don't think it's a strong argument against this 
> enhancement to say 
> > that the type() operator is not well enough defined, as noted in
> > 
> >          http://www.eda-stds.org/sv-bc/hm/7082.html
> > 
> > To me that is just an argument for clarifying the definition of the
> > type() operator.
> >  
> > -- Brad
> > 
> > --
> > This message has been scanned for viruses and dangerous content by 
> > MailScanner, and is believed to be clean.
> > 
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