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

In A.8.4 in primary, we could replace

   concatenation

with

   concatenation select

and in 11.4.12, we could extend 

   "The concatenation is treated as a packed vector of bits"

to say

   ", one or more of which can be selected, assuming an [n-1:0]
numbering."


Also, in 11.4.12, what's the reason for the following text?

  "Software tools can generate a warning if the concatenation width on
one side of an assignment is different from the expression on the other
side. The following examples can give warning of size mismatch"

Why would a software tool need this special permission from the LRM to
issue a warning?  In my opinion, unless a warning is mandated, it
shouldn't be mentioned in the LRM.

-- Brad


-----Original Message-----
From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
Bresticker, Shalom
Sent: Monday, November 05, 2007 7:12 PM
To: Gordon Vreugdenhil
Cc: sv-bc@eda.org
Subject: RE: [sv-bc] part selects on arbitrary expressions

no problem 

> -----Original Message-----
> From: Gordon Vreugdenhil [mailto:gordonv@model.com]
> Sent: Monday, November 05, 2007 11:58 PM
> To: Bresticker, Shalom
> Cc: sv-bc@server.eda.org
> Subject: Re: [sv-bc] part selects on arbitrary expressions
> 
> I'd much rather keep this down to a simpler change, especially coming 
> in this late in the game.  I think I can accept the "select of a 
> concat" as a non-lval expression, but not much more at this point.
> 
> Gord.
> 
> 
> Bresticker, Shalom wrote:
> > 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
> >>>
> >>> --
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> >>>
> >> 
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> > 
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> --
> --------------------------------------------------------------------
> Gordon Vreugdenhil                                503-685-0808
> Model Technology (Mentor Graphics)                gordonv@model.com
> 
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