RE: [sv-ec] Mantis 1702 - queue concatenation

From: Jonathan Bromley <jonathan.bromley_at_.....>
Date: Tue Nov 13 2007 - 05:58:02 PST
Shalom,

thanks for the various comments.

> For background, see http://www.eda-stds.org/sv-ec/hm/3482.html .

Yes.  The scheme I've suggested deals with all Dave Rich's 
points, I think, but it forbids directly-nested queue
concatenations because the items in a queue concat are not
individually an assignment-like context.  I tried to be
ultra-conservative with this; we just don't have time to
get bogged down in disambiguating anything complicated.
I'm willing to keep things really simple, provided we
can rescue queue-concat behaviour as shown in the
clause 7 examples.

From your second email:

> There is the sentence "Queues and dynamic arrays have the same
> assignment and argument passing semantics," which implies 
> that you could probably assign a queue concatenation to
> a dynamic array, and a dynamic array to a queue.

I specifically suggested getting rid of that sentence,
because I think it opens too many doors to pain.
Again I'm being as conservative as I dare.

> Your proposal would only allow queue concatenations to appear in an
> assignment to a queue. That does not mean I'm opposed. I'm just trying
> to figure out implications of the proposal.

Again, purely conservatism.  It may be possible to extend the
queue-concat mechanism to other arrays, so that you can
build an array value out of a mixture of slices and elements.
It may also be possible to allow assignment from any kind
of unpacked array expression to any other (queue -> dynamic,
etc).  But I don't want to risk delaying this proposal by 
introducing such generality right now.  A restrictive 
proposal can easily be relaxed in the future; a subtly 
broken proposal would be a backward step.
-- 
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, 13 Nov 2007 13:58:02 -0000

This archive was generated by hypermail 2.1.8 : Tue Nov 13 2007 - 05:58:55 PST