RE: [sv-ec] mantis item 1681 - global clocking

Hello All,

Here are my comments on 1681.

1. A new keyword "global" is specified.
   Has SV-AC thoroughly explored overloaded usage of existing
   keywords in order to avoid this keyword inflation?

2. The BNF in the A.6.11 excerpt (near the start of the proposal)
   and the Annex A modifications should have "global" highlighted
   in red, since it would now be a keyword.

3. I don't understand $global_clock very well.
   First, as Neil points out, there are no system functions that
   return "event expression".  I'm not sure in what context the
   system function could be legally called.  And I'm not sure
   of the intended usages.  Could this be clarified by adding
   more rigorous normative description, as well as examples?

4. In 17.3, there is the requirement that users make sure all
   clocks have their ticks aligned with the global clock.
   This requirement is hazy.  What does it mean to be aligned?
   What about clocks that have higher frequencies than the
   global clock?  What if those other clocks aren't even used
   in assertions in the design, and they have different phases,
   frequencies, and duty cycles?  This requirement needs 
   more tightening, and corner cases must all be handled.
   Also, small grammar point:  "In case when the global clocking..."
   should be "In case global clocking..."

5. In 17.14, Clock resolution, I think the new section b) is
   redundant with the new section a).  Did you intend to strike
   out the new section b with red-strikethrough font?

6. In 15.12, there is a sentence that starts "It is an error if...".
   This should be changed to "It shall be an error if..."
   (The sentence appears in the paragraph right after the
   brief clocking_declaration := syntax)

Thanks and regards,
Doug


> -----Original Message-----
> From: owner-sv-ec@server.eda.org 
> [mailto:owner-sv-ec@server.eda.org] On Behalf Of Neil Korpusik
> Sent: Wednesday, February 28, 2007 6:45 AM
> To: SV_EC List
> Cc: Havlicek John-r8aaau
> Subject: [sv-ec] mantis item 1681 - global clocking
> 
> The svac has put up a proposal for mantis item 1681 that 
> introduces the notion
> of a global clocking. This proposal contains changes to 
> clause 15. Clocking Blocks.
> The svec should be reviewing this proposal to ensure that it 
> doesn't have any
> issues with it.
> 
> It appears that the svac has just started to review the proposal.
> 
> I suspect that there will be feedback from the svec on this proposal.
> For one thing, I noticed the following. I might be wrong, but this
> seems to extend the definition of what a function can return.
> 
> 
> "The system function $global_clock returns the event 
> expression specified in the
> global clocking statement."
> 
> 
> -- 
> ---------------------------------------------------------------------
> Neil Korpusik                                     Tel: 408-720-4852
> Senior Staff Engineer                             Fax: 408-720-4850
> Frontend Technologies - ASICs & Processors (FTAP)
> Sun Microsystems
> email: neil.korpusik@sun.com
> ---------------------------------------------------------------------
> 
> 
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