[sv-champions] RE: Mantis 3069

Hi Shalom,

The same issue exist for a default clocking in 14.2:
Only one default clocking can be specified in a module, interface, program, or checker. Specifying a default
clocking more than once in the same module, interface, program, or checker shall result in a compiler error.
A default clocking is valid only within the scope containing the default clocking specification statement.
This scope includes the module, interface, program, or checker that contains the declaration as well as any
nested modules, interfaces, or checkers. It does not include instantiated modules, interfaces, or checkers.

It is not clear from here whether a default clocking may be specified in a generate block in a module, etc., and we wanted to clarify this for a global clocking at least. If you think this should be a problem, it should be possible to keep the same language for a global clocking as used for a default one.

Thanks,
Dmitry

From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of Bresticker, Shalom
Sent: Sunday, October 30, 2011 16:28
To: sv-ac@eda-stds.org
Cc: sv-champions@eda.org
Subject: [sv-ac] Mantis 3069

Hi,

I am concerned about the following rule for global clock resolution:

"a) Look for a global clocking declaration in the enclosing (or 'parent' in b)) module, interface, checker, or program instance scope, or a generate block therein."

So for example in the end of the proposal:

"The following example is illegal, because the module top in the elaborated design descritpion contains multiple global clocking declarations.

module top;
global clocking ck1 @(negedge clk);
subsystem sub1();
if (1) begin: b
global clocking ck2 @(posedge clk);
subsystem sub2();
end
endmodule"

The concept that the global clocking top.b.ck2 is considered as if declared in top, and an upward hierarchical search finds declarations in "a generate block therein" does not exist elsewhere in the language as far as I remember. I would be reluctant to break another consistency in the language.

Shalom

Shalom Bresticker
Intel LAD DA, Jerusalem, Israel
+972 2 589 6582 (office)
+972 54 721 1033 (cell)
http://www.linkedin.com/in/shalombresticker

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