RE: [sv-ac] SVA: What is the defintion of "identical clock"?

Ed,
Sorry, but I still don't undertand "syntactically identical"?
Is "assign clk1 = clk2; " identical?
What if I write
assign my_sig = FFa && clk2; // FFa is from a FF
If some properties and blocks use clk1, clk2, and my_sig then I believe this would result in errors.
Can you site cases where 2 clocks are identical?
I see as identical:
- clocks with the same periods where the posedges occur at the same time (and delta time in terms of vhdl sense), but may be of different symetries (0 time and 1 time).
- ??

Ben

In a message dated 10/27/2004 11:12:24 AM Eastern Daylight Time, "Eduard Cerny" <Eduard.Cerny@synopsys.com> writes:

>Defining semantic identity could be quite tricky. Perhaps we could just
>state that the clocks should be syntactically identical. The tools can do
>better if so desired.
>
>ed
>
>
>> -----Original Message-----
>> From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org]On Behalf Of
>> VhdlCohen@aol.com
>> Sent: Tuesday, October 26, 2004 8:39 PM
>> To: sv-ac@eda.org
>> Cc: stuart@sutherland-hdl.com; cliffc@sunburst-design.com
>> Subject: [sv-ac] SVA: What is the defintion of "identical clock"?
>>
>>
>> The LRM discusses at great length the issue of "identical" or
>> "non-identical" clocks, but the LRM fails anywhere to define what
>> is an "identical clock". LRM Std P1364 also fails to define identical.
>> Specifically, Identical in what way? The exact same signal? The
>> same period? Identical in some other way? Is clk1 aliased to clk2
>> identical? Are signals connected via a module port so that they
>> are the same signal? Does "assign clk1=clk2;" create identical clocks?
>>
>> Below is a typical reference in the LRM to identical clocks.
>> LRM 17.12.1 Multiply-clocked sequences states the following:
>> "
>> @(posedge clk0) sig0 ##1 @(posedge clk1) sig1
>> ....
>> If clk0 and clk1 are identical, then the clocking event does not
>> change after ##1 and the above sequence is equivalent to the
>> singly-clocked sequence
>> @(posedge clk0) sig0 ##1 sig1
>>
>> Thanks,
>> Ben Cohen
>> --
>>
>
>

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