RE: [sv-ac] Samppled value functions

i Dmitry,
 
mantis #1737 does some additional corrections, but the discrepancy with
the formal part would still be there. I think that the formal semantics
should be changed. 
 
Regards,
ed
 


________________________________

	From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf
Of Korchemny, Dmitry
	Sent: Tuesday, May 29, 2007 7:42 AM
	To: sv-ac@eda-stds.org
	Subject: [sv-ac] Samppled value functions
	
	

	Hi all,

	 

	There is some inconsistency between the LRM body and the formal
semantics. According to LRM (clause 16.8.3):

	 

	A value change function detects the change in the sampled value
of an expression. The clocking event is

	used to obtain the sampled value of the argument expression at a
clock tick prior to the current simulation

	time unit. Here, the current simulation time unit refers to the
simulation time unit in which the function is

	evaluated. This sampled value is compared against the value of
the expression determined at the Preponed

	time of the current simulation time unit. The result of a value
change expression is true or false and can be

	used as a boolean expression.

	- $rose returns true if the LSB of the expression changed to 1.
Otherwise, it returns false.

	- $fell returns true if the LSB of the expression changed to 0.
Otherwise, it returns false.

	- $stable returns true if the value of the expression did not
change. Otherwise, it returns false.

	When these functions are called at or before the first clock
tick of the clocking event, the results are computed

	by comparing the current sampled value of the expression to X.

	 

	while according to the formal semantics (annex F.4), all these
functions return false when called before the first tick of the clocking
event.

	 

	Thanks,

	Dmitry


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