RE: Question on 'above

John,

Thanks for your reply.  Unfortunately it didn't answer my
question.  I would like to know the time of the evaluation
of this comparison (as I explained it to you in my private
email).  Should it only happen when the Q is calculated,
or also when S is calculated?

I would also like to make a respectful request to Peter
Ashenden and the rest of the authors of the famous VHDL-AMS
book "The System Designer's Guide to VHDL-AMS" to revisit
the sections which mention 'above, because they are a little
misleading in saying:  "The result is a Boolean signal that
is true when the value of the quantity is greater than the
expression value and false otherwise" (pg. 204).  (There
may be multiple locations where this is stated).  The output
of 'above will only become false when the quantity is less
than the expression, but not when it is equal to it.

I apologize for talking about the book here... this will be
my last message on this subject.

Sincerely,

Arpad
============================================================

-----Original Message-----
From: John Shields [mailto:John_Shields@mentor.com] 
Sent: Thursday, August 24, 2006 4:31 PM
To: Muranyi, Arpad; 1076.1 mailing list
Subject: Re: Question on 'above

Hi Arpad,

 Q'ABOVE(E) is an implicit boolean signal.  The wait is waiting on this 
signal to change and it is only sensitive to this signal.  As you 
described it, there would be an event on this signal going from false to 
true.  because Q is 0 and E goes from 1 to -1.  The LRM defines it:

Q'ABOVE(E)
Kind: Signal.
Prefix: Any scalar quantity denoted by the static name Q.
Parameter: An expression of the same type as Q. Any quantity appearing 
in the expression must be denoted by a static name.
Result Type: Type BOOLEAN.
Result: TRUE if Q - E is sufficiently larger than 0.0, FALSE if Q - E is 
sufficiently smaller than 0.0,
            Q'ABOVE(E)'DELAYED otherwise.

I believe the Result definition is meant to imply that if Q - E is not 
sufficiently different from 0, the signal does not change value.  There 
is no event.  Hope that helps.

Regards, John