RE: Question on 'above

I am sure the ABOVE attribute applies to both the quantity and
the threshold.

Jianxin

> -----Original Message-----
> From: owner-vhdl-ams@eda.org [mailto:owner-vhdl-ams@eda.org] On Behalf
Of
> Muranyi, Arpad
> Sent: Thursday, August 24, 2006 3:52 PM
> To: vhdl-ams@vhdl.org
> Subject: Question on 'above
> 
> Hello Everyone,
> 
> Sorry if this forum in not the right place to ask this question, but I
> am not
> sure where else I could ask it.  Does the LRM specify how simulators
> should
> handle the following wait statement:
> 
>     TestAbove : process is
>     begin
>       Count <= Count + 1;
>       wait on SomeRealQuantity'above(SomeRealSignal);
>     end process TestAbove;
> 
> when there is another process that can change the value of
> SomeRealSignal?
> 
> For example, let's assume that when this process stops on the wait
> statement,
> the value of SomeRealSignal is 1.0 and the value of SomeRealQuantity
is
> 0.0,
> therefore the 'above returns a FALSE.  For simplicity, let's also
assume
> that
> the quantity SomeRealQuantity is not changing.  Some time later
another
> process decides to change the value of SomeRealSignal to -1.0.  Is
this
> change supposed to cause the 'above statement change to TRUE and get
the
> waiting process out of wait, or should it remain false until the
> quantity
> goes below and above the signal's new value?  In other words, is the
> 'above
> attribute supposed to act on both its argument and quantity in "real
> time",
> or only on the quantity?
> 
> If you haven't guessed it yet, the reason I am asking this is because
> two
> different vendor's tools give me different results because of this.
> 
> Thanks,
> 
> Arpad
>
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