RE: FW: Question on 'above

Mr Kamran is right that implicit signals are updated at step d) of the simulation cycle, 
but only if they are active. My previous explanation takes this into consideration, and it 
is based on the relevant section of the LRM about how signals become active and an 
understanding of who owns the driver of a signal of the form Q'Above(E).

Ernst Christen

On Sat, 26 Aug 2006 23:12:11 -0700, Muranyi, Arpad wrote:
> Thank you Mr. Kamran for your reply.  Unfortunately
> this answer contradicts what Ernst wrote in his reply
> on the VHDL-AMS reflector (see message below).  Since
> I do not have a copy of the IEEE document, I cannot
> look it up, so I need to ask the question, which answer
> is correct?
>
> Thanks,
>
> Arpad
> =============================================================
> -----Original Message-----
> From: owner-vhdl-ams@server.eda.org [mailto:owner-vhdl-ams@server.eda.org] On Behalf 
Of Ernst Christen
> Sent: Thursday, August 24, 2006 5:35 PM
> To: Muranyi, Arpad
> Cc: vhdl-ams@server.vhdl.org
> Subject: Re: Question on 'above
>
> Hi Arpad,
>
> As John Shields described, an event will happen when the expression Q - E changes sign.
> The basic question is when does the event happen. I assume you expect it to happen at 
the
> same time as the event on SomeRealSignal. This is not what the LRM describes. Since the
> driver of the 'ABOVE signal is owned by the analog kernel, the crossing event can only
> happen after the analog kernel has determined an ASP, because only then does it perform
> the crossing check. Now, if you study the simulation cycle, you will find that the 
analog
> solver determines another ASP only under two conditions: either the break flag is set, 
or
> Tn > Tc in step a). In the latter case the ASPs do not include Tc (the ASP at this time
> has already been determined), so you will get the crossing event at a later time than 
the
> event on SomeRealSignal. The only way to get what you want is to execute a break 
statement
> when the event occurs on SomeRealSignal. This tells the analog solver that there is a
> discontinuity on one of the waveforms it is in control of, the waveform
> SomeRealQuantity-SomeRealSignal.
>
> Thanks.
> Ernst Christen
> =============================================================
> -----Original Message-----
> From: kamran@cad.ece.ut.ac.ir [mailto:kamran@cad.ece.ut.ac.ir]
> Sent: Saturday, August 26, 2006 1:11 AM
> To: Muranyi, Arpad
> Cc: zainalabedin@navabi.com
> Subject: Re: FW: Question on 'above
>
>
> Hello,
> According to LRM, evaluation of implicit signal associated with
> q'above(s)occurs in both cases,when Q is calculated,and also when S is
> calculated. you can see page 174 of LRM ( IEEE Std 1076.1-1999 ). part d
> of simulation cycle gurantees that  evaluation of the implicit signal
> associated with q'above occurs any time S has some changes.
>
> Regards
> A. Kamran