RE: What does 'last_event really return?

Arpad,

When defining the AMS extensions, we took a minimalist approach, adding to the VHDL 
language only what was necessary. We found that 'LAST_EVENT returning REAL was essential 
for modeling piecewise linear sources and similar models, particularly if elegance and 
efficiency was desired. Hence we added it to the language. Conversely, we found no need 
for 'LAST_ACTIVE returning REAL, as we could not find any cases where the activity of a 
signal (or more precisely the time since it was last active) was relevant in a continuous 
time context.

If 'LAST_ACTIVE returning REAL satisfies a modeling need that we overlooked, then by all 
means it should be added to the language. Otherwise, we may want to revisit whether the 
minimalist approach is still adequate, or whether another philosophy should be applied in 
defining language extensions.

Thanks.
Ernst Christen

On Wed, 15 Feb 2006 23:01:36 -0800, Muranyi, Arpad wrote:
> Peter,
>
> Thanks for your reply.  I hope this oversight will/can
> be corrected in the next rev of the book (if there is
> one planned).
>
> The inconsistency you mentioned is really interesting,
> especially with such similar attributes.  Do you know
> of any plans for making such things more consistent in
> future revs of the language?
>
> Thanks,
>
> Arpad
> ======================================================
>
> -----Original Message-----
> From: Peter Ashenden [mailto:peter@ashenden.com.au]
> Sent: Wednesday, February 15, 2006 4:21 PM
> To: Muranyi, Arpad; vhdl-ams@eda.org
> Subject: RE: What does 'last_event really return?
>
> Arpad,
>
> Thanks for raising the issue in our book. You're right that we overlooked
> the real-valued form of the 'last_event attribute. My aplogies for that.
> Note that, curiously, VHDL-AMS does not also define a real-valued form of
> the 'last_active attribute, only the TIME-valued form from VHDL.
>
> Cheers,
>
> PA
>
> --
> Dr. Peter J. Ashenden                peter@ashenden.com.au
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