RE: [sv-ec] 890 scheduling algorithm questions

 
Cliff,

Thanks for the update, my phone was disconnected for 3 hours and I had
no internet connection.
We experienced a severe storm where I live that probably caused this.
Anyways, I will forward this email to the cc committee.

Francoise
    '
-----Original Message-----
From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
Clifford E. Cummings
Sent: Monday, April 16, 2007 9:05 PM
To: sv-ec@eda-stds.org; michael.rohleder@freescale.com
Subject: Re: [sv-ec] 890 scheduling algorithm questions

Hi, Francoise -

We discussed your email in the SV-EC meeting today. Arturo answered most
of the questions in his previous email response.

Concerning the feedback arrow from the Post-Observed PLI Region. We
added this based on the idea that the PLI committee might want to do a
callback that would write a variable that could trigger additional
activity. We also added the note:
NOTE - The PLI currently does not schedule callbacks in the
Post-Observed region.

We are going to leave the diagram as is as part of Mantis 890 for
inclusion in Draft 3, but if the CC committee decides that there should
be no feedback from the Post-Observed Region to the Active Region, feel
free to file a post-draft 3 Mantis item to have it removed.

Regards - Cliff

At 10:44 AM 4/11/2007, Francoise Martinolle wrote:
>The sv-cc discussed the 890 scheduling algorithm picture today and 
>Michael Rohleder asked the following questions:
>
>1) There is a loop back to the active region from the pre-NBA, NBA and 
>post-NBA regions. This presumes that when a PLI callback wakes up in 
>the pre-NBA region for ex, the pli user code may schedule an event into

>the active region queue.
>The interpretation from the picture lead us to understand that if that 
>it is the case (an event has been scheduled from the pli pre-NBA region

>in the active region), the active region queue is processed once the 
>pre-NBA events have been processed, before moving to processing the NBA

>region events.
>
>Michael wants to get the confirmation that this is the correct 
>interpretation and that has not changed since 1364.
>
>2) same issue for the loop back for the NBA and post-NBA regions
>
>3) There is a loop back from the observed and post-observed regions to 
>the active region There is no loop back from the pre-observed to the 
>active region and the text explicitly states that it is illegal to 
>write values or schedule an event from that region:
>
>9.3.3.5 Pre-Observed region
>
>"it is illegal to write values to any net or variable or to schedule an

>event within
>
>the current time slot."
>Why this discrepancy?
>If those regions are "read only" as the text states , why is there a 
>loop back to active?
>
>Extract from mantis 890:
>
>9.3.2.5 Observed events region
>
>The Observed region is for evaluation of property expressions when they

>are triggered.
>
>During property evaluation, pass/fail code shall be scheduled in the 
>Reactive region of
>
>the current time slot. PLI callbacks are not allowed in the Observed
region.
>
>9.3.3.6 Post-Observed PLI region
>
>The Post-Observed region provides for a PLI callback control point that

>allows PLI
>
>application routines to read values after properties are evaluated (in 
>the Observed or an
>
>earlier region).
>
>Francoise
>        '
>
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----------------------------------------------------
Cliff Cummings - Sunburst Design, Inc.
14314 SW Allen Blvd., PMB 501, Beaverton, OR 97005
Phone: 503-641-8446 / FAX: 503-641-8486
cliffc@sunburst-design.com / www.sunburst-design.com Expert Verilog,
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