RE: sc_pause

Tor, All,

I too agree with David's idea to add a recommendation that sc_stop()
should be called from sc_main() with the reason that it will cause
end_of_simulation() to be called.

Is everyone okay with using sc_stop_mode for sc_pause?

Given a call to sc_pause() within sc_start(T), T>0, what should be the
value of simulation time? As Alan suggested, I would propose that it is
the time of the pause rather than +T.

I think we do have an issue to resolve regarding sc_pause() with
SC_STOP_IMMEDIATE. What happens to any runnable processes that were
pre-empted by the sc_pause()? Are they deleted from the set of runnable
processes, or do those processes remain runnable on a subsequent call to
sc_start()? Is this perhaps a reason to NOT support sc_stop_mode for
sc_pause, but to insist that the current delta cycle is completed before
returning from sc_start?

Thanks,

John A

From:
"Jeremiassen, Tor" <tor@ti.com>
To:
David C Black <dcblack@xtreme-eda.com>, John Aynsley
<john.aynsley@doulos.com>
Cc:
P1666 Technical WG <systemc-p1666-technical@eda.org>
Date:
09/11/2010 18:46
Subject:
RE: sc_pause

I agree with the proposal. David?s idea has merit.
 
Tor
 

---
Tor Jeremiassen, Ph.D.
Simulation and Modeling CTO
SDO Foundational Tools
Texas Instruments                    Ph:    281 274 3483
P.O. Box 1443, MS 730                Fax:   281 274 2703
Houston, TX 77251-1443               Email: tor@ti.com
From: owner-systemc-p1666-technical@eda.org [
mailto:owner-systemc-p1666-technical@eda.org] On Behalf Of David C Black
Sent: Monday, November 08, 2010 9:04 AM
To: John Aynsley
Cc: P1666 Technical WG
Subject: Re: sc_pause
 
I'm good with the proposal. It might be good to add a clarifying statment:
 
sc_stop() should be called within sc_main if a decision is made not to 
resume (sc_start) simulation. This allows end_of_simulation() callbacks to 
be properly invoked.
 
NOTE: I would probably add the following code after the last sc_start() as 
a matter of best practices:
 
if (sc_get_status() && SC_PAUSED) {
  SC_REPORT_WARNING(MSGID, "Simulation stopped running from SC_PAUSED");
  sc_stop();
} 
 
On Nov 8, 2010, at 7:59 AM, john.aynsley@doulos.com wrote:
Folks, 
The next topic to finish off is the addition of sc_pause and sc_get_status
, as originally proposed by Tor. We got to the point of being almost ready 
to close this discussion months ago. I  summarize the current proposal 
below. Please give this your careful consideration and either vote "yes" 
or raise any objections you may have. 
Thanks, 
John A 
Add a function sc_pause that is similar to sc_stop except that it puts 
simulation into the paused state. Simulation can be restarted from the 
paused state by calling sc_start again. 
sc_pause uses sc_stop_mode to determine precisely when to pause (or we 
could introduce a new sc_pause_mode, if people wish) 
sc_pause leaves the simulation time at its current value such that 
sc_start would continue from that time 
On return from  sc_start without sc_stop having been called, the 
simulation is left in the paused state. On return from  sc_start after 
sc_stop has been called, the simulation is left in the stopped state. In 
either case, simulation will remain in the running state until all 
processes have ceased executing prior to the return from sc_start 
Make a change to the scheduler spec such that on return from sc_start() 
due to event starvation, the simulation time remains at the time of the 
last event. This can only come about after every process has either 
terminated or executed wait(...) with no time-out. 
When paused, sc_is_running() shall return true. 
Change the LRM such that sc_is_running() is not obliged to return false 
when called from a destructor; sc_is_running would return true unless 
sc_stop had been called 
Add a global function sc_get_status whose value is a bit mask, used as 
follows: 
if (sc_get_status() & (SC_PAUSED | 
                                        SC_STOPPED | 
                                        SC_END_OF_SIMULATION) ) 
      ... 
The full list of simulation phases is: 
        SC_ELABORATION 
        SC_BEFORE_END_OF_ELABORATION 
        SC_END_OF_ELABORATION 
        SC_START_OF_SIMULATION 
        SC_RUNNING 
        SC_PAUSED 
        SC_STOPPED 
        SC_END_OF_SIMULATION 
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