Re: sc_pause

Further to this, Bishupriya raised the following issue several years
ago(!)

4.3.4.2 IEEE 1666 defines sc_start(0) to execute ONE delta cycle (Section
4.3.4.2). The refsim implementation has always implemented sc_start(0) to
execute ALL delta cycles at the current time - i.e. sc_start(0) is the
equivalent of the deprecated sc_cycle(0). Excerpts from 1666 and
systemc-2.1v1 RELEASENOTES are given below, along with a simple program
and its output obtained from Systemc-2.2.05jun06_beta release. If the
sc_start(0) call is replaced with sc_cycle(0) in the test, the same output
is obtained with additional deprecation messages for sc_cycle. Which
definition is right in this case? Whichever one is, we have a hole in
expressing the other one, and it seems users may legitimately want to do
both in their designs.

From:
Alan Fitch/doulos
To:
john.aynsley@doulos.com
Cc:
owner-systemc-p1666-technical@eda.org, systemc-p1666-technical@eda.org,
"Jeremiassen, Tor" <tor@ti.com>
Date:
08/11/2010 14:10
Subject:
Re: sc_pause

Hi John,
  a couple of questions:

just to clarify, if I had in sc_main

  sc_start(100, SC_NS); // inside here the code calls sc_pause at say
time = 50 ns
  sc_start (100, SC_NS); // this would resume at 50 ns

Secondly, if I called

   sc_start(SC_ZERO_TIME); // call sc_pause with SC_STOP_IMMEDIATE during
the evaluation phase

  // now what happens? do other runnable processes complete the rest of
the delta above when resumed
  sc_start(1, SC_NS);

regards
Alan

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From: 
john.aynsley@doulos.com 
To: 
systemc-p1666-technical@eda.org 
Cc: 
"Jeremiassen, Tor" <tor@ti.com> 
Date: 
08/11/2010 13:59 
Subject: 
sc_pause 
Sent by: 
owner-systemc-p1666-technical@eda.org
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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