Subject: SDL-News: Transition atomicity and tool behavior
Philippe_Leblanc#ecitele.com
Date: Tue Apr 29 1997 - 19:45:20 GMT
The originator of this message is responsible for its content.
-----From Philippe Leblanc <leblanc#tlse.verilog.fr> to sdlnews -----
Following previous emails on transition atomicity, this is
how the ObjectGEODE Simulator operates:
Process transitions (from an input to a next state)
are executed in an atomic way. It means that
as soon as a transition is fired, all the actions (tasks, outputs,
timer sets, etc.) are performed within the same step.
When the next state is reached, the simulator evaluates
all the fireable transitions (a fireable transition roughly
corresponds to the presence of a consumable signal in a
process queue or a continuous signal set to true).
In Interactive mode, the human operator selects the transition
he/she wants to fire. In Exhaustive mode (for validation
purpose), the simulator will investigate ALL the combinations.
It means that in a given system state, if 3 independent transitions
are fireable, the simulator will build 6 (= 3!) paths in the system
state graph, corresponding to all the possible combinations.
Note 1: Import expressions introduce intermediate states.
Note 2: We have added a priority mechanism between
processes that reduces possible combinations of
transition executions.
Note 3: Process queues can be bounded in the Simulator
by means of so-called filter conditions.
So, in the OG Simulator, the process instances run in a
pseudo-parallelism mode -- there is no interleaving
between transition symbols - but the interleaving is
completely taken into account at transition level.
Hope that helps, and sorry for this late answer.
Philippe Leblanc
--Tel.: +33 (0)5 61 19 29 33
Switchboard: +33 (0)5 61 19 29 39
Fax: +33 (0)5 61 40 84 52
Email: leblanc#verilog.fr
VERILOG S.A.
BP 1310
F-31106 Toulouse Cedex - France
-----End text from Philippe Leblanc <leblanc#tlse.verilog.fr> to sdlnews
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