Subject: SDL-News: Priority in Enabling Condition
Rajesh_Kumar#ecitele.com
Date: Mon Mar 17 1997 - 11:21:04 GMT
The originator of this message is responsible for its content.
-----From Rajesh_Kumar <rajeshk#cadence.com> to sdlnews -----
Hi,
Please refer to the section about "Enabling condition" in the Z.100 spec of
SDL. It states that ....
"In the case of multiple enabling conditions, these are evaluated
sequentially
in an arbitrary order before entering the state."
The point, I want to make is that if somehow we can specify the order in
which these multiple enabling conditions will be looked at, then it will
help
a great deal in simplifying some of the enabling conditions.
As an example look at the following :
=======================================
/* Assume that i1 is an input signal and
o1, o2, o3 are output signals to the process
*/
PROCESS p1;
dcl Abort, a1_on, a2_on Boolean;
START ;
NEXTSTATE wait;
STATE wait;
INPUT i1;
provided Abort;
output o1;
NEXTSTATE wait;
INPUT i1;
provided ((not Abort) and a1_on);
output o2;
NEXTSTATE wait;
INPUT i1;
provided ((not Abort) and (not a1_on) and a2_on);
output o2;
NEXTSTATE wait;
ENDSTATE;
ENDPROCESS;
=======================================
Here since the order in which the enabling conditions will be evaluated
is not known, so the user has to explicitly write the "(not Abort)" and
"(not Abort and (not a1_on)". Is there any way in which he could have
skipped this explicit specification and written it like the following:
====================
STATE wait;
INPUT i1;
provided Abort;
output o1;
NEXTSTATE wait;
INPUT i1;
provided ( a1_on);
output o2;
NEXTSTATE wait;
INPUT i1;
provided ( a2_on);
output o2;
NEXTSTATE wait;
=========================
This would have been possible say, if some priority could have been
attached with each condition as in Continuos signal, or if there were
a predetermined evaluation order, like top-to-bottom, say.
Thanks and Regards
Rajesh
-----End text from Rajesh_Kumar <rajeshk#cadence.com> to sdlnews -----
For help, email "majordomo#sdl-forum.org" with the body of your email as:
help
or (iff this does not answer your question) email:
owner-sdlnews#sdl-forum.org
This archive was generated by hypermail 2a23 : Sun Jun 16 2013 - 10:41:39 GMT