Subject: Re: SDL-News: Priority in Enabling Condition
Richard_Sanders#ecitele.com
Date: Mon Mar 17 1997 - 10:18:56 GMT
The originator of this message is responsible for its content.
-----From Richard Sanders <Richard.Sanders#informatics.sintef.no> to
sdlnews -----
Hello Rajesh!
This is not an answer to your question, but a remark: it seems to me that
you want to use Enabling condition for things that are easily handled in
states or by using conditions in SDL.
In your example, you can choose to model the values of Abort and a1/a2 as
states (with corresponding signal output on reception of i1), OR, if you
fear state explosion, to use conditions (informally: if Abort then output o1
else if a1_on output 02 else if a2_on output o2;).
At 17:27 97.03.17 +0531, Rajesh_Kumar wrote:
..
>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
>
Good luck with your SDL modeling!
..................................................................
Richard T. Sanders Richard.Sanders#informatics.sintef.no
SINTEF Telecom and Informatics Telephone: (+47) 73 59 30 06
N-7034 Trondheim, Norway Telefax: (+47) 73 53 25 86
Private: Aasbakken 1, N-7043 Trondheim. (+47) 73 52 06 71
http://www.sintef.no/ or http://www.informatics.sintef.no/~richards
-----End text from Richard Sanders <Richard.Sanders#informatics.sintef.no>
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