| Summary: | 碩士 === 淡江大學 === 資訊工程研究所 === 81 === Several approaches have been proposed in study of communica-
ting concurrent systems , such as asynchronous models : Petri-
Nets , CSP , CCS ,and synchronous models : Esterel ,
Statecharts , Lustre and Signal . One significant
implementation upon those models is to design reactive systems
, e.g. , nuclear power sys- tems , flight control systems , etc
, react to external stimuli (signals) continuously and never
terminate . There are some problems for such embedded systems
to face , for instance , nondeterminism (output signals could
compete with concurrent input signals) , blowing-up states (in
parallelism) . One of the approaches to solve the
nondeterminism problem is to assume that reactions are
instantaneous and atomic . This as- sumption is referred to as
strong synchrony assumption . To achieve such a goal , we can
simply assume that every ac- tion does not take time . Under
this assumption , the relation between stimuli and reactions
become clear and deterministic . Moreover , declaration of
incompatable relations(mutually exclu- sive relations) over
signals and local signals together with st- rong synchrony
assumption can greatly reduce the number of sta- tes in solving
state explosion problem . Based on strong synchrony assumption
and declaration of state reduction relations over signals , we
present a static analysis to translate a synchronous program
written in Esterel into a de- sired sequential deterministic
finite automaton (DFA). To arrive such a goal , a set of
computable conditions is explored and a corresponding algorithm
is given to merge DFAs of sequential mo- dules which are
parallelly composed into a DFA for the whole sy- stem such that
the resulted DFA can run on a single processor and leads to the
same results of strong synchrony assumption as the machine runs
infinitely fast . Finally , the implementation and analysis of
the algorithm is also given in the thesis .
|
|---|
