## Hierarchical Finite State Machines with Multiple Concurrency Models (1999)

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Venue: | IEEE Transactions on Computer-aided Design of Integrated Circuits and Systems |

Citations: | 133 - 40 self |

### BibTeX

@ARTICLE{Girault99hierarchicalfinite,

author = {Alain Girault and Bilung Lee and Edward A. Lee},

title = {Hierarchical Finite State Machines with Multiple Concurrency Models},

journal = {IEEE Transactions on Computer-aided Design of Integrated Circuits and Systems},

year = {1999},

volume = {18},

pages = {742--760}

}

### Years of Citing Articles

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### Abstract

This paper studies the semantics of hierarchical finite state machines (FMS's) that are composed using various concurrency models, particularly dataflow, discrete-events, and synchronous/reactive modeling. It is argued that all three combinations are useful, and that the concurrency model can be selected independently of the decision to use hierarchical FSM's. In contrast, most formalisms that combine FSM's with concurrency models, such as Statecharts (and its variants) and hybrid systems, tightly integrate the FSM semantics with the concurrency semantics. An implementation that supports three combinations is described.

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Citation Context ...ter than zero) that return the FIFO queues to the same size that they were at the beginning of the iteration. Unfortunately, for general DF graphs, it is undecidable whether a finite iteration exists =-=[12]-=-. Moreover, there may not be a unique minimum set of actor firings. To get around these problems, we specialize further to a subclass of DF called synchronous dataflow (SDF) [31], reviewed below, for ... |

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Citation Context ...tation that are significantly different from that of Statecharts. Specification and description language (SDL) combines process networks with FSM’s [4]. The codesign finite state machine (CFSM) mode=-=l [16] combi-=-nes FSM’s with a discrete-event (DE) concurrency model. Pankert et al. combine synchronous DF [31] with FSM’s [40], [36]. Program-state machines (PSM) combine imperative semantics with FSM’s [39... |

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Citation Context ...ard, in principle. The functions are simply evaluated in any order until we converge to a fixed point. Choosing a good order for evaluating the functions can greatly impact performance, obviously. In =-=[20]-=-, Edwards proposes and compares several algorithms for choosing a good order of evaluation. Functions are allowed to change between ticks. Thus, a module in SR has two distinct behaviors that we call ... |

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Citation Context ...mbines FSM’s with a discrete-event (DE) concurrency model. Pankert et al. combine synchronous DF [31] with FSM’s [40], [36]. Program-state machines (PSM) combine imperative semantics with FSM’s =-=[39], [43]-=-. Hybrid systems [1], [24] mix concurrent continuous-time systems (usually given as differential equations) with finite automata. Simulink, from The MathWorks, Inc. (Nattick, MA), provides a simulatio... |

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Citation Context ...g and resource usage. We study, therefore, two popular concurrency models that are more tightly synchronized, DE and SR. The formal relationship among all of these models of computation is studied in =-=[33]. -=-1 In [29], an actor may also assert what the token values must be. It is a simple exercise to show that omitting this capability does not compromise Turing completeness. Moreover, for reactive FSM’s... |

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Citation Context ...any years in widely used computer-aided design (CAD) packages. Synthesis of hardware (e.g., [46]) and software (e.g., [10]) from SDF graphs has been demonstrated. Synthesis of hardware (e.g., [9] and =-=[41]-=-) and software (e.g., [8]) from SR has also been demonstrated. Given our simple composition semantics, it is not hard to come up with ways to combine independently synthesized components. Although sti... |

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Citation Context ...process networks with FSM’s [4]. The codesign finite state machine (CFSM) model [16] combines FSM’s with a discrete-event (DE) concurrency model. Pankert et al. combine synchronous DF [31] with FS=-=M’s [40], -=-[36]. Program-state machines (PSM) combine imperative semantics with FSM’s [39], [43]. Hybrid systems [1], [24] mix concurrent continuous-time systems (usually given as differential equations) with ... |

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Citation Context ...odel of computation is strict, but specific models can override this behavior. A. The Reflex Game VI. EXAMPLES A commonly used example for control-intensive software environments is the “reflex game=-=” [7]-=-. Our version of the reflex game is a two-player game (to introduce more concurrency). 1) Description of the Game: The inputs to the system are coin, ready, go, stop and time. All but the last are use... |

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Citation Context ...del of computation and ellipses indicate states in an FSM. A. Termination In general, the systems of interest may not terminate. Concurrent models of computation are usually defined with this in mind =-=[17]-=-. The reaction of an FSM, however, will usually need to take finite time. This means that if a state refines to a concurrent subsystem, that subsystem must react in finite time to the inputs, possibly... |

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