An integrated approach to state assignment and sequential element selection for FSM synthesis

The state encodings and the type of sequential elements have a significant impact on the combinational logic area of a synthesized FSM. Unlike most of the existing approaches, the algorithm presented in this paper does both state assignment and sequential element selection (D and T type flipflops) so as to realize area efficient FSMs. The synthesis problem modelled as an optimization problem has been solved using a stochastic evolution based algorithm. A cost function having a good correlation with the synthesized area has been developed. The paper presents a D-domain transformation technique that enables this cost function to evaluate FSMs using non D type flipflops. The results over 17 MCNC FSM benchmarks show that the integrated approach using D and T type flipflops consistently gives lesser area than one or more of the existing state assignment schemes