SYMBOLIC 2-LEVEL MINIMIZATION

In this paper, we present a symbolic minimization procedure to obtain optimal two-level implementations of finite-state machines. Encoding b ased on symbolic minimization consists of optimizing the symbolic repr esentation, and then transforming the optimized symbolic description i nto a compatible two-valued representation by satisfying encoding cons traints (bitwise logic relations) imposed on the binary codes that rep lace the symbols, Our symbolic minimization procedure captures the sha ring of product terms due to ORing effects in the output part of a two -level implementation of the symbolic cover, Face, dominance, and disj unctive constraints are generated, Product terms are accepted in a sym bolic minimized cover only when they induce compatible encoding constr aints, At the end, a set of codes that satisfy all constraints Is comp uted, The quality of this synthesis procedure is shown by the fact tha t the cardinality of the cover obtained by symbolic minimization and o f the cover obtained by replacing the codes in the initial cover and t hen minimizing it with ESPRESSO are very close, Experiments show that in some cases, our procedure improves on the best results of state-of- art tools.