EFSM manipulation to increase high-level ATPG effectiveness

The EFSM paradigm can be efficiently adopted to model complex designs without incurring in the state explosion problem typical of the traditional FSM paradigm. However, traversing an EFSM can be more difficult than an FSM because the guards of transitions involve both primary inputs and internal registers. Hard-to-traverse transitions represent a problem when a simulation-based approach is applied to perform functional validation. In fact, they do not allow a complete exploration of the state space. In this paper, EFSM hard-to-traverse transitions are classified, and a set of transformations is proposed to generate an EFSM model which is easy to be traversed. This allows pseudo-deterministic ATPGs to more uniformly analyze the state space of the resulting EFSM.