A Methodology for Hardware Veri cation Based on Logic Simulation

1991 Abstract A logic simulator can prove the correctness of a digital circuit if it can be shown that only circuits fulllling the system speciication will produce a particular response to a sequence of simulation commands. This style of veriication has advantages over other proof methods in being readily automated and requiring less attention on the part of the user to the low-level details of the design. It has advantages over other approaches to simulation in providing more reliable results, often at a comparable cost. This paper presents the theoretical foundations of several related approaches to circuit veriication based on logic simulation. These approaches exploit the three-valued modeling capability found in most logic simulators, where the third value X indicates a signal with unknown digital value. Although the circuit veriication problem is NP-hard as measured in the size of the circuit description, several techniques can reduce the simulation complexity to a manageable level for many practical circuits.