State-machine based logic simulation using three logic values

The inversion algorithm is an event-driven logic simulation technique that is competitive with levelized compiled code simulation even at extremely high activity levels. Previous versions of the algorithm have been limited to two-valued simulation. The three-valued inversion algorithm represents a radical redesign of the algorithm to permit three-valued simulation. The three-valued scheduling technique is significantly more complex than that of the two-valued algorithm, as is the procedure for collapsing simultaneous events. The three-valued algorithm is also capable of converting portions of the simulation from three-valued to two-valued once stable binary values have been achieved. This permits significant enhancements in the performance of the algorithm. Experimental data shows that, like the two-valued algorithm, the three-valued algorithm is competitive with two-valued levelized compiled code simulation.