Estimate the initial state of signals in simulation

[Danil Sokolov]

STG and circuit simulation show the state of signals, which are initially undefined (? symbol). Eventually, when a transition of a signal fires the state is set accordingly. Sometimes it is confusing, especially if it is obvious what the initial state of a signal should be.

Try to estimate the initial state of the signals and set them undefined only if this is truly necessary (e.g. if a signal is inconsistent and can be in any state).