/// <returns>Instruction successful</returns>
public bool StepForward()
{
if (index == -1)
{
return(false);
}
// Save current machine state
prevStates.AddLast(new MachineState(index, Registers, Stack));
if (prevStates.Count >= MaxStates)
{
prevStates.RemoveFirst();
}
// Execute next instruction
Instruction inst = file.Instructions[index];
bool success = inst.Execute(Registers, Stack, ref index);
// Skip comments
while (0 <= index && index < file.Instructions.Count && file.Instructions[index] is Comment)
{
index++;
}
// Detect end of program
if (index >= file.Instructions.Count)
{
index = -1;
}
OnInstructionReady?.Invoke(index, success);
return(success);
}
/// <returns>Successful (always true)</returns>
public bool Start(int startIndex)
{
index = startIndex;
prevStates = new LinkedList <MachineState>();
OnInstructionReady?.Invoke(index, true);
return(true);
}
/// <returns>Instruction successful (true if a previous state exists, false otherwise)</returns>
public bool StepBackward()
{
if (prevStates.Count == 0)
{
return(false);
}
MachineState last = prevStates.Last();
last.Restore(Registers, Stack);
prevStates.RemoveLast();
index = last.InstIndex;
OnInstructionReady?.Invoke(index, true);
return(true);
}
/// <returns>Instruction successful (always false)</returns>
public bool Ignore()
{
index++;
OnInstructionReady?.Invoke(index, false);
return(false);
}
