/******************************************************
* CALL: Clicking the step back button.
* TASK: Rolls back the program one step i.e. undo the
* previous operation.
*****************************************************/
private void Button_StepBack_Click(object sender, RoutedEventArgs e)
{
if (_runTimer.IsEnabled)
{
errorCode("Cannot undo while running the application.");
return;
}
if (_assemblerModel.undoStack().size() == 0)
{
errorCode("Nothing to undo.");
return;
}
if (_assemblerModel.undoStack().size() == 1)
{
Keyboard.ClearFocus();
_currentTextBox.Foreground = (Brush)FindResource("TextBoxForegroundOff");
clearUserMsg();
_currentTextBox.IsReadOnly = false;
showButtonAsEnabled(ButtonType.Stop);
}
UndoStorage undoValues = _assemblerModel.undo();
Bit12 currentAddr = _assemblerModel.getAddr(_assemblerModel.instructionPtr());
Operations opr = Operations.LOAD;
_assemblerModel.extractOperation(currentAddr.value(), out opr);
// Mark current row
markRow(getMMRowOfPosition(255 - _assemblerModel.instructionPtr()));
// Update graphics of changed memory
byte index;
if (_assemblerModel.addrIdxToUpdate(currentAddr, out index))
{
if (opr == Operations.RETURN)
{
index += 2;
}
MemoryRow row = getMMRowOfPosition(255 - index);
row.ShowMemoryAdress(_assemblerModel.getAddr(index));
if (index > 250)
{
MemoryRow stackRow = getStackRowOfPosition(255 - index);
stackRow.ShowMemoryAdress(_assemblerModel.getAddr(index));
}
}
ValueRow_WorkingRegister.ShowMemoryAdress(_assemblerModel.workingRegister());
ValueRow_Output.ShowMemoryAdress(_assemblerModel.output());
lightIfOutputIsOn();
ValueRow_InstructionPointer.ShowMemoryAdress(new Bit12(_assemblerModel.instructionPtr()));
}
/******************************************************
* CALL: UndoStorage valuesUndone = undo();
* TASK: Returns an object which contains the previous
* state of various objects.
*****************************************************/
public UndoStorage undo()
{
UndoStorage undoValues = _undoStack.top();
_undoStack.pop();
_memory = undoValues._memory;
_memoryStack = undoValues._memoryStack;
_instructionPtr = undoValues._instructionPtr;
_workingRegister = undoValues._workingRegister;
_output = undoValues._output;
return(undoValues);
}