/**
* Here Starts the code of a function according to the given function name that has the given
* number of local variables.
*
* @param numberOfLocals The number of local variables
*/
public void function(short numberOfLocals) throws ProgramException {
short newSP = (short) (getSP() + numberOfLocals);
checkSP(newSP);
workingStackSegment.setStartAddress(newSP);
// disable non relevant range of the local segment - enable only the number
// of locals of this function.
localSegment.setEnabledRange(getSP(), newSP - 1, true);
for (int i = 0; i < numberOfLocals; i++) {
pushValue(MAIN_STACK, (short) 0);
}
String functionName = currentInstruction.getStringArg();
// adds the new function to the top of the call stack.
callStack.pushFunction(functionName);
// sets the static segment range
setStaticRange(functionName);
}
/**
* Executes the current instruction (Program at pc). Returns false if END command, true otherwise.
*/
public void executeInstruction() throws ProgramException {
currentInstruction = program.getNextInstruction();
if (currentInstruction == null) throw new ProgramException("No more instructions to execute");
switch (currentInstruction.getOpCode()) {
case HVMInstructionSet.ADD_CODE:
add();
break;
case HVMInstructionSet.SUBSTRACT_CODE:
substract();
break;
case HVMInstructionSet.NEGATE_CODE:
negate();
break;
case HVMInstructionSet.EQUAL_CODE:
equal();
break;
case HVMInstructionSet.GREATER_THAN_CODE:
greaterThan();
break;
case HVMInstructionSet.LESS_THAN_CODE:
lessThan();
break;
case HVMInstructionSet.AND_CODE:
and();
break;
case HVMInstructionSet.OR_CODE:
or();
break;
case HVMInstructionSet.NOT_CODE:
not();
break;
case HVMInstructionSet.PUSH_CODE:
push(currentInstruction.getArg0(), currentInstruction.getArg1());
break;
case HVMInstructionSet.POP_CODE:
pop(currentInstruction.getArg0(), currentInstruction.getArg1());
break;
case HVMInstructionSet.GOTO_CODE:
goTo(currentInstruction.getArg0());
break;
case HVMInstructionSet.IF_GOTO_CODE:
ifGoTo(currentInstruction.getArg0());
break;
case HVMInstructionSet.FUNCTION_CODE:
if (program.getCurrentPC() == program.getPreviousPC() + 1)
throw new ProgramException("Missing return in " + callStack.getTopFunction());
function(currentInstruction.getArg0());
break;
case HVMInstructionSet.RETURN_CODE:
returnFromFunction();
break;
case HVMInstructionSet.CALL_CODE:
callFunction(
currentInstruction.getArg0(),
currentInstruction.getArg1(),
currentInstruction.getStringArg(),
false);
break;
}
}