/**
* Calls a function according to the given function number stating that the given number of
* arguments have been pushed onto the stack
*
* <p>If callerIsBuiltIn then the caller is a builtIn function that called this function through
* callFunctionFromBuiltIn. If address is -1 then a native function should be looked up and
* called.
*/
public void callFunction(
short address, short numberOfArguments, String functionName, boolean callerIsBuiltIn)
throws ProgramException {
stackFrames.addElement(new Integer(workingStackSegment.getStartAddress()));
workingStackSegment.setStartAddress(getSP() + 5);
if (callerIsBuiltIn) {
pushValue(MAIN_STACK, VMProgram.BUILTIN_FUNCTION_ADDRESS);
} else {
pushValue(MAIN_STACK, program.getPC());
}
pushFromRAM(MAIN_STACK, Definitions.LOCAL_POINTER_ADDRESS);
pushFromRAM(MAIN_STACK, Definitions.ARG_POINTER_ADDRESS);
pushFromRAM(MAIN_STACK, Definitions.THIS_POINTER_ADDRESS);
pushFromRAM(MAIN_STACK, Definitions.THAT_POINTER_ADDRESS);
ram.setValueAt(
Definitions.ARG_POINTER_ADDRESS, (short) (getSP() - numberOfArguments - 5), false);
ram.setValueAt(Definitions.LOCAL_POINTER_ADDRESS, getSP(), false);
// enable in the arg segment only the number of args that were sent to the called function.
argSegment.setEnabledRange(
argSegment.getStartAddress(), argSegment.getStartAddress() + numberOfArguments - 1, true);
if (address == VMProgram.BUILTIN_FUNCTION_ADDRESS) {
// Perform some actions normally done in the function() method
localSegment.setEnabledRange(
localSegment.getStartAddress(),
localSegment.getStartAddress() - 1,
true); // no local variables
callStack.pushFunction(functionName + " (built-in)");
staticSegment.setEnabledRange(0, -1, true); // empty static segment
// Read parameters from the stack
short[] params = new short[numberOfArguments];
for (int i = 0; i < numberOfArguments; ++i) {
params[i] = argSegment.getValueAt(i);
}
// Call the built-in implementation
builtInFunctionsRunner.callBuiltInFunction(functionName, params);
} else if (address >= 0 || address < program.getSize()) {
program.setPC(address);
program.setPC(address); // make sure previouspc isn't pc-1
// which might happen if the calling
// function called this function in the
// last line before the "return" and
// was declared just before this function.
// In this case encountering the "function"
// command will issue an error about
// "missing return"...
} else {
error("Illegal call address");
}
}
/**
* Calls a function according to the given function name with the given parameters from a built-in
* function
*/
public void callFunctionFromBuiltIn(String functionName, short[] params) throws ProgramException {
// Push the arguments onto the stack
for (int i = 0; i < params.length; ++i) {
pushValue(METHOD_STACK, params[i]);
}
callFunction(program.getAddress(functionName), (short) params.length, functionName, true);
}
/** Sets the static segment range according to the the given function (file) name. */
protected void setStaticRange(String functionName) throws ProgramException {
int dotLocation = functionName.indexOf(".");
if (dotLocation == -1) throw new ProgramException("Illegal function name: " + functionName);
String className = functionName.substring(0, dotLocation);
int[] range = program.getStaticRange(className);
if (range == null)
throw new ProgramException("Function name doesn't match class name: " + functionName);
staticSegment.setStartAddress(range[0]);
staticSegment.setEnabledRange(range[0], range[1], true);
}
/**
* Constructs the CPU with given program, RAM, call stack, bus, stack and other memory segments.
*/
public CPU(
VMProgram program,
RAM ram,
CallStack callStack,
Calculator calculator,
Bus bus,
AbsolutePointedMemorySegment stackSegment,
TrimmedAbsoluteMemorySegment workingStackSegment,
MemorySegment staticSegment,
MemorySegment localSegment,
MemorySegment argSegment,
MemorySegment thisSegment,
MemorySegment thatSegment,
MemorySegment tempSegment,
File builtInDir) {
this.program = program;
this.ram = ram;
this.callStack = callStack;
this.calculator = calculator;
this.bus = bus;
this.stackSegment = stackSegment;
this.workingStackSegment = workingStackSegment;
this.staticSegment = staticSegment;
this.localSegment = localSegment;
this.argSegment = argSegment;
this.thisSegment = thisSegment;
this.thatSegment = thatSegment;
this.tempSegment = tempSegment;
segments = new MemorySegment[HVMInstructionSet.NUMBER_OF_ACTUAL_SEGMENTS];
segments[HVMInstructionSet.LOCAL_SEGMENT_CODE] = localSegment;
segments[HVMInstructionSet.ARG_SEGMENT_CODE] = argSegment;
segments[HVMInstructionSet.THIS_SEGMENT_CODE] = thisSegment;
segments[HVMInstructionSet.THAT_SEGMENT_CODE] = thatSegment;
segments[HVMInstructionSet.TEMP_SEGMENT_CODE] = tempSegment;
stackFrames = new Vector();
if (program.getGUI() != null) {
builtInFunctionsRunner = new BuiltInFunctionsRunner(this, builtInDir);
}
}
/** Returns the value of the function to the top of the stack. */
public void returnFromFunction() throws ProgramException {
// make sure that there's somewhere to return to (old local <> 0)
if (stackSegment.getValueAt(Definitions.LOCAL_POINTER_ADDRESS) == 0)
throw new ProgramException(
"Nowhere to return to in "
+ getCallStack().getTopFunction()
+ "."
+ getCurrentInstruction().getIndexInFunction());
// done in order to clear the method stack's contents
workingStackSegment.setStartAddress(getSP());
bus.send(ram, Definitions.LOCAL_POINTER_ADDRESS, ram, Definitions.R13_ADDRESS); // R13 = lcl
bus.send(
stackSegment,
stackSegment.getValueAt(Definitions.LOCAL_POINTER_ADDRESS) - 5,
ram,
Definitions.R14_ADDRESS); // R14 = return address
bus.send(
stackSegment,
getSP() - 1,
stackSegment,
ram.getValueAt(Definitions.ARG_POINTER_ADDRESS)); // *arg = return value
setSP((short) (ram.getValueAt(Definitions.ARG_POINTER_ADDRESS) + 1)); // SP = arg + 1
bus.send(
stackSegment,
ram.getValueAt(Definitions.R13_ADDRESS) - 1,
ram,
Definitions.THAT_POINTER_ADDRESS); // that = *(R13 - 1)
bus.send(
stackSegment,
ram.getValueAt(Definitions.R13_ADDRESS) - 2,
ram,
Definitions.THIS_POINTER_ADDRESS); // this = *(R13 - 2)
bus.send(
stackSegment,
ram.getValueAt(Definitions.R13_ADDRESS) - 3,
ram,
Definitions.ARG_POINTER_ADDRESS); // arg = *(R13 - 3)
bus.send(
stackSegment,
ram.getValueAt(Definitions.R13_ADDRESS) - 4,
ram,
Definitions.LOCAL_POINTER_ADDRESS); // lcl = *(R13 - 4)
// removes the top function from the call stack
callStack.popFunction();
// check whether there is a "calling frame"
if (stackFrames.size() > 0) {
// retrieve stack frame address of old function
int frameAddress = ((Integer) stackFrames.lastElement()).intValue();
stackFrames.removeElementAt(stackFrames.size() - 1);
workingStackSegment.setStartAddress(frameAddress);
// disable non relevant range of the local segment - enable only the locals
// of the function that we returned to.
localSegment.setEnabledRange(
Math.max(localSegment.getStartAddress(), Definitions.STACK_START_ADDRESS),
frameAddress - 1,
true);
// enable in the arg segment only the number of args that were sent to the function
// that we returned to.
argSegment.setEnabledRange(
argSegment.getStartAddress(), localSegment.getStartAddress() - 6, true);
// enable this, that according to their retrieved pointers
thisSegment.setEnabledRange(
Math.max(thisSegment.getStartAddress(), Definitions.HEAP_START_ADDRESS),
Definitions.HEAP_END_ADDRESS,
true);
thatSegment.setEnabledRange(
Math.max(thatSegment.getStartAddress(), Definitions.HEAP_START_ADDRESS),
Definitions.SCREEN_END_ADDRESS,
true);
} /* else {
error("Nowhere to return to");
} */
// Allow return if we previously had "function" even with no call -
// For the SimpleFunction test
short returnAddress = ram.getValueAt(Definitions.R14_ADDRESS);
if (returnAddress == VMProgram.BUILTIN_FUNCTION_ADDRESS) {
staticSegment.setEnabledRange(0, -1, true); // empty static segment
builtInFunctionsRunner.returnToBuiltInFunction(popValue(METHOD_STACK));
} else if (returnAddress >= 0 && returnAddress < program.getSize()) {
// sets the static segment range
if (stackFrames.size() > 0) {
setStaticRange(callStack.getTopFunction());
} else {
staticSegment.setStartAddress(Definitions.VAR_START_ADDRESS);
staticSegment.setEnabledRange(
Definitions.VAR_START_ADDRESS, Definitions.VAR_END_ADDRESS - 1, true);
}
program.setPC((short) (returnAddress - 1)); // set previousPC correctly
program.setPC(returnAddress); // pc = *sp
} else {
error("Illegal return address");
}
}
/**
* Enters an infinite loop requested by a built-in function, de-facto halting the program.
* important so that tests and other scripts finish counting (since a built-in infinite loop
* doesn't count as steps). also needed because there is no good way to use the stop button to
* stop an infinite loop in a built-in jack class. A message containing information may be
* provided (can be null).
*/
public void infiniteLoopFromBuiltIn(String message) {
program.setPCToInfiniteLoopForBuiltIns(message);
}
/** Pops a value from the stack and goes to the given address if the value is not zero. */
public void ifGoTo(short address) throws ProgramException {
if (popAndReturn() != 0) {
program.setPC(address);
}
}
/** Goes to the label at the given address */
public void goTo(short address) {
program.setPC(address);
}
/**
* 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;
}
}
