/**
* Sets the message's opcode
*
* @see Opcode
*/
public void setOpcode(Opcode opcode) {
int value = opcode.getValue();
if (value < 0 || value > 0xF)
throw new IllegalArgumentException("DNS Opcode " + value + "is out of range");
flags &= 0x87FF;
flags |= (value << 11);
}
@Override
protected void outputLocalInfo(XmlWriter writer) {
super.outputLocalInfo(writer);
// Opcode
if (opcode != null) writer.write("code", opcode.getID());
// Label
if (label != null) writer.write("label", label);
// Immediate operands
if (reference != null) reference.output(writer);
if ((targets == null) && (operand != null)) writer.write(operand);
// Switch-like instructions
if ((targets != null) && (targets.size() > 0)) {
ReadOnlyCollection<Integer> labels = targets.keys();
for (int key : labels) {
writer.start("target");
writer.write("key", key);
writer.write(targets.get(key));
writer.end("target");
}
if (operand != null) {
writer.start("default");
writer.write(operand);
writer.end("default");
}
}
}
public String toString() {
return String.format("#%d (@%d) %s", index() + 1, offset(), Opcode.forOpcode(opcode()));
}
public void cycle() {
if (halted) {
return;
}
try {
if (ip >= memory.length) {
// Loop back to the beginning of memory
ip = 0;
}
Opcode opcode = Opcode.get(memory[ip++]);
byte flags = 0;
if (opcode.argumentCount > 0) {
flags = memory[ip++];
}
Register reg;
switch (opcode) {
case NOP:
break;
case MOV:
if (argumentType(flags, 0) == ArgumentType.CONSTANT) {
// Memory address
// Note - only the least significant byte is set here
int address = argument(flags, 0);
int value = argument(flags, 1);
memory[address] = (byte) value;
} else if (argumentType(flags, 0) == ArgumentType.REGISTER) {
reg = Register.index(memory[ip++]);
int value = argument(flags, 1);
register(reg, value);
} else {
throw new NonMaskableInterrupt("invalid argument type");
}
break;
case ADD:
reg = Register.index(memory[ip++]);
register(reg, register(reg) + argument(flags, 1));
break;
case SUB:
reg = Register.index(memory[ip++]);
register(reg, register(reg) - argument(flags, 1));
break;
case MUL:
reg = Register.index(memory[ip++]);
register(reg, register(reg) * argument(flags, 1));
break;
case DIV:
reg = Register.index(memory[ip++]);
register(reg, register(reg) / argument(flags, 1));
break;
case PUSH:
push(Register.index(memory[ip++]));
break;
case POP:
pop(Register.index(memory[ip++]));
break;
case APUSH:
push(Register.EDX);
push(Register.ECX);
push(Register.EBX);
push(Register.EAX);
break;
case APOP:
pop(Register.EAX);
pop(Register.EBX);
pop(Register.ECX);
pop(Register.EDX);
break;
case JMP:
ip = argument(flags, 0);
break;
case JEZ:
int jezDest = argument(flags, 0);
if (argument(flags, 1) == 0) {
ip = jezDest;
}
break;
case JNZ:
int jnzDest = argument(flags, 0);
if (argument(flags, 1) != 0) {
ip = jnzDest;
}
break;
case JLZ:
int jlzDest = argument(flags, 0);
if (argument(flags, 1) < 0) {
ip = jlzDest;
}
break;
case JGZ:
int jgzDest = argument(flags, 0);
if (argument(flags, 1) > 0) {
ip = jgzDest;
}
break;
case HWID:
break;
case HLT:
halt();
break;
}
} catch (Exception ex) {
throw new NonMaskableInterrupt(ex);
}
}
/**
* Retrieves the mesasge's opcode
*
* @see Opcode
*/
public Opcode getOpcode() {
return Opcode.valueOf((flags >> 11) & 0xF);
}
