Implemented comparison instructions

creature.go

@@ -60,12 +60,36 @@ func (machine *Machine) Execute (offset int) {
 			machine.Push(machine.Pop() / machine.Pop())
 			
 		case 0x8:
-			// EQU
+			// EQ
 			// checks if the last two words on the stack are equal
+			equal := 0
+			if machine.Pop() == machine.Pop() { equal = 1 }
+			machine.Push(equal)
 		
 		case 0x9:
+			// GT
+			// checks if the last word on the stack is greater than
+			// the second to last word on the stack
+			greater := 0
+			if machine.Pop() > machine.Pop() { greater = 1 }
+			machine.Push(greater)
+		
 		case 0xa:
+			// LT
+			// checks if the last word on the stack is less than the
+			// second to last word on the stack
+			less := 0
+			if machine.Pop() > machine.Pop() { less = 1 }
+			machine.Push(less)
+			
 		case 0xb:
+			// NEQ
+			// checks if the last two words on the stack are not
+			// equal
+			notEqual := 0
+			if machine.Pop() != machine.Pop() { notEqual = 1 }
+			machine.Push(notEqual)
+			
 		case 0xc:
 		case 0xd:
 		case 0xe: