implemented Xorlw Instruction

de/darkress/pic16f84sim/commands/Xorlw.java

@@ -0,0 +1,22 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+
+public class Xorlw extends CommandUtils implements Command
+{
+    private final int literal;
+
+    public Xorlw(int input)
+    {
+        literal = input & 0x00FF;
+    }
+    @Override
+    public void execute()
+    {
+        int result = literal ^ Memory.workingRegister;
+
+        checkZeroBit(result);
+
+        Memory.workingRegister = result % 256;
+    }
+}

de/darkress/pic16f84sim/microcontroller/ProgramCounter.java

@@ -15,4 +15,9 @@ public class ProgramCounter
     {
         ProgramCounter.PC = PC;
     }
+
+    public static void incPC()
+    {
+        PC++;
+    }
 }