implemented Clrwdt Instruction (#34)

Co-authored-by: Darkress <30271678+DarkressX@users.noreply.github.com>
Reviewed-on: darkress/pic16f84-sim#34

de/darkress/pic16f84sim/commands/Clrwdt.java

@@ -0,0 +1,24 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.*;
+
+public class Clrwdt extends LiteralCommandUtils implements Command
+{
+
+    public Clrwdt()
+    {
+    }
+
+    @Override
+    public void execute()
+    {
+        ProgramCounter.incPC();
+        Cycles.incCycles();
+
+        Memory.setRegister(0x03, Memory.getRegister(0x03) | 0x18);
+        if(Timer.getPrescalerAssignment()) {
+            Timer.resetTimeToTimerIncrease();
+            Watchdog.resetWatchdogTimer();
+        }
+    }
+}

de/darkress/pic16f84sim/decoder/CommandDecoder.java

@@ -97,7 +97,7 @@ public class CommandDecoder
 
         if (input == 0x0064)
         {
-            //clrwdt();
+            return new Clrwdt();
         }
 
         if (input == 0x0009)

de/darkress/pic16f84sim/microcontroller/Watchdog.java

@@ -8,6 +8,10 @@ public class Watchdog
         return watchdogTimer;
     }
 
+    public static void resetWatchdogTimer() {
+        watchdogTimer = 18000;
+    }
+
     public static void decreaseWatchdogTimer()
     {
         watchdogTimer--;