fixed PC

Co-authored-by: Darkress <30271678+DarkressX@users.noreply.github.com>
Reviewed-on: darkress/pic16f84-sim#5

de/darkress/pic16f84sim/commands/Retlw.java

@@ -0,0 +1,22 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+import de.darkress.pic16f84sim.microcontroller.Stack;
+
+public class Retlw extends CommandUtils implements Command
+{
+    private final int literal;
+
+    public Retlw(int input)
+    {
+        literal = input & 0x00FF;
+    }
+
+    @Override
+    public void execute()
+    {
+        Memory.workingRegister = literal;
+        ProgramCounter.setPcFromStack(Stack.pop());
+    }
+}

de/darkress/pic16f84sim/commands/Return.java

@@ -8,6 +8,6 @@ public class Return extends CommandUtils implements Command
     @Override
     public void execute()
     {
-        ProgramCounter.setPcFrom11BitLiteral(Stack.pop());
+        ProgramCounter.setPcFromStack(Stack.pop());
     }
 }

de/darkress/pic16f84sim/decoder/CommandDecoder.java

@@ -110,8 +110,7 @@ public class CommandDecoder
             case 0x3000:
                 return new Movlw(input);
             case 0x3400:
-                //retlw();
-                break;
+                return new Retlw(input);
         }
 
         if ((input | 0x0060) == 0x0060)

de/darkress/pic16f84sim/microcontroller/Memory.java

@@ -59,6 +59,10 @@ public class Memory
         }
         memory[address] = data;
         memory[address + 128] = data; //Ensure data is written to both banks to simulate mapping
+        if(address == 0x2) //Check if PCL is destination
+        {
+            ProgramCounter.loadPc();
+        }
     }
 
     private static int getDataFromIndirectAddress(int address)
@@ -75,6 +79,10 @@ public class Memory
         }
         memory[address % 128] = data; // else: Registers.Registers which are mapped
         memory[address % 128 + 128] = data; //Ensure data is written to both banks to simulate mapping
+        if(address == 0x2) //Check if PCL is destination
+        {
+            ProgramCounter.loadPc();
+        }
     }
 
     private static int getRegisterBank()

de/darkress/pic16f84sim/microcontroller/ProgramCounter.java

@@ -20,19 +20,20 @@ public class ProgramCounter
         pc = (pch) + pcl;
     }
 
+    public static void setPcFromStack(int stack)
+    {
+        pc = stack;
+        Memory.setPCL(pc & 0x00FF);
+    }
+
+    public static void loadPc()
+    {
+        pc = (Memory.getPCLATH() <<8) + Memory.getPCL();
+    }
+
     public static void incPC() //is called after every instruction execution
     {
-        int pcl = Memory.getPCL();
-        int pclath = Memory.getPCLATH();
-        if(pcl == 0xFF)
-        {
-            pclath++;
-            pcl = 0;
-        } else {
-            pcl++;
-        }
-        Memory.setPCL(pcl);
-        Memory.setPCLATH(pclath);
-        pc = (pclath <<8) + pcl;
+        pc++;
+        Memory.setPCL(pc & 0x00FF);
     }
 }