Addlw instruction (#4)

* Added addlw command

* Write to program list

* Included CommandUtils as helpter class. Sorted classes into packages

* Revert changes on HelloWorld

* Revert "Revert changes on HelloWorld"

This reverts commit a08a336864fb2aa2bbc5a4e37ca360765774965e.

* Added example execution of Addlw command

commands/Addlw.java

@@ -0,0 +1,25 @@
+package commands;
+
+import registers.Memory;
+
+public class Addlw extends CommandUtils implements Command
+{
+    private final int literal;
+
+    public Addlw(int input)
+    {
+        literal = input & 0x00FF;
+    }
+
+    @Override
+    public void execute()
+    {
+        int result = literal + Memory.workingRegister;
+
+        checkZeroBit(result);
+        checkCarryBit(result);
+        checkDigitCarryBit(result, literal);
+
+        Memory.workingRegister = result % 256;
+    }
+}

commands/Command.java

@@ -0,0 +1,6 @@
+package commands;
+
+public interface Command
+{
+    void execute();
+}

commands/CommandUtils.java

@@ -0,0 +1,33 @@
+package commands;
+
+import registers.Memory;
+
+public class CommandUtils
+{
+    protected void checkZeroBit(int result)
+    {
+        if(result == 0){
+            Memory.setZeroBit();
+        } else{
+            Memory.clearZeroBit();
+        }
+    }
+
+    protected void checkCarryBit(int result)
+    {
+        if(result > 255){
+            Memory.setCarryBit();
+        } else{
+            Memory.clearCarryBit();
+        }
+    }
+
+    protected void checkDigitCarryBit(int result, int literal)
+    {
+        if(((Memory.workingRegister & 0x0F) + (literal & 0x0F)) > 15){
+            Memory.setDigitCarryBit();
+        } else{
+            Memory.clearDigitCarryBit();
+        }
+    }
+}