From 31cd0d1b4b6cc5009f681dea692c17ed9303464a Mon Sep 17 00:00:00 2001
From: hneemann <helmut.neemann@arcor.de>
Date: Sat, 20 Aug 2016 20:24:29 +0200
Subject: [PATCH] refactored the add-sub dependency

---
 .../neemann/digital/core/arithmetic/Add.java  | 22 ++++++++++++++-----
 .../neemann/digital/core/arithmetic/Sub.java  |  5 ++---
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/main/java/de/neemann/digital/core/arithmetic/Add.java b/src/main/java/de/neemann/digital/core/arithmetic/Add.java
index 061191e79..f75ce9c3d 100644
--- a/src/main/java/de/neemann/digital/core/arithmetic/Add.java
+++ b/src/main/java/de/neemann/digital/core/arithmetic/Add.java
@@ -29,10 +29,10 @@ public class Add extends Node implements Element {
     private final ObservableValue sum;
     private final ObservableValue cOut;
     private final long mask;
-    protected ObservableValue a;
-    protected ObservableValue b;
-    protected ObservableValue cIn;
-    protected long value;
+    private ObservableValue a;
+    private ObservableValue b;
+    private ObservableValue cIn;
+    private long value;
 
     /**
      * Create a new instance
@@ -49,7 +49,19 @@ public class Add extends Node implements Element {
 
     @Override
     public void readInputs() throws NodeException {
-        value = a.getValue() + b.getValue() + cIn.getValue();
+        value = calc(a.getValue(), b.getValue(), cIn.getValue());
+    }
+
+    /**
+     * Performs the add operation
+     *
+     * @param a a
+     * @param b b
+     * @param c carry
+     * @return the result
+     */
+    protected long calc(long a, long b, long c) {
+        return a + b + c;
     }
 
     @Override
diff --git a/src/main/java/de/neemann/digital/core/arithmetic/Sub.java b/src/main/java/de/neemann/digital/core/arithmetic/Sub.java
index 9cb09520f..b78c25e7a 100644
--- a/src/main/java/de/neemann/digital/core/arithmetic/Sub.java
+++ b/src/main/java/de/neemann/digital/core/arithmetic/Sub.java
@@ -1,6 +1,5 @@
 package de.neemann.digital.core.arithmetic;
 
-import de.neemann.digital.core.NodeException;
 import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.core.element.ElementTypeDescription;
 import de.neemann.digital.core.element.Keys;
@@ -31,7 +30,7 @@ public class Sub extends Add {
     }
 
     @Override
-    public void readInputs() throws NodeException {
-        value = a.getValue() - b.getValue() - cIn.getValue();
+    protected long calc(long a, long b, long c) {
+        return a - b - c;
     }
 }