Added interrupt support for ACIA

+ Added interrupt support for ACIA
+ Auto-formatting (in case anyone cares)

src/main/java/com/loomcom/symon/devices/Acia6850.java

@@ -43,7 +43,7 @@ public class Acia6850 extends Acia {
 
     static final int STAT_REG = 0;	// read-only
     static final int CTRL_REG = 0;	// write-only
-	
+
     static final int RX_REG = 1;	// read-only
     static final int TX_REG = 1;	// write-only
 
@@ -58,7 +58,7 @@ public class Acia6850 extends Acia {
             case RX_REG:
                 return rxRead(cpuAccess);
             case STAT_REG:
-                return statusReg();
+                return statusReg(cpuAccess);
 
             default:
                 throw new MemoryAccessException("No register.");
@@ -78,7 +78,7 @@ public class Acia6850 extends Acia {
                 throw new MemoryAccessException("No register.");
         }
     }
-    
+
     private void setCommandRegister(int data) {
         // Bits 0 & 1 control the master reset
         if((data & 0x01) != 0 && (data & 0x02) != 0) {
@@ -97,8 +97,8 @@ public class Acia6850 extends Acia {
      * @return The contents of the status register.
      */
     @Override
-    public int statusReg() {
-        // TODO: Parity Error, Framing Error, DTR, DSR, and Interrupt flags.
+    public int statusReg(boolean cpuAccess) {
+        // TODO: Parity Error, Framing Error, DTR, and DSR flags.
         int stat = 0;
         if (rxFull && System.nanoTime() >= (lastRxRead + baudRateDelay)) {
             stat |= 0x01;
@@ -109,7 +109,14 @@ public class Acia6850 extends Acia {
         if (overrun) {
             stat |= 0x20;
         }
-		
+        if (interrupt) {
+            stat |= 0x80;
+        }
+
+        if (cpuAccess) {
+            interrupt = false;
+        }
+
         return stat;
     }
 
@@ -118,6 +125,7 @@ public class Acia6850 extends Acia {
         overrun = false;
         rxFull = false;
         txEmpty = true;
+        interrupt = false;
     }
 
 }