Implement UI for the VIA/PIA

src/main/java/com/loomcom/symon/devices/Via6522.java

@@ -25,6 +25,7 @@ package com.loomcom.symon.devices;
 
 import com.loomcom.symon.exceptions.MemoryAccessException;
 import com.loomcom.symon.exceptions.MemoryRangeException;
+import com.loomcom.symon.util.Utils;
 
 /**
  * Skeleton for future implementation of a MOS 6522 VIA.
@@ -56,6 +57,8 @@ public class Via6522 extends Pia {
 
     public Via6522(int address) throws MemoryRangeException {
         super(address, address + VIA_SIZE - 1, "MOS 6522 VIA");
+        outputRegisterA = outputRegisterB = 0;
+        dataDirectionA = dataDirectionB = 0;
     }
 
     @Override
@@ -73,11 +76,11 @@ public class Via6522 extends Pia {
     @Override
     public int read(int address, boolean cpuAccess) throws MemoryAccessException {
         return switch (address) {
-            case IOB_REG    -> pbRead(cpuAccess);
-            case IOA_REG    -> paRead(cpuAccess);
+            case IOB_REG    -> pbRead();
+            case IOA_REG    -> paRead();
             case DDRB_REG   -> dataDirectionB;
             case DDRA_REG   -> dataDirectionA;
-            case IOANH_REG  -> paRead(cpuAccess);
+            case IOANH_REG  -> paRead();
             default -> throw new MemoryAccessException("No Register or Not Implemented!");
         };
     }
@@ -90,20 +93,21 @@ public class Via6522 extends Pia {
         inputRegisterA = data & 0xFF;
     }
 
-    public int getOutputRegisterB() {
-        return outputRegisterB;
+
+    public String getPBStatus() {
+        return "%" + Utils.byteToBin(pbRead());
     }
 
-    public int getOutputRegisterA() {
-        return outputRegisterA;
+    public String getPAStatus() {
+        return "%" + Utils.byteToBin(paRead());
     }
 
-    private int pbRead(boolean cpuAccess) {
+    private int pbRead() {
         // Return bits of output register where DDRB is 1 and input register where DDRB is 0
         return (outputRegisterB & dataDirectionB) | (inputRegisterB & ~dataDirectionB);
     }
 
-    private int paRead(boolean cpuAccess) {
+    private int paRead() {
         // Return bits of output register where DDRB is 1 and input register where DDRB is 0
         return (outputRegisterA & dataDirectionA) | (inputRegisterA & ~dataDirectionA);
     }

src/main/java/com/loomcom/symon/ui/StatusPanel.java

@@ -26,12 +26,13 @@ package com.loomcom.symon.ui;
 import com.formdev.flatlaf.util.UIScale;
 import com.loomcom.symon.Cpu;
 import com.loomcom.symon.CpuState;
+import com.loomcom.symon.devices.Pia;
+import com.loomcom.symon.devices.Via6522;
 import com.loomcom.symon.machines.Machine;
 
 import javax.swing.*;
 import javax.swing.border.Border;
 import javax.swing.border.EtchedBorder;
-import javax.swing.plaf.metal.MetalTextFieldUI;
 import java.awt.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
@@ -71,6 +72,8 @@ public class StatusPanel extends JPanel {
     private JTextField aField;
     private JTextField xField;
     private JTextField yField;
+    private JTextField piaBField;
+    private JTextField piaAField;
 
     private final Machine machine;
 
@@ -153,6 +156,10 @@ public class StatusPanel extends JPanel {
         JLabel xLabel = makeLabel("X");
         JLabel yLabel = makeLabel("Y");
 
+        // PIA/VIA labels
+        JLabel piaBLabel = makeLabel("PB");
+        JLabel piaALabel = makeLabel("PA");
+
         statusFlagsLabel.setToolTipText("6502 Processor Status Flags");
         opcodeLabel.setToolTipText("Instruction Register");
         pcLabel.setToolTipText("Program Counter");
@@ -165,6 +172,9 @@ public class StatusPanel extends JPanel {
         xField = makeTextField(SMALL_TEXT_FIELD_SIZE, true);
         yField = makeTextField(SMALL_TEXT_FIELD_SIZE, true);
 
+        piaBField = makeTextField(LARGE_TEXT_FIELD_SIZE, false);
+        piaAField = makeTextField(LARGE_TEXT_FIELD_SIZE, false);
+
         // Make fields editable
         pcField.addActionListener(new ActionListener() {
             @Override
@@ -287,6 +297,25 @@ public class StatusPanel extends JPanel {
         add(xField, constraints);
         constraints.gridx = 1;
         add(yField, constraints);
+
+        constraints.insets = new Insets(5, 0, 0, 0);
+        constraints.gridx = 0;
+        constraints.gridwidth = 2;
+        constraints.gridy = 10;
+        add(piaBLabel, constraints);
+
+        constraints.insets = new Insets(2, 2, 2, 2);
+        constraints.gridy = 11;
+        add(piaBField, constraints);
+
+        constraints.insets = new Insets(5, 0, 0, 0);
+        constraints.gridy = 12;
+        add(piaALabel, constraints);
+
+        constraints.insets = new Insets(2, 2, 2, 2);
+        constraints.gridy = 13;
+        add(piaAField, constraints);
+
     }
 
     /**
@@ -296,6 +325,8 @@ public class StatusPanel extends JPanel {
         Cpu cpu = machine.getCpu();
         CpuState cpuState = cpu.getCpuState();
 
+        Pia pia = machine.getPia();
+
         // Update the Processor Status Flag display
         int status = cpuState.getStatusFlag();
 
@@ -317,6 +348,12 @@ public class StatusPanel extends JPanel {
         xField.setText(cpu.getXRegisterStatus());
         yField.setText(cpu.getYRegisterStatus());
 
+        // Update the Pia Variables
+        if (pia instanceof Via6522) {
+            piaBField.setText(((Via6522) pia).getPBStatus());
+            piaAField.setText(((Via6522) pia).getPAStatus());
+        }
+
         repaint();
     }
 

src/main/java/com/loomcom/symon/util/Utils.java

@@ -76,6 +76,16 @@ public class Utils {
                                            "F0", "F1", "F2", "F3", "F4", "F5", "F6", "F7",
                                            "F8", "F9", "FA", "FB", "FC", "FD", "FE", "FF"};
 
+    private static final String[] BIN_CONSTANTS = new String[256];
+
+    static {
+        for (int i = 0; i < 256; i++) {
+            String bin = Integer.toBinaryString(i);
+            // Left-pad to 8 digits with zeros
+            BIN_CONSTANTS[i] = "00000000".substring(bin.length()) + bin;
+        }
+    }
+
     /**
      * Very fast 8-bit int to ASCII conversion.
      *
@@ -116,4 +126,14 @@ public class Utils {
     public static int address(int lowByte, int hiByte) {
         return ((hiByte << 8) | lowByte) & 0xffff;
     }
+
+    /**
+     * Very fast 8-bit int to binary conversion, with zero-padded output.
+     *
+     * @param val The unsigned 8-bit value to convert to a zero padded binary string.
+     * @return Eight digit, zero padded binary string.
+     */
+    public static String byteToBin(int val) {
+        return BIN_CONSTANTS[val & 0xff];
+    }
 }