refactoring

src/com/bytezone/diskbrowser/disk/NibDisk.java

@@ -18,19 +18,31 @@ public class NibDisk
   // .nib files are 232,960 bytes
   // 6,656 bytes x 35 tracks (0x1A00)
 
+  // add 'nib' to TreeBuilder to allow nib files to be selected
+
   public NibDisk (File file)
   {
     this.file = file;
-    byte[] buffer = new byte[6656];
+    byte[] trackBuffer = new byte[6656];
     try
     {
-      byte[] diskBuffer = new byte[10];
       BufferedInputStream in = new BufferedInputStream (new FileInputStream (file));
 
+      byte[] test = { (byte) 0xD5, (byte) 0xAA, (byte) 0xB5 };
       for (int i = 0; i < 35; i++)
       {
-        in.read (buffer);
-        //        System.out.println (HexFormatter.format (buffer));
+        in.read (trackBuffer);
+        //        System.out.println (HexFormatter.format (trackBuffer));
+        int offset = 0;
+        while (true)
+        {
+          offset = nibbler.findBytes (trackBuffer, offset, test);
+          if (offset < 0)
+            break;
+          System.out.printf ("found at %04X%n", offset);
+          ++offset;
+        }
+        break;        // just examine the first track
       }
 
       in.close ();

src/com/bytezone/diskbrowser/disk/Nibblizer.java

@@ -2,9 +2,9 @@ package com.bytezone.diskbrowser.disk;
 
 public class Nibblizer
 {
-  private static byte[] addressPrologue = { (byte) 0xD5, (byte) 0xAA, (byte) 0x96 };
-  private static byte[] dataPrologue = { (byte) 0xD5, (byte) 0xAA, (byte) 0xAD };
-  private static byte[] epilogue = { (byte) 0xDE, (byte) 0xAA, (byte) 0xEB };
+  static byte[] addressPrologue = { (byte) 0xD5, (byte) 0xAA, (byte) 0x96 };
+  static byte[] dataPrologue = { (byte) 0xD5, (byte) 0xAA, (byte) 0xAD };
+  static byte[] epilogue = { (byte) 0xDE, (byte) 0xAA, (byte) 0xEB };
 
   private static byte[] writeTranslateTable =
       { (byte) 0x96, (byte) 0x97, (byte) 0x9A, (byte) 0x9B, (byte) 0x9D, (byte) 0x9E,
@@ -92,7 +92,7 @@ public class Nibblizer
 
   public Nibblizer ()
   {
-    if (false)
+    if (false)      // test with the Beneath Apple Prodos example
     {
       byte[] testBuffer = decode6and2 (encode6and2 (xor), 0);
 
@@ -104,24 +104,24 @@ public class Nibblizer
     }
   }
 
-  public AddressField getAddressField (byte[] buffer, int offset)
+  AddressField getAddressField (byte[] buffer, int offset)
   {
     return new AddressField (buffer, offset);
   }
 
-  public DataField getDataField (byte[] buffer, int offset)
+  DataField getDataField (byte[] buffer, int offset)
   {
     return new DataField (buffer, offset);
   }
 
-  int decode4and4 (byte[] buffer, int offset)
+  private int decode4and4 (byte[] buffer, int offset)
   {
     int odds = ((buffer[offset] & 0xFF) << 1) + 1;
     int evens = buffer[offset + 1] & 0xFF;
     return odds & evens;
   }
 
-  byte[] decode6and2 (byte[] buffer, int offset)
+  private byte[] decode6and2 (byte[] buffer, int offset)
   {
     for (int i = 0; i < decode1.length; i++)
     {
@@ -168,7 +168,7 @@ public class Nibblizer
     return decodedBuffer;
   }
 
-  byte[] encode6and2 (byte[] buffer)
+  private byte[] encode6and2 (byte[] buffer)
   {
     byte[] encodedBuffer = new byte[343];
 
@@ -210,6 +210,40 @@ public class Nibblizer
     return bits == 1 ? 2 : bits == 2 ? 1 : bits;
   }
 
+  int skipBytes (byte[] buffer, int offset, byte skipValue)
+  {
+    int count = 0;
+    while (offset < buffer.length && buffer[offset++] == skipValue)
+      ++count;
+    return count;
+  }
+
+  private String listBytes (byte[] buffer, int offset, int length)
+  {
+    StringBuilder text = new StringBuilder ();
+
+    int max = Math.min (length + offset, buffer.length);
+    while (offset < max)
+      text.append (String.format ("%02X ", buffer[offset++]));
+
+    return text.toString ();
+  }
+
+  int findBytes (byte[] buffer, int offset, byte[] valueBuffer)
+  {
+    int length = valueBuffer.length;
+    int ptr = offset + length;
+
+    while (ptr < buffer.length)
+    {
+      if (matchBytes (buffer, ptr - length, valueBuffer))
+        return ptr - length;
+      ++ptr;
+    }
+
+    return -1;
+  }
+
   private boolean matchBytes (byte[] buffer, int offset, byte[] valueBuffer)
   {
     for (int i = 0; i < valueBuffer.length; i++)
@@ -222,28 +256,6 @@ public class Nibblizer
     return true;
   }
 
-  int skipBytes (byte[] buffer, int offset, byte skipValue)
-  {
-    int count = 0;
-    while (offset < buffer.length && buffer[offset++] == skipValue)
-      ++count;
-    return count;
-  }
-
-  int listBytes (byte[] buffer, int offset, int length)
-  {
-    int count = 0;
-    for (int i = 0; i < length; i++)
-    {
-      if (offset >= buffer.length)
-        break;
-      System.out.printf ("%02X ", buffer[offset++]);
-      ++count;
-    }
-
-    return count;
-  }
-
   abstract class Field
   {
     protected boolean valid;
@@ -287,10 +299,7 @@ public class Nibblizer
         valid = true;
       }
       else
-      {
-        listBytes (buffer, offset, 14);
-        System.out.println ();
-      }
+        System.out.println (listBytes (buffer, offset, 14));
 
       length = 14;
     }
@@ -298,6 +307,8 @@ public class Nibblizer
 
   class DataField extends Field
   {
+    byte[] dataBuffer;
+
     public DataField (byte[] buffer, int offset)
     {
       super (buffer, offset);
@@ -305,18 +316,17 @@ public class Nibblizer
       if (matchBytes (buffer, offset, dataPrologue))
       {
         valid = true;
+        dataBuffer = decode6and2 (buffer, offset + 3);
         if (!matchBytes (buffer, offset + 346, epilogue))
         {
           System.out.print ("   bad data epilogue: ");
-          listBytes (buffer, offset + 346, 3);
-          System.out.println ();
+          System.out.println (listBytes (buffer, offset + 346, 3));
         }
       }
       else
       {
         System.out.print ("   bad data prologue: ");
-        listBytes (buffer, offset, 3);
-        System.out.println ();
+        System.out.println (listBytes (buffer, offset, 3));
       }
 
       length = 349;

src/com/bytezone/diskbrowser/disk/V2dDisk.java

@@ -37,14 +37,16 @@ public class V2dDisk
   private static int[][] interleave =
       { { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 },
         { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 } };
+
   private static final int DOS = 0;
   private static final int PRODOS = 1;
 
+  private static final int TRACK_LENGTH = 6304;
+
   private final Nibblizer nibbler = new Nibblizer ();
 
   final File file;
   final int tracks;
-  //  int actualTracks;
 
   final byte[] buffer = new byte[4096 * 35];
 
@@ -52,6 +54,7 @@ public class V2dDisk
   {
     this.file = file;
     int tracks = 0;
+
     try
     {
       byte[] diskBuffer = new byte[10];
@@ -65,21 +68,24 @@ public class V2dDisk
       assert diskLength + 8 == file.length ();
       assert "D5NI".equals (id);
 
+      byte[] trackHeader = new byte[4];
+      byte[] trackData = new byte[TRACK_LENGTH];
+
       for (int i = 0; i < tracks; i++)
       {
-        byte[] trackHeader = new byte[4];
         in.read (trackHeader);
         int trackNumber = HexFormatter.getShortBigEndian (trackHeader, 0);
         int trackLength = HexFormatter.getShortBigEndian (trackHeader, 2);    // 6304
 
+        assert trackLength == TRACK_LENGTH;
+
+        int dataRead = in.read (trackData);
+        assert dataRead == TRACK_LENGTH;
+
         int fullTrackNo = trackNumber / 4;
         int halfTrackNo = trackNumber % 4;
 
-        byte[] trackData = new byte[trackLength];
-        in.read (trackData);
-
-        // only process full tracks
-        if (halfTrackNo == 0)
+        if (halfTrackNo == 0)                               // only process full tracks
           processTrack (fullTrackNo, trackData, buffer);
         else
           System.out.printf ("%s skipping half track %02X / %02X%n", file.getName (),
@@ -115,23 +121,17 @@ public class V2dDisk
       if (!addressField.isValid ())
         return false;
 
+      assert addressField.track == trackNo;
+
       ptr += addressField.size ();
       ptr += nibbler.skipBytes (buffer, ptr, (byte) 0xFF);        // gap2
 
       DataField dataField = nibbler.getDataField (buffer, ptr);
       if (!dataField.isValid ())
-      {
-        System.out.printf ("skipping data %02X / %02X%n", addressField.track,
-            addressField.sector);
         return false;
-      }
-
-      //      System.out.printf ("decoding track %02X / %02X%n", addressField.track,
-      //          addressField.sector);
-      byte[] decodedBuffer = nibbler.decode6and2 (buffer, ptr + 3);
 
       int offset = addressField.track * 4096 + interleave[DOS][addressField.sector] * 256;
-      System.arraycopy (decodedBuffer, 0, diskBuffer, offset, 256);
+      System.arraycopy (dataField.dataBuffer, 0, diskBuffer, offset, 256);
 
       ptr += dataField.size ();
       ptr += nibbler.skipBytes (buffer, ptr, (byte) 0xFF);        // gap3

src/com/bytezone/diskbrowser/gui/TreeBuilder.java

@@ -26,7 +26,7 @@ public class TreeBuilder
   private static SimpleDateFormat sdf = new SimpleDateFormat ("dd MMM yyyy");
   private static final boolean FULL_TREE = false;
   private static final List<String> suffixes =
-      Arrays.asList ("po", "dsk", "do", "hdv", "2mg", "v2d", "d13", "sdk", "gz");
+      Arrays.asList ("po", "dsk", "do", "hdv", "2mg", "v2d", "nib", "d13", "sdk", "gz");
 
   FileComparator fc = new FileComparator ();
   JTree tree;