better empty file handling

src/com/bytezone/diskbrowser/pascal/CatalogEntry.java

@@ -60,8 +60,7 @@ abstract class CatalogEntry implements AppleFileSource
   public List<DiskAddress> getSectors ()
   // ---------------------------------------------------------------------------------//
   {
-    List<DiskAddress> sectors = new ArrayList<> (blocks);
+    return new ArrayList<> (blocks);       // make a copy
-    return sectors;
   }
 
   // ---------------------------------------------------------------------------------//

src/com/bytezone/diskbrowser/pascal/FileEntry.java

@@ -61,16 +61,19 @@ public class FileEntry extends CatalogEntry
   public AbstractFile getDataSource ()
   // ---------------------------------------------------------------------------------//
   {
-    if (file != null)
+    if (file != null)       // previously built
       return file;
 
-    byte[] buffer = getExactBuffer ();
+    // check for empty file (e.g. see DC16.dsk)
-    if (buffer.length == 0)
+    if (firstBlock == lastBlock)
     {
-      file = new AssemblerProgram (name, buffer, 0);    // see DC16.dsk
+      file = new DefaultAppleFile (name, new byte[0]);
+      node.setAllowsChildren (false);
       return file;
     }
 
+    byte[] buffer = getExactBuffer ();
+
     switch (fileType)
     {
       case 2:                                         // code (6502 or Pascal)

src/com/bytezone/diskbrowser/pascal/PascalDisk.java

@@ -22,6 +22,7 @@ import com.bytezone.diskbrowser.utilities.HexFormatter;
 import com.bytezone.diskbrowser.utilities.Utility;
 import com.bytezone.diskbrowser.wizardry.Relocator;
 
+// useful : http://pascal.hansotten.com/ucsd-p-system/apple-pascal/apple-ii/
 // -----------------------------------------------------------------------------------//
 public class PascalDisk extends AbstractFormattedDisk
 // -----------------------------------------------------------------------------------//