Review

15

sos/smartcards/BERTLVObject.java

readTag(DataInputStream)

class BERTLVObject {
   private void readTag(DataInputStream in) throws IOException {
      int b = in.readUnsignedByte();
      if (b == 0x00000000 || b == 0x000000FF) {
         throw new IllegalArgumentException("00 or FF tag not allowed");
      }
      switch (b & 0x000000C0) {
         case 0x00000000: tagClass = UNIVERSAL_CLASS; break;
         case 0x00000040: tagClass = APPLICATION_CLASS; break;
         case 0x00000080: tagClass = CONTEXT_SPECIFIC_CLASS; break;
         case 0x000000C0: tagClass = PRIVATE_CLASS; break;
      }
      switch (b & 0x00000020) {
         case 0x00000000: isPrimitive = true; break;
         case 0x00000020: isPrimitive = false; break;
      }
      switch (b & 0x0000001F) {
         case 0x0000001F:
            ArrayList tagBytes = new ArrayList();
            tagBytes.add(new Integer(b));
            b = in.readUnsignedByte();
            while ((b & 0x00000080) == 0x00000080) {
               tagBytes.add(new Integer(b));
            }
            tagBytes.add(new Integer(b));
            tag = new byte[tagBytes.size()];
            for (int i = 0; i < tagBytes.size(); i++) {
               tag[i] = (byte)(((Integer)tagBytes.get(i)).intValue());
            }
            break;
         default:
            tag = new byte[1]; tag[0] = (byte)b; break;
      }
      if (tag == null) {
         throw new NumberFormatException("Could not read tag");
      }
   }

}