Make udf_read_block more like 2 read. Implementation is closer

to the description (although it needs more work.)
udf_fs.h: break out udf_check_tag()
*.h: /*! -> /** - is more like Javadoc.

lib/udf/udf_fs.h

@@ -0,0 +1,39 @@
+/*
+    $Id: udf_fs.h,v 1.1 2006/04/11 05:47:58 rocky Exp $
+
+    Copyright (C) 2006 Rocky Bernstein <rockyb@users.sourceforge.net>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#ifndef __CDIO_UDF_FS_H__
+#define __CDIO_UDF_FS_H__
+
+/**
+ * Check the descriptor tag for both the correct id and correct checksum.
+ * Return zero if all is good, -1 if not.
+ */
+int udf_checktag(const udf_tag_t *p_tag, udf_Uint16_t tag_id);
+
+#endif /* __CDIO_UDF_FS_H__ */
+
+
+/* 
+ * Local variables:
+ *  c-file-style: "gnu"
+ *  tab-width: 8
+ *  indent-tabs-mode: nil
+ * End:
+ */