diff --git a/common/hw-sub_regs.ads b/common/hw-sub_regs.ads
new file mode 100644
index 0000000..ca04c1d
--- /dev/null
+++ b/common/hw-sub_regs.ads
@@ -0,0 +1,26 @@
+--
+-- Copyright (C) 2016 secunet Security Networks AG
+--
+-- 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; version 2 of the License.
+--
+-- 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.
+--
+
+generic
+   type Index_T is (<>);
+package HW.Sub_Regs is
+
+   type T is record
+      Byte_Offset : Natural;
+      MSB    : Natural;
+      LSB   : Natural;
+   end record;
+
+   type Array_T is array (Index_T) of T;
+
+end HW.Sub_Regs;