diff --git a/common/hw-pci.ads b/common/hw-pci.ads
new file mode 100644
index 0000000..da4f42f
--- /dev/null
+++ b/common/hw-pci.ads
@@ -0,0 +1,61 @@
+--
+-- Copyright (C) 2017 Nico Huber <nico.h@gmx.de>
+--
+-- 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.
+--
+
+package HW.PCI
+is
+
+   type Bus is range 0 .. 255;
+   type Slot is range 0 .. 31;
+   type Func is range 0 ..  7;
+
+   type Address is record
+      Bus   : PCI.Bus;
+      Slot  : PCI.Slot;
+      Func  : PCI.Func;
+   end record;
+
+   type Index is range 0 .. 4095;
+
+   Vendor_Id                     : constant Index := 16#00#;
+   Device_Id                     : constant Index := 16#02#;
+   Command                       : constant Index := 16#04#;
+      Command_Memory             : constant := 16#02#;
+   Header_Type                   : constant Index := 16#0e#;
+      Header_Type_Mask           : constant := 16#7f#;
+      Header_Type_Normal         : constant := 16#00#;
+
+   type Resource is (Res0, Res1, Res2, Res3, Res4, Res5);
+   Base_Address : constant array (Resource) of Index :=
+     (16#10#, 16#14#, 16#18#, 16#1c#, 16#20#, 16#24#);
+      Base_Address_Space_Mask    : constant := 1 * 2 ** 0;
+      Base_Address_Space_IO      : constant := 1 * 2 ** 0;
+      Base_Address_Space_Mem     : constant := 0 * 2 ** 0;
+      Base_Address_Mem_Type_Mask : constant := 3 * 2 ** 1;
+      Base_Address_Mem_Type_32   : constant := 0 * 2 ** 1;
+      Base_Address_Mem_Type_1M   : constant := 1 * 2 ** 1;
+      Base_Address_Mem_Type_64   : constant := 2 * 2 ** 1;
+      Base_Address_Mem_Prefetch  : constant := 1 * 2 ** 3;
+      Base_Address_IO_Mask       : constant := 16#ffff_fffc#;
+      Base_Address_Mem_Mask      : constant := 16#ffff_fff0#;
+
+private
+   use type HW.Word64;
+   function Calc_Base_Address (Base_Addr : Word64; Dev : Address) return Word64
+   is
+     (Base_Addr +
+      Word64 (Dev.Bus) * 32 * 8 * 4096 +
+      Word64 (Dev.Slot) * 8 * 4096 +
+      Word64 (Dev.Func) * 4096);
+
+end HW.PCI;