diff --git a/py_gen/templates/util.py b/py_gen/templates/util.py
index 397c184..c4de5a3 100644
--- a/py_gen/templates/util.py
+++ b/py_gen/templates/util.py
@@ -69,3 +69,76 @@
         if v == v2:
             return k
     return v
+
+def pack_port_no(value):
+:: if version == 1:
+    return struct.pack("!H", value)
+:: else:
+    return struct.pack("!L", value)
+:: #endif
+
+def unpack_port_no(reader):
+:: if version == 1:
+    return reader.read("!H")[0]
+:: else:
+    return reader.read("!L")[0]
+:: #endif
+
+def pack_fm_cmd(value):
+:: if version == 1:
+    return struct.pack("!H", value)
+:: else:
+    return struct.pack("!B", value)
+:: #endif
+
+def unpack_fm_cmd(reader):
+:: if version == 1:
+    return reader.read("!H")[0]
+:: else:
+    return reader.read("!B")[0]
+:: #endif
+
+def init_wc_bmap():
+:: if version <= 2:
+    return const.OFPFW_ALL
+:: else:
+    return 0
+:: #endif
+
+def pack_wc_bmap(value):
+:: if version <= 2:
+    return struct.pack("!L", value)
+:: else:
+    return struct.pack("!Q", value)
+:: #endif
+
+def unpack_wc_bmap(reader):
+:: if version <= 2:
+    return reader.read("!L")[0]
+:: else:
+    return reader.read("!Q")[0]
+:: #endif
+
+def init_match_bmap():
+:: if version <= 2:
+    return const.OFPFW_ALL
+:: else:
+    return 0
+:: #endif
+
+def pack_match_bmap(value):
+:: if version <= 2:
+    return struct.pack("!L", value)
+:: else:
+    return struct.pack("!Q", value)
+:: #endif
+
+def unpack_match_bmap(reader):
+:: if version <= 2:
+    return reader.read("!L")[0]
+:: else:
+    return reader.read("!Q")[0]
+:: #endif
+
+def pack_list(values):
+    return "".join([x.pack() for x in values])