diff --git a/src/python/loxi/of12/action.py b/src/python/loxi/of12/action.py
index 5cfd754..72685a7 100644
--- a/src/python/loxi/of12/action.py
+++ b/src/python/loxi/of12/action.py
@@ -48,7 +48,7 @@
         obj.type = reader.read("!H")[0]
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -106,7 +106,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.experimenter = reader.read("!L")[0]
         obj.data = str(reader.read_all())
         return obj
@@ -165,7 +165,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
         obj.subtype = reader.read("!L")[0]
@@ -217,7 +217,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
         _subtype = reader.read("!L")[0]
@@ -283,7 +283,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
         _subtype = reader.read("!L")[0]
@@ -349,7 +349,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
         _subtype = reader.read("!L")[0]
@@ -396,7 +396,7 @@
         assert(_type == 12)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -436,7 +436,7 @@
         assert(_type == 11)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -476,7 +476,7 @@
         assert(_type == 16)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -516,7 +516,7 @@
         assert(_type == 24)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -560,7 +560,7 @@
         assert(_type == 22)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.group_id = reader.read("!L")[0]
         return obj
 
@@ -618,7 +618,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 8992)
         obj.subtype = reader.read("!H")[0]
@@ -668,7 +668,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 8992)
         _subtype = reader.read("!H")[0]
@@ -723,7 +723,7 @@
         assert(_type == 0)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.port = util.unpack_port_no(reader)
         obj.max_len = reader.read("!H")[0]
         reader.skip(6)
@@ -777,7 +777,7 @@
         assert(_type == 20)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.ethertype = reader.read("!H")[0]
         reader.skip(2)
         return obj
@@ -821,7 +821,7 @@
         assert(_type == 18)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -866,7 +866,7 @@
         assert(_type == 19)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.ethertype = reader.read("!H")[0]
         reader.skip(2)
         return obj
@@ -915,7 +915,7 @@
         assert(_type == 17)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.ethertype = reader.read("!H")[0]
         reader.skip(2)
         return obj
@@ -965,7 +965,7 @@
         assert(_type == 25)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.field = oxm.oxm.unpack(reader)
         return obj
 
@@ -1013,7 +1013,7 @@
         assert(_type == 15)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.mpls_ttl = reader.read("!B")[0]
         reader.skip(3)
         return obj
@@ -1062,7 +1062,7 @@
         assert(_type == 23)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.nw_ttl = reader.read("!B")[0]
         reader.skip(3)
         return obj
@@ -1110,7 +1110,7 @@
         assert(_type == 21)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.queue_id = reader.read("!L")[0]
         return obj
 
diff --git a/src/python/loxi/of12/common.py b/src/python/loxi/of12/common.py
index 4bb1449..b091544 100644
--- a/src/python/loxi/of12/common.py
+++ b/src/python/loxi/of12/common.py
@@ -115,7 +115,7 @@
         obj.type = reader.read("!H")[0]
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         return obj
 
     def __eq__(self, other):
@@ -214,7 +214,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.flags = reader.read("!L")[0]
         obj.port_no = util.unpack_port_no(reader)
         obj.loopback_port_no = util.unpack_port_no(reader)
@@ -342,7 +342,7 @@
         assert(_type == 0)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.port_no = reader.read("!L")[0]
         obj.ingress_tpid = reader.read("!H")[0]
         obj.ingress_vlan_id = reader.read("!H")[0]
@@ -426,7 +426,7 @@
         obj = bucket()
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (0 + 2))
+        reader = orig_reader.slice(_len, 2)
         obj.weight = reader.read("!H")[0]
         obj.watch_port = util.unpack_port_no(reader)
         obj.watch_group = reader.read("!L")[0]
@@ -582,7 +582,7 @@
         obj = flow_stats_entry()
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (0 + 2))
+        reader = orig_reader.slice(_length, 2)
         obj.table_id = reader.read("!B")[0]
         reader.skip(1)
         obj.duration_sec = reader.read("!L")[0]
@@ -687,7 +687,7 @@
         obj = group_desc_stats_entry()
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (0 + 2))
+        reader = orig_reader.slice(_length, 2)
         obj.group_type = reader.read("!B")[0]
         reader.skip(1)
         obj.group_id = reader.read("!L")[0]
@@ -762,7 +762,7 @@
         obj = group_stats_entry()
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (0 + 2))
+        reader = orig_reader.slice(_length, 2)
         reader.skip(2)
         obj.group_id = reader.read("!L")[0]
         obj.ref_count = reader.read("!L")[0]
@@ -831,7 +831,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.oxm_list = loxi.generic_util.unpack_list(reader, oxm.oxm.unpack)
         orig_reader.skip_align()
         return obj
@@ -887,7 +887,7 @@
         obj.port = util.unpack_port_no(reader)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (8 + 2))
+        reader = orig_reader.slice(_len, 10)
         reader.skip(6)
         obj.properties = loxi.generic_util.unpack_list(reader, common.queue_prop.unpack)
         return obj
@@ -1245,7 +1245,7 @@
         obj.type = reader.read("!H")[0]
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -1303,7 +1303,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.experimenter = reader.read("!L")[0]
         reader.skip(4)
@@ -1356,7 +1356,7 @@
         assert(_type == 2)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.rate = reader.read("!H")[0]
         reader.skip(6)
@@ -1407,7 +1407,7 @@
         assert(_type == 1)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.rate = reader.read("!H")[0]
         reader.skip(6)
diff --git a/src/python/loxi/of12/instruction.py b/src/python/loxi/of12/instruction.py
index 06786ed..915035d 100644
--- a/src/python/loxi/of12/instruction.py
+++ b/src/python/loxi/of12/instruction.py
@@ -48,7 +48,7 @@
         obj.type = reader.read("!H")[0]
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -93,7 +93,7 @@
         assert(_type == 4)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.actions = loxi.generic_util.unpack_list(reader, action.action.unpack)
         return obj
@@ -137,7 +137,7 @@
         assert(_type == 5)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         return obj
 
@@ -193,7 +193,7 @@
         assert(_type == 65535)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.experimenter = reader.read("!L")[0]
         obj.data = str(reader.read_all())
         return obj
@@ -243,7 +243,7 @@
         assert(_type == 1)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         obj.table_id = reader.read("!B")[0]
         reader.skip(3)
         return obj
@@ -292,7 +292,7 @@
         assert(_type == 3)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.actions = loxi.generic_util.unpack_list(reader, action.action.unpack)
         return obj
@@ -346,7 +346,7 @@
         assert(_type == 2)
         _len = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_len - (2 + 2))
+        reader = orig_reader.slice(_len, 4)
         reader.skip(4)
         obj.metadata = reader.read("!Q")[0]
         obj.metadata_mask = reader.read("!Q")[0]
diff --git a/src/python/loxi/of12/message.py b/src/python/loxi/of12/message.py
index ab8f30b..e61b6da 100644
--- a/src/python/loxi/of12/message.py
+++ b/src/python/loxi/of12/message.py
@@ -56,7 +56,7 @@
         obj.type = reader.read("!B")[0]
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         return obj
 
@@ -128,7 +128,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.stats_type = reader.read("!H")[0]
         obj.flags = reader.read("!H")[0]
@@ -214,7 +214,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 2)
@@ -310,7 +310,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.stats_type = reader.read("!H")[0]
         obj.flags = reader.read("!H")[0]
@@ -412,7 +412,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 2)
@@ -518,7 +518,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.err_type = reader.read("!H")[0]
         return obj
@@ -586,7 +586,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 2)
@@ -664,7 +664,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 3)
@@ -742,7 +742,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 4)
@@ -820,7 +820,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 1)
@@ -886,7 +886,7 @@
         assert(_type == 21)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         return obj
 
@@ -940,7 +940,7 @@
         assert(_type == 20)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         return obj
 
@@ -1016,7 +1016,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.experimenter = reader.read("!L")[0]
         obj.subtype = reader.read("!L")[0]
@@ -1096,7 +1096,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1163,7 +1163,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1230,7 +1230,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1297,7 +1297,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1364,7 +1364,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1436,7 +1436,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1513,7 +1513,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1585,7 +1585,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1652,7 +1652,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1720,7 +1720,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1794,7 +1794,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1877,7 +1877,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -1975,7 +1975,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -2068,7 +2068,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -2155,7 +2155,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -2253,7 +2253,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -2342,7 +2342,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -2415,7 +2415,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -2508,7 +2508,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -2622,7 +2622,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 65535)
@@ -2718,7 +2718,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 65535)
@@ -2814,7 +2814,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 65535)
@@ -2910,7 +2910,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 65535)
@@ -2990,7 +2990,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -3067,7 +3067,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -3139,7 +3139,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -3211,7 +3211,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 6035143)
@@ -3307,7 +3307,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 0)
@@ -3402,7 +3402,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 0)
@@ -3469,7 +3469,7 @@
         assert(_type == 3)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.data = str(reader.read_all())
         return obj
@@ -3533,7 +3533,7 @@
         assert(_type == 2)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.data = str(reader.read_all())
         return obj
@@ -3609,7 +3609,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 65535)
@@ -3711,7 +3711,7 @@
         assert(_type == 6)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.datapath_id = reader.read("!Q")[0]
         obj.n_buffers = reader.read("!L")[0]
@@ -3796,7 +3796,7 @@
         assert(_type == 5)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         return obj
 
@@ -3923,7 +3923,7 @@
         assert(_type == 14)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.cookie = reader.read("!Q")[0]
         obj.cookie_mask = reader.read("!Q")[0]
@@ -4103,7 +4103,7 @@
         assert(_type == 14)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.cookie = reader.read("!Q")[0]
         obj.cookie_mask = reader.read("!Q")[0]
@@ -4283,7 +4283,7 @@
         assert(_type == 14)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.cookie = reader.read("!Q")[0]
         obj.cookie_mask = reader.read("!Q")[0]
@@ -4463,7 +4463,7 @@
         assert(_type == 14)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.cookie = reader.read("!Q")[0]
         obj.cookie_mask = reader.read("!Q")[0]
@@ -4592,7 +4592,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 5)
@@ -4721,7 +4721,7 @@
         assert(_type == 14)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.cookie = reader.read("!Q")[0]
         obj.cookie_mask = reader.read("!Q")[0]
@@ -4901,7 +4901,7 @@
         assert(_type == 14)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.cookie = reader.read("!Q")[0]
         obj.cookie_mask = reader.read("!Q")[0]
@@ -5073,7 +5073,7 @@
         assert(_type == 11)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.cookie = reader.read("!Q")[0]
         obj.priority = reader.read("!H")[0]
@@ -5195,7 +5195,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 1)
@@ -5302,7 +5302,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 1)
@@ -5406,7 +5406,7 @@
         assert(_type == 8)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.flags = reader.read("!H")[0]
         obj.miss_send_len = reader.read("!H")[0]
@@ -5470,7 +5470,7 @@
         assert(_type == 7)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         return obj
 
@@ -5552,7 +5552,7 @@
         assert(_type == 15)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.command = reader.read("!H")[0]
         obj.group_type = reader.read("!B")[0]
@@ -5642,7 +5642,7 @@
         assert(_type == 15)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _command = reader.read("!H")[0]
         assert(_command == 0)
@@ -5732,7 +5732,7 @@
         assert(_type == 15)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _command = reader.read("!H")[0]
         assert(_command == 2)
@@ -5817,7 +5817,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 7)
@@ -5892,7 +5892,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 7)
@@ -6012,7 +6012,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 8)
@@ -6132,7 +6132,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 8)
@@ -6206,7 +6206,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 6)
@@ -6290,7 +6290,7 @@
         assert(_type == 15)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _command = reader.read("!H")[0]
         assert(_command == 1)
@@ -6375,7 +6375,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 6)
@@ -6456,7 +6456,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 6)
@@ -6524,7 +6524,7 @@
         assert(_type == 0)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         return obj
 
@@ -6590,7 +6590,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 0)
@@ -6670,7 +6670,7 @@
         assert(_type == 4)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _experimenter = reader.read("!L")[0]
         assert(_experimenter == 8992)
@@ -6759,7 +6759,7 @@
         assert(_type == 10)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.buffer_id = reader.read("!L")[0]
         obj.total_len = reader.read("!H")[0]
@@ -6867,7 +6867,7 @@
         assert(_type == 13)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.buffer_id = reader.read("!L")[0]
         obj.in_port = util.unpack_port_no(reader)
@@ -6971,7 +6971,7 @@
         assert(_type == 16)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.port_no = util.unpack_port_no(reader)
         reader.skip(4)
@@ -7065,7 +7065,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 7)
@@ -7144,7 +7144,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 4)
@@ -7225,7 +7225,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 4)
@@ -7304,7 +7304,7 @@
         assert(_type == 12)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.reason = reader.read("!B")[0]
         reader.skip(7)
@@ -7380,7 +7380,7 @@
         assert(_type == 23)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.port = util.unpack_port_no(reader)
         reader.skip(4)
@@ -7451,7 +7451,7 @@
         assert(_type == 22)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.port = util.unpack_port_no(reader)
         reader.skip(4)
@@ -7523,7 +7523,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 9)
@@ -7602,7 +7602,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 5)
@@ -7687,7 +7687,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 5)
@@ -7770,7 +7770,7 @@
         assert(_type == 25)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.role = reader.read("!L")[0]
         reader.skip(4)
@@ -7846,7 +7846,7 @@
         assert(_type == 24)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.role = reader.read("!L")[0]
         reader.skip(4)
@@ -7923,7 +7923,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 11)
@@ -7999,7 +7999,7 @@
         assert(_type == 9)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.flags = reader.read("!H")[0]
         obj.miss_send_len = reader.read("!H")[0]
@@ -8075,7 +8075,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 10)
@@ -8152,7 +8152,7 @@
         assert(_type == 17)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         obj.table_id = reader.read("!B")[0]
         reader.skip(3)
@@ -8229,7 +8229,7 @@
         assert(_type == 1)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _err_type = reader.read("!H")[0]
         assert(_err_type == 8)
@@ -8308,7 +8308,7 @@
         assert(_type == 19)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 3)
@@ -8383,7 +8383,7 @@
         assert(_type == 18)
         _length = reader.read("!H")[0]
         orig_reader = reader
-        reader = orig_reader.slice(_length - (2 + 2))
+        reader = orig_reader.slice(_length, 4)
         obj.xid = reader.read("!L")[0]
         _stats_type = reader.read("!H")[0]
         assert(_stats_type == 3)