make sure ta is signed before operating

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@16251 f5534014-38df-0310-8fa8-9805f1628bb7

diff --git a/epan/dissectors/packet-iuup.c b/epan/dissectors/packet-iuup.c
index 97d86a7a6593673b9170cb59cec02527cf73776d..8194e23f0bf9c6690e4ddba2712f1326975b98f8 100644 (file)
--- a/epan/dissectors/packet-iuup.c
+++ b/epan/dissectors/packet-iuup.c
@@ -662,7 +662,7 @@ static void dissect_iuup(tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree) {
                     } else if (ta >= 129 && ta <= 208) {
                         pi = proto_tree_add_uint(time_tree,hf_iuup_advance,tvb,4,1,(ta-128) * 500);
                         PROTO_ITEM_SET_GENERATED(pi);
-                        pi = proto_tree_add_float(time_tree,hf_iuup_delta,tvb,4,1,((gfloat)((gint)(-((gint)(ta-128))) * 500))/1000000.0);
+                        pi = proto_tree_add_float(time_tree,hf_iuup_delta,tvb,4,1,((gfloat)((gint)(-(((gint)ta)-128))) * 500)/1000000.0);
                         PROTO_ITEM_SET_GENERATED(pi);
                     } else {
                         proto_item_set_expert_flags(pi, PI_MALFORMED, PI_ERROR);