tree cf9f5052348eae7207bceeb9803967686ca3e692
parent 26d0fe3c89042ed4008903dbe12c5110d8f9fc48
author Holger Hans Peter Freyther <zecke@selfish.org> 1308866007 -0400
committer Holger Hans Peter Freyther <zecke@selfish.org> 1325872325 +0100

gprs: Honor GSM 04.64 8.4.2 Receipt of unacknowledged information

GSM 04.64 8.4.2 asks to ignore UI frames if the DLCI is not known,
or if the "(V(UR)- 32) <= N(U) < V(UR)". E.g. if we want to have
V(UR) == 511 and this frame is dropped, we would ignore N(U)'s
0 to 510. Calculate the delta.

The code is based on Jonathan Santos's "LLC UI window" fix but the
issue was discovered independly.