add comments to describe functions

Change-Id: Ie351632001abbeb82008a5eecae0d0323a8ef7d7
Reviewed-on: https://gerrit.osmocom.org/106
Reviewed-by: Harald Welte <laforge@gnumonks.org>
Tested-by: Jenkins Builder
diff --git a/src/bts.cpp b/src/bts.cpp
index 03b0401..953ac4d 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -1317,6 +1317,7 @@
 	return -EINVAL;
 }
 
+/*! \brief process egprs and gprs data blocks */
 int gprs_rlcmac_pdch::rcv_data_block(uint8_t *data, uint32_t fn,
 	struct pcu_l1_meas *meas, GprsCodingScheme cs)
 {