Add gsmtap utility functions to libosmocore
This is imported from OsmocomBB/Layer23
diff --git a/include/osmocore/gsmtap_util.h b/include/osmocore/gsmtap_util.h
new file mode 100644
index 0000000..30fc126
--- /dev/null
+++ b/include/osmocore/gsmtap_util.h
@@ -0,0 +1,16 @@
+#ifndef _GSMTAP_UTIL_H
+#define _GSMTAP_UTIL_H
+
+#include <stdint.h>
+
+/* convert RSL channel number to GSMTAP channel type */
+uint8_t chantype_rsl2gsmtap(uint8_t rsl_chantype, uint8_t rsl_link_id);
+
+/* receive a message from L1/L2 and put it in GSMTAP */
+int gsmtap_sendmsg(uint16_t arfcn, uint8_t ts, uint8_t chan_type, uint8_t ss,
+ uint32_t fn, int8_t signal_dbm, uint8_t snr,
+ const uint8_t *data, unsigned int len);
+
+int gsmtap_init(uint32_t dst_ip);
+
+#endif /* _GSMTAP_UTIL_H */