include/osmocom/gsm: add rtp_extensions.h

Previous patches add definitions of GSM0808_IE_THEMWI_RTP_EXTENSIONS
and RSL_IE_OSMO_RTP_EXTENSIONS to BSSMAP and RSL; this new header file
provides definitions for individual bits in the single value octet
of the new IE.

Related: OS#6448
Change-Id: I0eccfe5ddcf44f8f20440acb01e2d4870ec0cd91
---
M include/osmocom/gsm/Makefile.am
A include/osmocom/gsm/rtp_extensions.h
2 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/include/osmocom/gsm/Makefile.am b/include/osmocom/gsm/Makefile.am
index 5678a51..e42ffec 100644
--- a/include/osmocom/gsm/Makefile.am
+++ b/include/osmocom/gsm/Makefile.am
@@ -50,6 +50,7 @@
 	oap_client.h \
 	rlp.h \
 	rsl.h \
+	rtp_extensions.h \
 	rxlev_stat.h \
 	sysinfo.h \
 	tlv.h \
diff --git a/include/osmocom/gsm/rtp_extensions.h b/include/osmocom/gsm/rtp_extensions.h
new file mode 100644
index 0000000..edea431
--- /dev/null
+++ b/include/osmocom/gsm/rtp_extensions.h
@@ -0,0 +1,23 @@
+/*
+ * Themyscira Wireless Technical Specification TW-TS-003 defines a BSSMAP
+ * extension whereby a CN implementation and a BSS implementation can
+ * negotiate the use of non-3GPP-standard extensions to RTP user plane,
+ * extensions that modify RTP formats counter to the stipulations of
+ * 3GPP TS 48.103.  There is also a private Osmocom-defined IE in Abis RSL
+ * that communicates the same RTP extensions from OsmoBSC to OsmoBTS.
+ *
+ * This header file defines the meaning of the bits in the first (and currently
+ * only) value octet of the TLV IE added to BSSMAP and RSL interfaces,
+ * namely, GSM0808_IE_THEMWI_RTP_EXTENSIONS and RSL_IE_OSMO_RTP_EXTENSIONS.
+ * It is based on this authoritative definition:
+ *
+ * https://www.freecalypso.org/specs/tw-ts-003-v010002.txt
+ *
+ * Section 5.3 in the above specification defines the assignment of
+ * individual bits in the single value octet.
+ */
+
+#pragma once
+
+#define	OSMO_RTP_EXT_TWTS001	0x01
+#define	OSMO_RTP_EXT_TWTS002	0x02

