DTX DL: use FSM for AMR

Use dedicated FSM to handle all DTX DL related events:
- add explicit checks if DTX DL is enabled (fixes regression for non-DTX
setup introduced in 654175f33bd412671e3ef8cdd65c0689d10f278c)
- fix handling of AMR CMI for SPEECH frames
- add FSM for DTX DL
- sync with corresponding changes in OpenBSC's
- handle FACCH-related DTX ONSET events

This affects both lc15 and sysmobts and requires corresponding change in
OpenBSC (Change-Id: Idac8609faf9b5ced818fde899ccfc6ed0c42e8fd).

Change-Id: I74a0b42cb34d525b8a70d264135e82994ca70d31

1 files changed, 35 insertions, 0 deletions

diff --git a/include/osmo-bts/dtx_dl_amr_fsm.h b/include/osmo-bts/dtx_dl_amr_fsm.h
new file mode 100644
index 00000000..8b195953
--- /dev/null
+++ b/include/osmo-bts/dtx_dl_amr_fsm.h
@@ -0,0 +1,35 @@
+#pragma once
+
+#include <osmocom/core/fsm.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/logging.h>
+
+/* DTX DL AMR FSM */
+
+#define X(s) (1 << (s))
+
+enum dtx_dl_amr_fsm_states {
+	ST_VOICE,
+	ST_SID_F1,
+	ST_SID_F2,
+	ST_F1_INH,
+	ST_U_INH,
+	ST_SID_U,
+	ST_ONSET_V,
+	ST_ONSET_F,
+	ST_FACCH_V,
+	ST_FACCH,
+};
+
+enum dtx_dl_amr_fsm_events {
+	E_VOICE,
+	E_ONSET,
+	E_FACCH,
+	E_COMPL,
+	E_INHIB,
+	E_SID_F,
+	E_SID_U,
+};
+
+extern const struct value_string dtx_dl_amr_fsm_event_names[];
+extern struct osmo_fsm dtx_dl_amr_fsm;