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, 320 insertions, 0 deletions

diff --git a/src/common/dtx_dl_amr_fsm.c b/src/common/dtx_dl_amr_fsm.c
new file mode 100644
index 00000000..b110cf21
--- /dev/null
+++ b/src/common/dtx_dl_amr_fsm.c
@@ -0,0 +1,320 @@
+/* DTX DL AMR FSM */
+
+/* (C) 2016 by sysmocom s.f.m.c. GmbH
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmo-bts/dtx_dl_amr_fsm.h>
+#include <osmo-bts/logging.h>
+
+void dtx_fsm_voice(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_VOICE:
+	case E_FACCH:
+		break;
+	case E_SID_F:
+	case E_SID_U:
+		osmo_fsm_inst_state_chg(fi, ST_SID_F1, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Inexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_sid_f1(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_SID_F:
+/* FIXME: what shall we do if we get SID-FIRST _again_ (twice in a row)?
+   Was observed during testing, let's just ignore it for now */
+		break;
+	case E_SID_U:
+		osmo_fsm_inst_state_chg(fi, ST_SID_U, 0, 0);
+		break;
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_VOICE, 0, 0);
+		break;
+	case E_FACCH:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_F, 0, 0);
+		break;
+	case E_COMPL:
+		osmo_fsm_inst_state_chg(fi, ST_SID_F2, 0, 0);
+		break;
+	case E_INHIB:
+		osmo_fsm_inst_state_chg(fi, ST_F1_INH, 0, 0);
+		break;
+	case E_ONSET:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_V, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_sid_f2(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_SID_U:
+		osmo_fsm_inst_state_chg(fi, ST_SID_U, 0, 0);
+		break;
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_VOICE, 0, 0);
+		break;
+	case E_FACCH:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_F, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_f1_inh(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_V, 0, 0);
+		break;
+	case E_FACCH:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_F, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_u_inh(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_V, 0, 0);
+		break;
+	case E_FACCH:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_F, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_sid_upd(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_FACCH:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_F, 0, 0);
+		break;
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_VOICE, 0, 0);
+		break;
+	case E_INHIB:
+		osmo_fsm_inst_state_chg(fi, ST_U_INH, 0, 0);
+		break;
+	case E_SID_U:
+	case E_SID_F:
+/* FIXME: what shall we do if we get SID-FIRST _after_ sending SID-UPDATE?
+   Was observed during testing, let's just ignore it for now */
+		break;
+	case E_ONSET:
+		osmo_fsm_inst_state_chg(fi, ST_ONSET_V, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_onset_v(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_SID_U:
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_VOICE, 0, 0);
+		break;
+	case E_FACCH:
+		osmo_fsm_inst_state_chg(fi, ST_FACCH_V, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_onset_f(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_SID_U:
+		break;
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_VOICE, 0, 0);
+		break;
+	case E_FACCH:
+		osmo_fsm_inst_state_chg(fi, ST_FACCH, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_facch_v(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_FACCH:
+		break;
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_VOICE, 0, 0);
+		break;
+	case E_SID_U:
+		break;
+	case E_SID_F:
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+void dtx_fsm_facch(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case E_FACCH:
+		break;
+	case E_VOICE:
+		osmo_fsm_inst_state_chg(fi, ST_VOICE, 0, 0);
+		break;
+	case E_SID_U:
+	case E_SID_F:
+		osmo_fsm_inst_state_chg(fi, ST_SID_F1, 0, 0);
+		break;
+	default:
+		LOGP(DL1P, LOGL_ERROR, "Unexpected event %d\n", event);
+		OSMO_ASSERT(0);
+		break;
+	}
+}
+
+static struct osmo_fsm_state dtx_dl_amr_fsm_states[] = {
+	/* default state for non-DTX and DTX when SPEECH is in progress */
+	[ST_VOICE] = {
+		.in_event_mask = X(E_SID_F) | X(E_SID_U) | X(E_VOICE) | X(E_FACCH),
+		.out_state_mask = X(ST_SID_F1),
+		.name = "Voice",
+		.action = dtx_fsm_voice,
+	},
+	/* SID-FIRST or SID-FIRST-P1 in case of AMR HR:
+	   start of silence period (might be interrupted in case of AMR HR) */
+	[ST_SID_F1]= {
+		.in_event_mask = X(E_SID_F) | X(E_SID_U) | X(E_VOICE) | X(E_FACCH) | X(E_COMPL) | X(E_INHIB) | X(E_ONSET),
+		.out_state_mask = X(ST_SID_U) | X(ST_VOICE) | X(ST_ONSET_F) | X(ST_SID_F2) | X(ST_F1_INH) | X(ST_ONSET_V),
+		.name = "SID-FIRST (P1)",
+		.action = dtx_fsm_sid_f1,
+	},
+	/* SID-FIRST P2 (only for AMR HR):
+	   actual start of silence period in case of AMR HR*/
+	[ST_SID_F2]= {
+		.in_event_mask = X(E_SID_U) | X(E_VOICE) | X(E_FACCH),
+		.out_state_mask = X(ST_SID_U) | X(ST_VOICE) | X(ST_ONSET_F),
+		.name = "SID-FIRST (P2)",
+		.action = dtx_fsm_sid_f2,
+	},
+	/* SID-FIRST Inhibited:
+	   incoming SPEECH or FACCH (only for AMR HR) */
+	[ST_F1_INH]= {
+		.in_event_mask = X(E_VOICE) | X(E_FACCH),
+		.out_state_mask = X(ST_VOICE) | X(ST_FACCH_V),
+		.name = "SID-FIRST (Inh)",
+		.action = dtx_fsm_f1_inh,
+	},
+	/* SID-UPDATE Inhibited:
+	   incoming SPEECH or FACCH (only for AMR HR) */
+	[ST_U_INH]= {
+		.in_event_mask = X(E_VOICE) | X(E_FACCH),
+		.out_state_mask = X(ST_VOICE) | X(ST_FACCH_V),
+		.name = "SID-UPDATE (Inh)",
+		.action = dtx_fsm_u_inh,
+	},
+	/* Silence period with periodic comfort noise data updates */
+	[ST_SID_U]= {
+		.in_event_mask = X(E_FACCH) | X(E_VOICE) | X(E_INHIB) | X(E_SID_U) | X(E_SID_F) | X(E_ONSET),
+		.out_state_mask = X(ST_ONSET_F) | X(ST_VOICE) | X(ST_U_INH) | X(ST_SID_U) | X(ST_ONSET_V),
+		.name = "SID-UPDATE",
+		.action = dtx_fsm_sid_upd,
+	},
+	/* ONSET - end of silent period due to incoming SPEECH frame */
+	[ST_ONSET_V]= {
+		.in_event_mask = X(E_VOICE) | X(E_FACCH),
+		.out_state_mask = X(ST_VOICE) | X(ST_FACCH_V),
+		.name = "ONSET (SPEECH)",
+		.action = dtx_fsm_onset_v,
+	},
+	/* ONSET - end of silent period due to incoming FACCH frame */
+	[ST_ONSET_F]= {
+		.in_event_mask = X(E_VOICE) | X(E_FACCH) | X(E_SID_U),
+		.out_state_mask = X(ST_VOICE) | X(ST_FACCH),
+		.name = "ONSET (FACCH)",
+		.action = dtx_fsm_onset_f,
+	},
+	/* FACCH sending state: SPEECH was observed before so once we're done
+	   FSM should get back to VOICE state */
+	[ST_FACCH_V]= {
+		.in_event_mask = X(E_FACCH) | X(E_VOICE) | X(E_SID_U) | X(E_SID_F),
+		.out_state_mask = X(ST_FACCH_V) | X(ST_VOICE) | X(ST_SID_F1),
+		.name = "FACCH (SPEECH)",
+		.action = dtx_fsm_facch_v,
+	},
+	/* FACCH sending state: no SPEECH was observed before so once we're done
+	   FSM should get back to silent period via SID-FIRST */
+	[ST_FACCH]= {
+		.in_event_mask = X(E_FACCH) | X(E_VOICE) | X(E_SID_U) | X(E_SID_F),
+		.out_state_mask = X(ST_FACCH_V) | X(ST_VOICE) | X(ST_SID_F1),
+		.name = "FACCH",
+		.action = dtx_fsm_facch,
+	},
+};
+
+const struct value_string dtx_dl_amr_fsm_event_names[] = {
+	{ E_VOICE,	"Voice" },
+	{ E_FACCH,	"FACCH" },
+	{ E_COMPL,	"Complete P1 -> P2" },
+	{ E_INHIB,	"Inhibit" },
+	{ E_SID_F,	"SID-FIRST" },
+	{ E_SID_U,	"SID-UPDATE" },
+	{ 0, 		NULL }
+};
+
+struct osmo_fsm dtx_dl_amr_fsm = {
+	.name = "DTX DL AMR FSM",
+	.states = dtx_dl_amr_fsm_states,
+	.num_states = ARRAY_SIZE(dtx_dl_amr_fsm_states),
+	.event_names = dtx_dl_amr_fsm_event_names,
+	.log_subsys = DL1C,
+};