Change in osmo-bts[master]: osmo-bts-virtual: implement GSMTAP_CHANNEL_VOICE

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laforge gerrit-no-reply at lists.osmocom.org
Tue Mar 10 12:31:06 UTC 2020 

laforge has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bts/+/17377 )

Change subject: osmo-bts-virtual: implement GSMTAP_CHANNEL_VOICE
......................................................................

osmo-bts-virtual: implement GSMTAP_CHANNEL_VOICE

GSMTAP_CHANNEL_VOICE is the mechanism by which GSMTAP can [finally!]
be used to transport circuit-switched voice codec payload, and not
just signalling.

Original patch by Neels Hofmeyr, heavily extended by Harald Welte.

Depends: libosmocore.git I952044a17334f35712e087dc41781805000aebc1
Change-Id: I1cd9a251ce0b87181a0822d7940bbfc9f1428543
---
M src/osmo-bts-virtual/l1_if.c
M src/osmo-bts-virtual/scheduler_virtbts.c
2 files changed, 79 insertions(+), 12 deletions(-)

Approvals:
  Jenkins Builder: Verified
  pespin: Looks good to me, but someone else must approve
  laforge: Looks good to me, approved



diff --git a/src/osmo-bts-virtual/l1_if.c b/src/osmo-bts-virtual/l1_if.c
index ab2cb76..b6a3507 100644
--- a/src/osmo-bts-virtual/l1_if.c
+++ b/src/osmo-bts-virtual/l1_if.c
@@ -128,12 +128,7 @@
 		break;
 	case GSMTAP_CHANNEL_TCH_F:
 	case GSMTAP_CHANNEL_TCH_H:
-#if 0
-		/* TODO: handle voice messages */
-		if (!facch && ! tch_acch) {
-			osmo_prim_init(&l1sap.oph, SAP_GSM_PH, PRIM_TCH, PRIM_OP_INDICATION, msg);
-		}
-#endif
+		/* This is TCH signalling, for voice frames see GSMTAP_CHANNEL_VOICE */
 	case GSMTAP_CHANNEL_SDCCH4:
 	case GSMTAP_CHANNEL_SDCCH8:
 	case GSMTAP_CHANNEL_PACCH:
@@ -151,6 +146,19 @@
 		l1sap.u.data.pdch_presence_info = PRES_INFO_BOTH;
 		l1if_process_meas_res(pinst->trx, timeslot, fn, chan_nr, 0, 0, 0, 0);
 		break;
+	case GSMTAP_CHANNEL_VOICE_F:
+	case GSMTAP_CHANNEL_VOICE_H:
+		/* the first byte indicates the type of voice codec (gsmtap_um_voice_type) */
+		msg->l2h = msgb_pull(msg, 1);
+		osmo_prim_init(&l1sap.oph, SAP_GSM_PH, PRIM_TCH, PRIM_OP_INDICATION, msg);
+		l1sap.u.tch.chan_nr = chan_nr;
+		l1sap.u.tch.fn = fn;
+		l1sap.u.tch.rssi = 0; /* Radio Signal Strength Indicator. Best -> 0 */
+		l1sap.u.tch.ber10k = 0; /* Bit Error Rate in 0.01%. Best -> 0 */
+		l1sap.u.tch.ta_offs_256bits = 0; /* Burst time of arrival in quarter bits. Probably used for Timing Advance calc. Best -> 0 */
+		l1sap.u.tch.lqual_cb = 10 * signal_dbm; /* Link quality in centiBel = 10 * dB. */
+		l1if_process_meas_res(pinst->trx, timeslot, fn, chan_nr, 0, 0, 0, 0);
+		break;
 	case GSMTAP_CHANNEL_AGCH:
 	case GSMTAP_CHANNEL_PCH:
 	case GSMTAP_CHANNEL_BCCH:
diff --git a/src/osmo-bts-virtual/scheduler_virtbts.c b/src/osmo-bts-virtual/scheduler_virtbts.c
index 90288d1..72a6874 100644
--- a/src/osmo-bts-virtual/scheduler_virtbts.c
+++ b/src/osmo-bts-virtual/scheduler_virtbts.c
@@ -52,8 +52,8 @@
  * This will at first wrap the msg with a GSMTAP header and then write it to the declared multicast socket.
  * TODO: we might want to remove unused argument uint8_t tn
  */
-static void tx_to_virt_um(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
-			  enum trx_chan_type chan, struct msgb *msg)
+static void _tx_to_virt_um(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
+			   enum trx_chan_type chan, struct msgb *msg, bool is_voice_frame)
 {
 	const struct trx_chan_desc *chdesc = &trx_chan_desc[chan];
 	struct msgb *outmsg;			/* msg to send with gsmtap header prepended */
@@ -76,7 +76,7 @@
 	    l1sap_fn2ccch_block(fn) >= num_agch(l1t->trx, "PH-DATA-REQ"))
 		gsmtap_chantype = GSMTAP_CHANNEL_PCH;
 	else
-		gsmtap_chantype = chantype_rsl2gsmtap(rsl_chantype, chdesc->link_id); /* the logical channel type */
+		gsmtap_chantype = chantype_rsl2gsmtap2(rsl_chantype, chdesc->link_id, is_voice_frame); /* the logical channel type */
 
 #if MODULO_HYPERFRAME
 	/* Restart fn after every superframe (26 * 51 frames) to simulate hyperframe overflow each 6 seconds. */
@@ -105,6 +105,65 @@
 	msgb_free(msg);
 }
 
+static void tx_to_virt_um(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
+			  enum trx_chan_type chan, struct msgb *msg)
+{
+	_tx_to_virt_um(l1t, tn, fn, chan, msg, false);
+}
+
+
+static struct gsm_lchan *lchan_from_l1t(struct l1sched_trx *l1t, uint8_t tn, enum trx_chan_type chan)
+{
+	struct gsm_bts_trx_ts *ts;
+	uint8_t subslot = 0;
+
+	OSMO_ASSERT(l1t && l1t->trx);
+
+	if (chan == TRXC_TCHH_1)
+		subslot = 1;
+
+	ts = &l1t->trx->ts[tn];
+	return &ts->lchan[subslot];
+}
+
+/* Determine the gsmtap_um_voice_type of a gsm_lchan */
+static int get_um_voice_type(const struct gsm_lchan *lchan)
+{
+	switch (lchan->tch_mode) {
+	case GSM48_CMODE_SPEECH_V1:
+		if (lchan->type == GSM_LCHAN_TCH_H)
+			return GSMTAP_UM_VOICE_HR;
+		else
+			return GSMTAP_UM_VOICE_FR;
+	case GSM48_CMODE_SPEECH_EFR:
+		return GSMTAP_UM_VOICE_EFR;
+	case GSM48_CMODE_SPEECH_AMR:
+		return GSMTAP_UM_VOICE_AMR;
+	default:
+		return -1;
+	}
+}
+
+static void tx_to_virt_um_voice_frame(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
+				      enum trx_chan_type chan, struct msgb *msg)
+{
+	struct gsm_lchan *lchan = lchan_from_l1t(l1t, tn, chan);
+	int um_voice_type;
+
+	OSMO_ASSERT(lchan);
+	um_voice_type = get_um_voice_type(lchan);
+	if (um_voice_type < 0) {
+		LOGPLCHAN(lchan, DL1P, LOGL_ERROR, "Cannot determine Um voice type from lchan\n");
+		um_voice_type = 0xff;
+	}
+
+	/* the first byte indicates the type of voice codec (gsmtap_um_voice_type) */
+	msgb_pull_to_l2(msg);
+	msgb_push_u8(msg, um_voice_type);
+	msg->l2h = msg->data;
+	_tx_to_virt_um(l1t, tn, fn, chan, msg, true);
+}
+
 /*
  * TX on downlink
  */
@@ -414,8 +473,8 @@
 	if (msg_facch) {
 		tx_to_virt_um(l1t, tn, fn, chan, msg_facch);
 		msgb_free(msg_tch);
-	} else
-		tx_to_virt_um(l1t, tn, fn, chan, msg_tch);
+	} else if (msg_tch)
+		tx_to_virt_um_voice_frame(l1t, tn, fn, chan, msg_tch);
 
 send_burst:
 
@@ -456,7 +515,7 @@
 		tx_to_virt_um(l1t, tn, fn, chan, msg_facch);
 		msgb_free(msg_tch);
 	} else if (msg_tch)
-		tx_to_virt_um(l1t, tn, fn, chan, msg_tch);
+		tx_to_virt_um_voice_frame(l1t, tn, fn, chan, msg_tch);
 
 send_burst:
 	return NULL;

-- 
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: I1cd9a251ce0b87181a0822d7940bbfc9f1428543
Gerrit-Change-Number: 17377
Gerrit-PatchSet: 6
Gerrit-Owner: neels <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: laforge <laforge at osmocom.org>
Gerrit-Reviewer: pespin <pespin at sysmocom.de>
Gerrit-CC: fixeria <axilirator at gmail.com>
Gerrit-MessageType: merged
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