Add new ORTP based libosmo-trau based voice support

Using osmo-bts-sysmo and this code, it is now possible to do FR and AMR
based voice calls on TCH/F.

A lot of CPU is wasted in the conversion between the RTP formats and the
L1 specific formats for the codec frames.  All data needs to be shifted
by four bits, and the order of bits needs to be reversed in every byte.

1 files changed, 63 insertions, 27 deletions

diff --git a/src/osmo-bts-sysmo/l1_if.c b/src/osmo-bts-sysmo/l1_if.c
index c97436e6..01f146c6 100644
--- a/src/osmo-bts-sysmo/l1_if.c
+++ b/src/osmo-bts-sysmo/l1_if.c
@@ -165,11 +165,10 @@ struct msgb *sysp_msgb_alloc(void)
 	return msg;
 }
 
-/* prepare a PH-DATA.req primitive in response to a PH-RTS.ind */
-static struct msgb *alloc_ph_data_req(GsmL1_PhReadyToSendInd_t *rts_ind)
+static GsmL1_PhDataReq_t *
+data_req_from_rts_ind(GsmL1_Prim_t *l1p,
+		const GsmL1_PhReadyToSendInd_t *rts_ind)
 {
-	struct msgb *msg = l1p_msgb_alloc();
-	GsmL1_Prim_t *l1p = msgb_l1prim(msg);
 	GsmL1_PhDataReq_t *data_req = &l1p->u.phDataReq;
 
 	l1p->id = GsmL1_PrimId_PhDataReq;
@@ -182,7 +181,25 @@ static struct msgb *alloc_ph_data_req(GsmL1_PhReadyToSendInd_t *rts_ind)
 	data_req->subCh		= rts_ind->subCh;
 	data_req->u8BlockNbr	= rts_ind->u8BlockNbr;
 
-	return msg;
+	return data_req;
+}
+
+static GsmL1_PhEmptyFrameReq_t *
+empty_req_from_rts_ind(GsmL1_Prim_t *l1p,
+			const GsmL1_PhReadyToSendInd_t *rts_ind)
+{
+	GsmL1_PhEmptyFrameReq_t *empty_req = &l1p->u.phEmptyFrameReq;
+
+	l1p->id = GsmL1_PrimId_PhEmptyFrameReq;
+
+	empty_req->hLayer1 = rts_ind->hLayer1;
+	empty_req->u8Tn = rts_ind->u8Tn;
+	empty_req->u32Fn = rts_ind->u32Fn;
+	empty_req->sapi = rts_ind->sapi;
+	empty_req->subCh = rts_ind->subCh;
+	empty_req->u8BlockNbr = rts_ind->u8BlockNbr;
+
+	return empty_req;
 }
 
 /* obtain a ptr to the lapdm_channel for a given hLayer2 */
@@ -208,14 +225,12 @@ static const uint8_t fill_frame[GSM_MACBLOCK_LEN] = {
 static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1,
 				     GsmL1_PhReadyToSendInd_t *rts_ind)
 {
-	struct msgb *resp_msg = alloc_ph_data_req(rts_ind);
 	struct gsm_bts_trx *trx = fl1->priv;
 	struct gsm_bts *bts = trx->bts;
 	struct gsm_bts_role_bts *btsb = bts->role;
-	GsmL1_Prim_t *l1p = msgb_l1prim(resp_msg);
-	GsmL1_PhDataReq_t *data_req = &l1p->u.phDataReq;
-	GsmL1_PhEmptyFrameReq_t *empty_req = &l1p->u.phEmptyFrameReq;
-	GsmL1_MsgUnitParam_t *msu_param = &data_req->msgUnitParam;
+	struct msgb *resp_msg;
+	GsmL1_PhDataReq_t *data_req;
+	GsmL1_MsgUnitParam_t *msu_param;
 	struct lapdm_channel *lc;
 	struct lapdm_entity *le;
 	struct gsm_lchan *lchan;
@@ -231,13 +246,39 @@ static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1,
 		g_time.t1, g_time.t2, g_time.t3,
 		get_value_string(femtobts_l1sapi_names, rts_ind->sapi));
 
-	/* copy over parameters from PH-RTS.ind into PH-DATA.req */
-	data_req->hLayer1 = rts_ind->hLayer1;
-	data_req->u8Tn = rts_ind->u8Tn;
-	data_req->u32Fn = rts_ind->u32Fn;
-	data_req->sapi = rts_ind->sapi;
-	data_req->subCh = rts_ind->subCh;
-	data_req->u8BlockNbr = rts_ind->u8BlockNbr;
+	/* In case of TCH downlink trasnmission, we already have a l1
+	 * primitive msgb pre-allocated and pre-formatted in the
+	 * dl_tch_queue.  All we need to do is to pull it off the queue
+	 * and transmit it */
+	switch (rts_ind->sapi) {
+	case GsmL1_Sapi_TchF:
+	case GsmL1_Sapi_TchH:
+		/* resolve the L2 entity using rts_ind->hLayer2 */
+		lchan = l1if_hLayer2_to_lchan(trx, rts_ind->hLayer2);
+		if (!lchan)
+			break;
+
+		/* get a msgb from the dl_tx_queue */
+		resp_msg = msgb_dequeue(&lchan->dl_tch_queue);
+		if (!resp_msg)
+			break;
+
+		/* fill header */
+		data_req_from_rts_ind(msgb_l1prim(resp_msg), rts_ind);
+		/* actually transmit it */
+		goto tx;
+		break;
+	default:
+		break;
+	}
+
+	/* in all other cases, we need to allocate a new PH-DATA.ind
+	 * primitive msgb and start to fill it */
+	resp_msg = l1p_msgb_alloc();
+	data_req = data_req_from_rts_ind(msgb_l1prim(resp_msg), rts_ind);
+	msu_param = &data_req->msgUnitParam;
+
+	/* set default size */
 	msu_param->u8Size = GSM_MACBLOCK_LEN;
 
 	switch (rts_ind->sapi) {
@@ -306,10 +347,13 @@ static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1,
 		rc = paging_gen_msg(btsb->paging_state, msu_param->u8Buffer, &g_time);
 		break;
 	case GsmL1_Sapi_TchF:
-#warning Send actual speech data on the TCH
+	case GsmL1_Sapi_TchH:
+		/* only hit in case we have a RTP underflow, as real TCH
+		 * frames are handled way above */
 		goto empty_frame;
 		break;
 	case GsmL1_Sapi_FacchF:
+	case GsmL1_Sapi_FacchH:
 		/* resolve the L2 entity using rts_ind->hLayer2 */
 		lc = get_lapdm_chan_by_hl2(trx, rts_ind->hLayer2);
 		le = &lc->lapdm_dcch;
@@ -317,7 +361,6 @@ static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1,
 		if (rc < 0)
 			goto empty_frame;
 		else {
-			data_req->sapi = GsmL1_Sapi_FacchF;
 			memcpy(msu_param->u8Buffer, pp.oph.msg->data, GSM_MACBLOCK_LEN);
 			msgb_free(pp.oph.msg);
 		}
@@ -335,14 +378,7 @@ tx:
 
 empty_frame:
 	/* in case we decide to send an empty frame... */
-	memset(l1p, 0, sizeof(*l1p));
-	l1p->id = GsmL1_PrimId_PhEmptyFrameReq;
-	empty_req->hLayer1 = rts_ind->hLayer1;
-	empty_req->u8Tn = rts_ind->u8Tn;
-	empty_req->u32Fn = rts_ind->u32Fn;
-	empty_req->sapi = rts_ind->sapi;
-	empty_req->subCh = rts_ind->subCh;
-	empty_req->u8BlockNbr = rts_ind->u8BlockNbr;
+	empty_req_from_rts_ind(msgb_l1prim(resp_msg), rts_ind);
 
 	goto tx;
 }