3 files changed, 112 insertions, 19 deletions

diff --git a/src/common/bts.c b/src/common/bts.c
index b4a5f804..7257f37b 100644
--- a/src/common/bts.c
+++ b/src/common/bts.c
@@ -56,6 +56,7 @@
 #include <osmo-bts/nm_common_fsm.h>
 #include <osmo-bts/power_control.h>
 #include <osmo-bts/osmux.h>
+#include <osmo-bts/notification.h>
 
 #define MIN_QUAL_RACH	 50 /* minimum link quality (in centiBels) for Access Bursts */
 #define MIN_QUAL_NORM	 -5 /* minimum link quality (in centiBels) for Normal Bursts */
@@ -723,8 +724,7 @@ static void compact_agch_queue(struct gsm_bts *bts)
 	return;
 }
 
-int bts_ccch_copy_msg(struct gsm_bts *bts, uint8_t *out_buf, struct gsm_time *gt,
-		      int is_ag_res)
+int bts_ccch_copy_msg(struct gsm_bts *bts, uint8_t *out_buf, struct gsm_time *gt, enum ccch_msgt ccch)
 {
 	struct msgb *msg = NULL;
 	int rc = 0;
@@ -737,17 +737,25 @@ int bts_ccch_copy_msg(struct gsm_bts *bts, uint8_t *out_buf, struct gsm_time *gt
 	 */
 	compact_agch_queue(bts);
 
-	/* Check for paging messages first if this is PCH */
-	if (!is_ag_res)
-		rc = paging_gen_msg(bts->paging_state, out_buf, gt, &is_empty);
-
-	/* Check whether the block may be overwritten */
-	if (!is_empty)
-		return rc;
-
-	msg = bts_agch_dequeue(bts);
-	if (!msg)
+	switch (ccch) {
+	case CCCH_MSGT_NCH:
+		/* Send NCH message, it has priority over AGCH and does not overlap with PCH. */
+		rc = bts_asci_notify_nch_gen_msg(bts, out_buf);
 		return rc;
+	case CCCH_MSGT_PCH:
+		/* Check whether the block may be overwritten by AGCH. */
+		rc = paging_gen_msg(bts->paging_state, out_buf, gt, &is_empty);
+		if (!is_empty)
+			return rc;
+		/* fall-through */
+	case CCCH_MSGT_AGCH:
+		/* If fallen here and the AGCH queue is empty, return empty PCH message. */
+		msg = bts_agch_dequeue(bts);
+		if (!msg)
+			return rc;
+		/* Continue to return AGCH message. */
+		break;
+	}
 
 	rate_ctr_inc2(bts->ctrs, BTS_CTR_AGCH_SENT);
 
@@ -756,7 +764,7 @@ int bts_ccch_copy_msg(struct gsm_bts *bts, uint8_t *out_buf, struct gsm_time *gt
 	rc = msgb_l3len(msg);
 	msgb_free(msg);
 
-	if (is_ag_res)
+	if (ccch == CCCH_MSGT_AGCH)
 		bts->agch_queue.agch_msgs++;
 	else
 		bts->agch_queue.pch_msgs++;
diff --git a/src/common/l1sap.c b/src/common/l1sap.c
index 1c43f8ff..268486e0 100644
--- a/src/common/l1sap.c
+++ b/src/common/l1sap.c
@@ -902,15 +902,32 @@ static int lchan_pdtch_ph_rts_ind_loop(struct gsm_lchan *lchan,
 	return 0;
 }
 
-/* Check if given CCCH frame number is for a PCH or for an AGCH (this function is
+/* Check if given CCCH frame number is for a NCH, PCH or for an AGCH (this function is
  * only used internally, it is public to call it from unit-tests) */
-int is_ccch_for_agch(struct gsm_bts_trx *trx, uint32_t fn) {
+enum ccch_msgt get_ccch_msgt(struct gsm_bts_trx *trx, uint32_t fn)
+{
+	uint8_t block, first_block, num_blocks;
+	int rc;
+
+	block = l1sap_fn2ccch_block(fn);
+
+	/* If there is an NCH, check if the block number matches. It has priority over PCH/AGCH. */
+	if (trx->bts->asci.pos_nch >= 0) {
+		rc = osmo_gsm48_si1ro_nch_pos_decode(trx->bts->asci.pos_nch, &num_blocks, &first_block);
+		if (rc >= 0 && block >= first_block && block < first_block + num_blocks)
+			return CCCH_MSGT_NCH;
+	}
+
 	/* Note: The number of available access grant channels is set by the
 	 * parameter BS_AG_BLKS_RES via system information type 3. This SI is
 	 * transferred to osmo-bts via RSL */
-        return l1sap_fn2ccch_block(fn) < num_agch(trx, "PH-RTS-IND");
+	if (l1sap_fn2ccch_block(fn) < num_agch(trx, "PH-RTS-IND"))
+		return CCCH_MSGT_AGCH;
+
+	return CCCH_MSGT_PCH;
 }
 
+
 /* return the measured average of frame numbers that the RTS clock is running in advance */
 int32_t bts_get_avg_fn_advance(const struct gsm_bts *bts)
 {
@@ -1048,7 +1065,6 @@ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx,
 	struct msgb *pp_msg;
 	bool dtxd_facch = false;
 	int rc;
-	int is_ag_res;
 
 	chan_nr = rts_ind->chan_nr;
 	link_id = rts_ind->link_id;
@@ -1183,8 +1199,7 @@ static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx,
 		}
 	} else if (L1SAP_IS_CHAN_AGCH_PCH(chan_nr)) {
 		p = msgb_put(msg, GSM_MACBLOCK_LEN);
-		is_ag_res = is_ccch_for_agch(trx, fn);
-		rc = bts_ccch_copy_msg(trx->bts, p, &g_time, is_ag_res);
+		rc = bts_ccch_copy_msg(trx->bts, p, &g_time, get_ccch_msgt(trx, fn));
 		if (rc <= 0)
 			memcpy(p, fill_frame, GSM_MACBLOCK_LEN);
 	}
diff --git a/src/common/notification.c b/src/common/notification.c
index 1fda5194..35dc65f9 100644
--- a/src/common/notification.c
+++ b/src/common/notification.c
@@ -71,6 +71,10 @@ int bts_asci_notification_add(struct gsm_bts *bts, const uint8_t *group_call_ref
 	/* add at beginning of "queue" to make sure a new call is notified first */
 	llist_add(&n->list, &bts->asci.notifications);
 
+	bts->asci.notification_entries++;
+	bts->asci.notification_count = 0;
+	bts->asci.nln = (bts->asci.nln + 1) % 4;
+
 	return 0;
 }
 
@@ -86,6 +90,10 @@ int bts_asci_notification_del(struct gsm_bts *bts, const uint8_t *group_call_ref
 	llist_del(&n->list);
 	talloc_free(n);
 
+	bts->asci.notification_entries--;
+	bts->asci.notification_count = 0;
+	bts->asci.nln_status = (bts->asci.nln_status + 1) % 2;
+
 	return 0;
 }
 
@@ -100,6 +108,11 @@ int bts_asci_notification_reset(struct gsm_bts *bts)
 		llist_del(&n->list);
 		talloc_free(n);
 	}
+
+	bts->asci.notification_entries = 0;
+	bts->asci.notification_count = 0;
+	bts->asci.nln_status = (bts->asci.nln_status + 1) % 2;
+
 	return 0;
 }
 
@@ -153,3 +166,60 @@ void append_group_call_information(struct bitvec *bv, const uint8_t *gcr, const
 
 	bitvec_free(gcr_bv);
 }
+
+#define L2_PLEN(len)	(((len - 1) << 2) | 0x01)
+
+int bts_asci_notify_nch_gen_msg(struct gsm_bts *bts, uint8_t *out_buf)
+{
+	struct gsm48_notification_nch *nn = (struct gsm48_notification_nch *) out_buf;
+	const struct asci_notification *notif;
+	unsigned int ro_len;
+
+	notif = bts_asci_notification_get_next(bts);
+
+	*nn = (struct gsm48_notification_nch) {
+		.proto_discr = GSM48_PDISC_RR,
+		.msg_type = GSM48_MT_RR_NOTIF_NCH,
+	};
+
+	nn->l2_plen = L2_PLEN(nn->data - out_buf);
+
+	/* Pad remaining octets with constant '2B'O */
+	ro_len = GSM_MACBLOCK_LEN - (nn->data - out_buf);
+	memset(nn->data, GSM_MACBLOCK_PADDING, ro_len);
+
+	struct bitvec bv = {
+		.data_len = ro_len,
+		.data = nn->data,
+	};
+
+	/* {0 | 1 < NLN(NCH) : bit (2) >}
+	 * Only send NLN, at the last notifications.
+	 * When the phone receives two NLN with the same value, it knows that all notifications has been received.
+	 * Also send NLN if no notification is available. */
+	if (bts->asci.notification_count >= bts->asci.notification_entries - 1) {
+		bitvec_set_bit(&bv, 1);
+		bitvec_set_uint(&bv, bts->asci.nln, 2);
+	} else {
+		bitvec_set_bit(&bv, 0);
+	}
+
+	/* Count NLN. */
+	if (++bts->asci.notification_count >= bts->asci.notification_entries)
+		bts->asci.notification_count = 0;
+
+	/* < List of Group Call NCH information > ::=
+	 *   { 0 | 1 < Group Call information > < List of Group Call NCH information > } ; */
+	if (notif) {
+		bitvec_set_bit(&bv, 1);
+		append_group_call_information(&bv, notif->group_call_ref,
+						   notif->chan_desc.present ? notif->chan_desc.value : NULL,
+						   notif->chan_desc.len);
+	}
+	bitvec_set_bit(&bv, 0);	/* End of list */
+
+	/* TODO: Additions in Release 6 */
+	/* TODO: Additions in Release 7 */
+
+	return GSM_MACBLOCK_LEN;
+}