1 files changed, 67 insertions, 0 deletions
diff --git a/src/common/tch.c b/src/common/tch.c
new file mode 100644
index 00000000..d31b04ef
--- /dev/null
+++ b/src/common/tch.c
@@ -0,0 +1,67 @@
+/* OsmoBTS common TCH code */
+
+/* (C) 2011-2012 by Harald Welte <laforge@gnumonks.org>
+ *
+ * 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/gsm_data.h>
+
+extern struct msgb *l1p_msgb_alloc(void);
+extern uint8_t *get_payload_addr(struct msgb *msg);
+extern void set_payload_type(struct msgb *msg, struct gsm_lchan *lchan);
+extern void set_payload_size(struct msgb *msg, uint8_t size);
+
+struct msgb *gen_empty_tch_msg(struct gsm_lchan *lchan)
+{
+	struct msgb *msg;
+	uint8_t *l1_payload;
+
+	msg = l1p_msgb_alloc();
+	if (!msg)
+		return NULL;
+
+	l1_payload = get_payload_addr(msg);
+
+	switch (lchan->tch_mode) {
+	case GSM48_CMODE_SPEECH_AMR:
+		set_payload_type(msg, lchan);
+		if (lchan->tch.last_sid.len) {
+			memcpy(l1_payload, lchan->tch.last_sid.buf,
+				lchan->tch.last_sid.len);
+			set_payload_size(msg, lchan->tch.last_sid.len + 1);
+		} else {
+			/* FIXME: decide if we should send SPEECH_BAD or
+			 * SID_BAD */
+#if 0
+			*payload_type = GsmL1_TchPlType_Amr_SidBad;
+			memset(l1_payload, 0xFF, 5);
+			msu_param->u8Size = 5 + 3;
+#else
+			/* send an all-zero SID */
+			set_payload_size(msg, 8);
+#endif
+		}
+		break;
+	default:
+		msgb_free(msg);
+		msg = NULL;
+		break;
+	}
+
+	return msg;
+}