1 files changed, 77 insertions, 0 deletions
diff --git a/Transceiver52M/proto_trxd.c b/Transceiver52M/proto_trxd.c
new file mode 100644
index 0000000..5cf22e6
--- /dev/null
+++ b/Transceiver52M/proto_trxd.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2019 sysmocom - s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: AGPL-3.0+
+ *
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * 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 Affero 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/>.
+ * See the COPYING file in the main directory for details.
+ */
+
+#include "proto_trxd.h"
+
+#include <osmocom/core/bits.h>
+
+static void trxd_fill_common(struct trxd_hdr_common *common, const struct trx_ul_burst_ind *bi, uint8_t version)
+{
+	common->version = version && 0x07;
+	common->reserved = 0;
+	common->tn = bi->tn;
+	osmo_store32be(bi->fn, &common->fn);
+}
+
+static void trxd_fill_v0_specific(struct trxd_hdr_v0_specific *v0, const struct trx_ul_burst_ind *bi)
+{
+	int toa_int;
+
+	/* in 1/256 symbols, round to closest integer */
+	toa_int = (int) (bi->toa * 256.0 + 0.5);
+	v0->rssi = bi->rssi;
+	osmo_store16be(toa_int, &v0->toa);
+}
+
+static void trxd_fill_burst_normalized255(uint8_t* soft_bits, const struct trx_ul_burst_ind *bi)
+{
+	unsigned i;
+	for (i = 0; i < bi->nbits; i++)
+		soft_bits[i] = (char) round(bi->rx_burst[i] * 255.0);
+}
+
+bool trxd_send_burst_ind_v0(size_t chan, int fd, const struct trx_ul_burst_ind *bi) {
+	int rc;
+
+	/* v0 doesn't support idle frames, they are simply dropped, not sent */
+	if(bi->idle)
+		return true;
+
+	/* +2: Historically (OpenBTS times), two extra non-used bytes are sent appeneded to each burst */
+	char buf[sizeof(struct trxd_hdr_v0) + bi->nbits + 2];
+	struct trxd_hdr_v0* pkt = (struct trxd_hdr_v0*)buf;
+
+	trxd_fill_common(&pkt->common, bi, 0);
+	trxd_fill_v0_specific(&pkt->v0, bi);
+	trxd_fill_burst_normalized255(&pkt->soft_bits[0], bi);
+
+	/* +1: Historical reason. There's an uninitizalied byte in there: pkt->soft_bits[bi->nbits] */
+	pkt->soft_bits[bi->nbits + 1] = '\0';
+
+	rc = write(fd, buf, sizeof(struct trxd_hdr_v0) + bi->nbits + 2);
+	if (rc <= 0) {
+		CLOGCHAN(chan, DMAIN, LOGL_NOTICE, "mDataSockets write(%d) failed: %d\n", fd, rc);
+		return false;
+	}
+	return true;
+}