initial import of Osmocom TETRA phy and lower MAC code

2025-06-12 03:44:18 +02:00 · 2011-01-19 10:39:59 +01:00 · 2011-01-19 10:39:59 +01:00 · 7ee08faee0
commit 7ee08faee0
parent a4c4e5a1ab
45 changed files with 4217 additions and 0 deletions
--- a/src/phy/tetra_burst_sync.c
+++ b/src/phy/tetra_burst_sync.c
@ -0,0 +1,141 @@
+/* Implementation of TETRA burst synchronization */
+
+/* (C) 2011 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 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/>.
+ *
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <osmocore/utils.h>
+
+//#define DEBUG
+
+#include <tetra_common.h>
+#include <phy/tetra_burst.h>
+#include <tetra_tdma.h>
+#include <phy/tetra_burst_sync.h>
+
+struct tetra_phy_state t_phy_state;
+
+void tetra_burst_rx_cb(const uint8_t *burst, unsigned int len, enum tetra_train_seq type, void *priv);
+
+/* input a raw bitstream into the tetra burst synchronizaer */
+int tetra_burst_sync_in(struct tetra_rx_state *trs, uint8_t *bits, unsigned int len)
+{
+	int rc;
+	unsigned int train_seq_offs;
+	int cpy_len;
+
+	DEBUGP("burst_sync_in: %u bits, state %u\n", len, trs->state);
+
+	/* First: append the data to the bitbuf */
+	if (sizeof(trs->bitbuf) - trs->bits_in_buf < len)
+		cpy_len = sizeof(trs->bitbuf) - trs->bits_in_buf;
+	else
+		cpy_len = len;
+	memcpy(trs->bitbuf + trs->bits_in_buf, bits, cpy_len);
+	trs->bits_in_buf += cpy_len;
+
+	switch (trs->state) {
+	case RX_S_UNLOCKED:
+		if (trs->bits_in_buf < TETRA_BITS_PER_TS*2) {
+			/* wait for more bits to arrive */
+			DEBUGP("-> waiting for more bits to arrive\n");
+			return cpy_len;
+		}
+		DEBUGP("-> trying to find training sequence between bit %u and %u\n",
+			trs->bitbuf_start_bitnum, trs->bits_in_buf);
+		rc = tetra_find_train_seq(trs->bitbuf, trs->bits_in_buf,
+					  (1 << TETRA_TRAIN_SYNC), &train_seq_offs);
+		if (rc < 0)
+			return rc;
+		printf("found SYNC training sequence in bit #%u\n", train_seq_offs);
+		trs->state = RX_S_KNOW_FSTART;
+		trs->next_frame_start_bitnum = trs->bitbuf_start_bitnum + train_seq_offs + 296;
+#if 0
+		if (train_seq_offs < 214) {
+			/* not enough leading bits for start of burst */
+			/* we just drop everything that we received so far */
+			trs->bitbuf_start_bitnum += trs->bits_in_buf;
+			trs->bits_in_buf = 0;
+		}
+#endif
+		break;
+	case RX_S_KNOW_FSTART:
+		/* we are locked, i.e. already know when the next frame should start */
+		if (trs->bitbuf_start_bitnum + trs->bits_in_buf < trs->next_frame_start_bitnum)
+			return 0;
+		else {
+			/* shift start of frame to start of bitbuf */
+			int offset = trs->next_frame_start_bitnum - trs->bitbuf_start_bitnum;
+			int bits_remaining = trs->bits_in_buf - offset;
+
+			memmove(trs->bitbuf, trs->bitbuf+offset, bits_remaining);
+			trs->bits_in_buf = bits_remaining;
+			trs->bitbuf_start_bitnum += offset;
+
+			trs->next_frame_start_bitnum += TETRA_BITS_PER_TS;
+			trs->state = RX_S_LOCKED;
+		}
+	case RX_S_LOCKED:
+		if (trs->bits_in_buf < TETRA_BITS_PER_TS) {
+			/* not sufficient data for the full frame yet */
+			return cpy_len;
+		} else {
+			/* we have successfully received (at least) one frame */
+			tetra_tdma_time_add_tn(&t_phy_state.time, 1);
+			printf("\nBURST: %s\n", bitdump(trs->bitbuf, TETRA_BITS_PER_TS));
+			rc = tetra_find_train_seq(trs->bitbuf, trs->bits_in_buf,
+						  (1 << TETRA_TRAIN_NORM_1)|
+						  (1 << TETRA_TRAIN_NORM_2)|
+						  (1 << TETRA_TRAIN_SYNC), &train_seq_offs);
+			switch (rc) {
+			case TETRA_TRAIN_SYNC:
+				if (train_seq_offs == 214)
+					tetra_burst_rx_cb(trs->bitbuf, TETRA_BITS_PER_TS, rc, trs->burst_cb_priv);
+				else {
+					fprintf(stderr, "#### SYNC burst at offset %u?!?\n", train_seq_offs);
+					trs->state = RX_S_UNLOCKED;
+				}
+				break;
+			case TETRA_TRAIN_NORM_1:
+			case TETRA_TRAIN_NORM_2:
+			case TETRA_TRAIN_NORM_3:
+				if (train_seq_offs == 244)
+					tetra_burst_rx_cb(trs->bitbuf, TETRA_BITS_PER_TS, rc, trs->burst_cb_priv);
+				else
+					fprintf(stderr, "#### SYNC burst at offset %u?!?\n", train_seq_offs);
+				break;
+			default:
+				fprintf(stderr, "#### could not find successive burst training sequence\n");
+				trs->state = RX_S_UNLOCKED;
+				break;
+			}
+
+			/* move remainder to start of buffer */
+			trs->bits_in_buf -= TETRA_BITS_PER_TS;
+			memmove(trs->bitbuf, trs->bitbuf+TETRA_BITS_PER_TS, trs->bits_in_buf);
+			trs->bitbuf_start_bitnum += TETRA_BITS_PER_TS;
+			trs->next_frame_start_bitnum += TETRA_BITS_PER_TS;
+		}
+		break;
+
+	}
+	return cpy_len;
+}