summaryrefslogtreecommitdiffstats
path: root/src/host/trxcon/sched_lchan_tchh.c
blob: 172f54b44f6057583e92e627bba228ca1073bb3e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
/*
 * OsmocomBB <-> SDR connection bridge
 * TDMA scheduler: handlers for DL / UL bursts on logical channels
 *
 * (C) 2018 by Vadim Yanitskiy <axilirator@gmail.com>
 * (C) 2018 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 General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <errno.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>

#include <osmocom/core/logging.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/bits.h>

#include <osmocom/gsm/protocol/gsm_04_08.h>
#include <osmocom/gsm/gsm_utils.h>

#include <osmocom/coding/gsm0503_coding.h>
#include <osmocom/codec/codec.h>

#include "l1ctl_proto.h"
#include "scheduler.h"
#include "sched_trx.h"
#include "logging.h"
#include "trx_if.h"
#include "l1ctl.h"

static const uint8_t tch_h0_traffic_block_map[3][4] = {
	/* B0(0,2,4,6), B1(4,6,8,10), B2(8,10,0,2) */
	{ 0, 2, 4, 6 },
	{ 4, 6, 8, 10 },
	{ 8, 10, 0, 2 },
};

static const uint8_t tch_h1_traffic_block_map[3][4] = {
	/* B0(1,3,5,7), B1(5,7,9,11), B2(9,11,1,3) */
	{ 1, 3, 5, 7 },
	{ 5, 7, 9, 11 },
	{ 9, 11, 1, 3 },
};

static const uint8_t tch_h0_dl_facch_block_map[3][6] = {
	/* B0(4,6,8,10,13,15), B1(13,15,17,19,21,23), B2(21,23,0,2,4,6) */
	{ 4, 6, 8, 10, 13, 15 },
	{ 13, 15, 17, 19, 21, 23 },
	{ 21, 23, 0, 2, 4, 6 },
};

static const uint8_t tch_h0_ul_facch_block_map[3][6] = {
	/* B0(0,2,4,6,8,10), B1(8,10,13,15,17,19), B2(17,19,21,23,0,2) */
	{ 0, 2, 4, 6, 8, 10 },
	{ 8, 10, 13, 15, 17, 19 },
	{ 17, 19, 21, 23, 0, 2 },
};

static const uint8_t tch_h1_dl_facch_block_map[3][6] = {
	/* B0(5,7,9,11,14,16), B1(14,16,18,20,22,24), B2(22,24,1,3,5,7) */
	{ 5, 7, 9, 11, 14, 16 },
	{ 14, 16, 18, 20, 22, 24 },
	{ 22, 24, 1, 3, 5, 7 },
};

const uint8_t tch_h1_ul_facch_block_map[3][6] = {
	/* B0(1,3,5,7,9,11), B1(9,11,14,16,18,20), B2(18,20,22,24,1,3) */
	{ 1, 3, 5, 7, 9, 11 },
	{ 9, 11, 14, 16, 18, 20 },
	{ 18, 20, 22, 24, 1, 3 },
};

/**
 * Can a TCH/H block transmission be initiated / finished
 * on a given frame number and a given channel type?
 *
 * See GSM 05.02, clause 7, table 1
 *
 * @param  chan   channel type (TRXC_TCHH_0 or TRXC_TCHH_1)
 * @param  fn     the current frame number
 * @param  ul     Uplink or Downlink?
 * @param  facch  FACCH/H or traffic?
 * @param  start  init or end of transmission?
 * @return        true (yes) or false (no)
 */
bool sched_tchh_block_map_fn(enum trx_lchan_type chan,
	uint32_t fn, bool ul, bool facch, bool start)
{
	uint8_t fn_mf;
	int i = 0;

	/* Just to be sure */
	OSMO_ASSERT(chan == TRXC_TCHH_0 || chan == TRXC_TCHH_1);

	/* Calculate a modulo */
	fn_mf = facch ? (fn % 26) : (fn % 13);

#define MAP_GET_POS(map) \
	(start ? 0 : ARRAY_SIZE(map[i]) - 1)

#define BLOCK_MAP_FN(map) \
	do { \
		if (map[i][MAP_GET_POS(map)] == fn_mf) \
			return true; \
	} while (++i < ARRAY_SIZE(map))

	/* Choose a proper block map */
	if (facch) {
		if (ul) {
			if (chan == TRXC_TCHH_0)
				BLOCK_MAP_FN(tch_h0_ul_facch_block_map);
			else
				BLOCK_MAP_FN(tch_h1_ul_facch_block_map);
		} else {
			if (chan == TRXC_TCHH_0)
				BLOCK_MAP_FN(tch_h0_dl_facch_block_map);
			else
				BLOCK_MAP_FN(tch_h1_dl_facch_block_map);
		}
	} else {
		if (chan == TRXC_TCHH_0)
			BLOCK_MAP_FN(tch_h0_traffic_block_map);
		else
			BLOCK_MAP_FN(tch_h1_traffic_block_map);
	}

	return false;
}

/**
 * Calculates a frame number of the first burst
 * using given frame number of the last burst.
 *
 * See GSM 05.02, clause 7, table 1
 *
 * @param  chan      channel type (TRXC_TCHH_0 or TRXC_TCHH_1)
 * @param  last_fn   frame number of the last burst
 * @param  facch     FACCH/H or traffic?
 * @return           either frame number of the first burst,
 *                   or fn=last_fn if calculation failed
 */
uint32_t sched_tchh_block_dl_first_fn(enum trx_lchan_type chan,
	uint32_t last_fn, bool facch)
{
	uint8_t fn_mf, fn_diff;
	int i = 0;

	/* Just to be sure */
	OSMO_ASSERT(chan == TRXC_TCHH_0 || chan == TRXC_TCHH_1);

	/* Calculate a modulo */
	fn_mf = facch ? (last_fn % 26) : (last_fn % 13);

#define BLOCK_FIRST_FN(map) \
	do { \
		if (map[i][ARRAY_SIZE(map[i]) - 1] == fn_mf) { \
			fn_diff = TDMA_FN_DIFF(fn_mf, map[i][0]); \
			return TDMA_FN_SUB(last_fn, fn_diff); \
		} \
	} while (++i < ARRAY_SIZE(map))

	/* Choose a proper block map */
	if (facch) {
		if (chan == TRXC_TCHH_0)
			BLOCK_FIRST_FN(tch_h0_dl_facch_block_map);
		else
			BLOCK_FIRST_FN(tch_h1_dl_facch_block_map);
	} else {
		if (chan == TRXC_TCHH_0)
			BLOCK_FIRST_FN(tch_h0_traffic_block_map);
		else
			BLOCK_FIRST_FN(tch_h1_traffic_block_map);
	}

	LOGP(DSCHD, LOGL_ERROR, "Failed to calculate TDMA "
		"frame number of the first burst of %s block, "
		"using the current fn=%u\n", facch ?
			"FACCH/H" : "TCH/H", last_fn);

	/* Couldn't calculate the first fn, return the last */
	return last_fn;
}

int rx_tchh_fn(struct trx_instance *trx, struct trx_ts *ts,
	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
	sbit_t *bits, int8_t rssi, int16_t toa256)
{
	const struct trx_lchan_desc *lchan_desc;
	int n_errors = -1, n_bits_total, rc;
	sbit_t *buffer, *offset;
	uint8_t l2[128], *mask;
	size_t l2_len;

	/* Set up pointers */
	lchan_desc = &trx_lchan_desc[lchan->type];
	mask = &lchan->rx_burst_mask;
	buffer = lchan->rx_bursts;

	LOGP(DSCHD, LOGL_DEBUG, "Traffic received on %s: fn=%u ts=%u bid=%u\n",
		lchan_desc->name, fn, ts->index, bid);

	if (*mask == 0x00) {
		/* Align to the first burst */
		if (bid > 0)
			return 0;

		/* Align reception of the first FACCH/H frame */
		if (lchan->tch_mode == GSM48_CMODE_SIGN) {
			if (!sched_tchh_facch_start(lchan->type, fn, 0))
				return 0;
		} else { /* or TCH/H traffic frame */
			if (!sched_tchh_traffic_start(lchan->type, fn, 0))
				return 0;
		}
	}

	/* Update mask */
	*mask |= (1 << bid);

	/**
	 * FIXME: properly update measurements
	 *
	 * Since TCH/H channel is using block-diagonal interleaving,
	 * a single burst may carry 57 bits of one encoded frame,
	 * and 57 bits of another. This should be taken into account.
	 */
	lchan->meas.rssi_sum += rssi;
	lchan->meas.toa256_sum += toa256;
	lchan->meas.num++;

	/* Copy burst to the end of buffer of 6 bursts */
	offset = buffer + bid * 116 + 464;
	memcpy(offset, bits + 3, 58);
	memcpy(offset + 58, bits + 87, 58);

	/* Wait until the second burst */
	if (bid != 1)
		return 0;

	/* Wait for complete set of bursts */
	if (lchan->tch_mode == GSM48_CMODE_SIGN) {
		/* FACCH/H is interleaved over 6 bursts */
		if ((*mask & 0x3f) != 0x3f)
			goto bfi_shift;
	} else {
		/* Traffic is interleaved over 4 bursts */
		if ((*mask & 0x0f) != 0x0f)
			goto bfi_shift;
	}

	/* Skip decoding attempt in case of FACCH/H */
	if (lchan->dl_ongoing_facch) {
		lchan->dl_ongoing_facch = false;
		goto bfi_shift; /* 2/2 BFI */
	}

	switch (lchan->tch_mode) {
	case GSM48_CMODE_SIGN:
	case GSM48_CMODE_SPEECH_V1: /* HR */
		rc = gsm0503_tch_hr_decode(l2, buffer,
			!sched_tchh_facch_end(lchan->type, fn, 0),
			&n_errors, &n_bits_total);
		break;
	case GSM48_CMODE_SPEECH_AMR: /* AMR */
		/**
		 * TODO: AMR requires a dedicated loop,
		 * which will be implemented later...
		 */
		LOGP(DSCHD, LOGL_ERROR, "AMR isn't supported yet\n");
		return -ENOTSUP;
	default:
		LOGP(DSCHD, LOGL_ERROR, "Invalid TCH mode: %u\n", lchan->tch_mode);
		return -EINVAL;
	}

	/* Shift buffer by 4 bursts for interleaving */
	memcpy(buffer, buffer + 232, 232);
	memcpy(buffer + 232, buffer + 464, 232);

	/* Shift burst mask */
	*mask = *mask << 2;

	/* Check decoding result */
	if (rc < 4) {
		LOGP(DSCHD, LOGL_ERROR, "Received bad TCH frame ending at "
			"fn=%u on %s (rc=%d)\n", fn, lchan_desc->name, rc);

		/* Send BFI */
		goto bfi;
	} else if (rc == GSM_MACBLOCK_LEN) {
		/* Skip decoding of the next 2 stolen bursts */
		lchan->dl_ongoing_facch = true;

		/* Calculate TDMA frame number of the first burst */
		lchan->rx_first_fn = sched_tchh_block_dl_first_fn(lchan->type,
			fn, true); /* FACCH/H */

		/* FACCH/H received, forward to the higher layers */
		sched_send_dt_ind(trx, ts, lchan, l2, GSM_MACBLOCK_LEN,
			n_errors, false, false);

		/* 1/2 BFI */
		goto bfi;
	} else {
		/* A good TCH frame received */
		l2_len = rc;
	}

	/* Calculate TDMA frame number of the first burst */
	lchan->rx_first_fn = sched_tchh_block_dl_first_fn(lchan->type,
		fn, false); /* TCH/H */

	/* Send a traffic frame to the higher layers */
	return sched_send_dt_ind(trx, ts, lchan, l2, l2_len,
		n_errors, false, true);

bfi_shift:
	/* Shift buffer */
	memcpy(buffer, buffer + 232, 232);
	memcpy(buffer + 232, buffer + 464, 232);

	/* Shift burst mask */
	*mask = *mask << 2;

bfi:
	/* Didn't try to decode */
	if (n_errors < 0)
		n_errors = 116 * 2;

	/* Calculate TDMA frame number of the first burst */
	lchan->rx_first_fn = sched_tchh_block_dl_first_fn(lchan->type,
		fn, false); /* TCH/H */

	/* BFI is not applicable in signalling mode */
	if (lchan->tch_mode == GSM48_CMODE_SIGN)
		return sched_send_dt_ind(trx, ts, lchan, NULL, 0,
			n_errors, true, false);

	/* Bad frame indication */
	l2_len = sched_bad_frame_ind(l2, lchan);

	/* Send a BFI frame to the higher layers */
	return sched_send_dt_ind(trx, ts, lchan, l2, l2_len,
		n_errors, true, true);
}

int tx_tchh_fn(struct trx_instance *trx, struct trx_ts *ts,
	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid)
{
	const struct trx_lchan_desc *lchan_desc;
	ubit_t burst[GSM_BURST_LEN];
	ubit_t *buffer, *offset;
	const uint8_t *tsc;
	uint8_t *mask;
	size_t l2_len;
	int rc;

	/* Set up pointers */
	lchan_desc = &trx_lchan_desc[lchan->type];
	mask = &lchan->tx_burst_mask;
	buffer = lchan->tx_bursts;

	if (bid > 0) {
		/* Align to the first burst */
		if (*mask == 0x00)
			return 0;
		goto send_burst;
	}

	if (*mask == 0x00) {
		/* Align transmission of the first FACCH/H frame */
		if (lchan->tch_mode == GSM48_CMODE_SIGN)
			if (!sched_tchh_facch_start(lchan->type, fn, 1))
				return 0;
	}

	/* Shift buffer by 2 bursts back for interleaving */
	memcpy(buffer, buffer + 232, 232);

	/* Also shift TX burst mask */
	*mask = *mask << 2;

	/* If FACCH/H blocks are still pending */
	if (lchan->ul_facch_blocks > 2) {
		memcpy(buffer + 232, buffer + 464, 232);
		goto send_burst;
	}

	/* Check the current TCH mode */
	switch (lchan->tch_mode) {
	case GSM48_CMODE_SIGN:
	case GSM48_CMODE_SPEECH_V1: /* HR */
		l2_len = GSM_HR_BYTES + 1;
		break;
	case GSM48_CMODE_SPEECH_AMR: /* AMR */
		/**
		 * TODO: AMR requires a dedicated loop,
		 * which will be implemented later...
		 */
		LOGP(DSCHD, LOGL_ERROR, "AMR isn't supported yet, "
			"dropping frame...\n");

		/* Forget this primitive */
		sched_prim_drop(lchan);
		return -ENOTSUP;
	default:
		LOGP(DSCHD, LOGL_ERROR, "Invalid TCH mode: %u, "
			"dropping frame...\n", lchan->tch_mode);

		/* Forget this primitive */
		sched_prim_drop(lchan);
		return -EINVAL;
	}

	/* Determine payload length */
	if (PRIM_IS_FACCH(lchan->prim)) {
		l2_len = GSM_MACBLOCK_LEN; /* FACCH */
	} else if (lchan->prim->payload_len != l2_len) {
		LOGP(DSCHD, LOGL_ERROR, "Primitive has odd length %zu "
			"(expected %zu for TCH or %u for FACCH), so dropping...\n",
			lchan->prim->payload_len, l2_len, GSM_MACBLOCK_LEN);

		/* Forget this primitive */
		sched_prim_drop(lchan);
		return -EINVAL;
	}

	/* Encode the payload */
	rc = gsm0503_tch_hr_encode(buffer, lchan->prim->payload, l2_len);
	if (rc) {
		LOGP(DSCHD, LOGL_ERROR, "Failed to encode L2 payload\n");

		/* Forget this primitive */
		sched_prim_drop(lchan);
		return -EINVAL;
	}

	/* A FACCH/H frame occupies 6 bursts */
	if (PRIM_IS_FACCH(lchan->prim))
		lchan->ul_facch_blocks = 6;

send_burst:
	/* Determine which burst should be sent */
	offset = buffer + bid * 116;

	/* Update mask */
	*mask |= (1 << bid);

	/* Choose proper TSC */
	tsc = sched_nb_training_bits[trx->tsc];

	/* Compose a new burst */
	memset(burst, 0, 3); /* TB */
	memcpy(burst + 3, offset, 58); /* Payload 1/2 */
	memcpy(burst + 61, tsc, 26); /* TSC */
	memcpy(burst + 87, offset + 58, 58); /* Payload 2/2 */
	memset(burst + 145, 0, 3); /* TB */

	LOGP(DSCHD, LOGL_DEBUG, "Transmitting %s fn=%u ts=%u burst=%u\n",
		lchan_desc->name, fn, ts->index, bid);

	/* Forward burst to transceiver */
	sched_trx_handle_tx_burst(trx, ts, lchan, fn, burst);

	/* In case of a FACCH/H frame, one block less */
	if (lchan->ul_facch_blocks)
		lchan->ul_facch_blocks--;

	if ((*mask & 0x0f) == 0x0f) {
		/**
		 * If no more FACCH/H blocks pending,
		 * confirm data / traffic sending
		 */
		if (!lchan->ul_facch_blocks)
			sched_send_dt_conf(trx, ts, lchan, fn,
				PRIM_IS_TCH(lchan->prim));

		/* Forget processed primitive */
		sched_prim_drop(lchan);
	}

	return 0;
}