367 lines
10 KiB
C
367 lines
10 KiB
C
/*
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* OsmocomBB <-> SDR connection bridge
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* TDMA scheduler: handlers for DL / UL bursts on logical channels
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*
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* (C) 2017-2022 by Vadim Yanitskiy <axilirator@gmail.com>
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* Contributions by sysmocom - s.f.m.c. GmbH
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <errno.h>
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#include <string.h>
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#include <stdint.h>
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#include <osmocom/core/logging.h>
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#include <osmocom/core/bits.h>
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#include <osmocom/gsm/protocol/gsm_04_08.h>
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#include <osmocom/gsm/gsm_utils.h>
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#include <osmocom/coding/gsm0503_coding.h>
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#include <osmocom/coding/gsm0503_amr_dtx.h>
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#include <osmocom/codec/codec.h>
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#include <osmocom/bb/l1sched/l1sched.h>
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#include <osmocom/bb/l1sched/logging.h>
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#include <osmocom/bb/trxcon/sched_utils.h>
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/* 3GPP TS 45.009, table 3.2.1.3-{1,3}: AMR on Downlink TCH/F.
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*
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* +---+---+---+---+---+---+---+---+
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* | a | b | c | d | e | f | g | h | Burst 'a' received first
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* +---+---+---+---+---+---+---+---+
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* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Speech/FACCH frame (bursts 'a' .. 'h')
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*
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* TDMA frame number of burst 'h' is always used as the table index. */
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static const uint8_t sched_tchf_dl_amr_cmi_map[26] = {
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[11] = 1, /* TCH/F: a=4 / h=11 */
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[20] = 1, /* TCH/F: a=13 / h=20 */
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[3] = 1, /* TCH/F: a=21 / h=3 (21+7=28, 25 is idle -> 29. 29%26=3) */
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};
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int rx_tchf_fn(struct l1sched_lchan_state *lchan,
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uint32_t fn, uint8_t bid, const sbit_t *bits,
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const struct l1sched_meas_set *meas)
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{
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int n_errors = -1, n_bits_total = 0, rc;
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sbit_t *buffer, *offset;
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uint8_t l2[128], *mask;
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size_t l2_len;
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int amr = 0;
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uint8_t ft;
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bool amr_is_cmr;
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/* Set up pointers */
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mask = &lchan->rx_burst_mask;
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buffer = lchan->rx_bursts;
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LOGP_LCHAND(lchan, LOGL_DEBUG, "Traffic received: fn=%u bid=%u\n", fn, bid);
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/* Align to the first burst of a block */
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if (*mask == 0x00 && bid != 0)
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return 0;
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/* Update mask */
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*mask |= (1 << bid);
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/* Store the measurements */
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l1sched_lchan_meas_push(lchan, meas);
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/* Copy burst to end of buffer of 8 bursts */
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offset = buffer + bid * 116 + 464;
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memcpy(offset, bits + 3, 58);
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memcpy(offset + 58, bits + 87, 58);
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/* Wait until complete set of bursts */
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if (bid != 3)
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return 0;
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/* Calculate AVG of the measurements */
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l1sched_lchan_meas_avg(lchan, 8);
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/* Check for complete set of bursts */
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if ((*mask & 0xff) != 0xff) {
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LOGP_LCHAND(lchan, LOGL_ERROR,
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"Received incomplete (%s) traffic frame at fn=%u (%u/%u)\n",
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l1sched_burst_mask2str(mask, 8), lchan->meas_avg.fn,
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lchan->meas_avg.fn % lchan->ts->mf_layout->period,
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lchan->ts->mf_layout->period);
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/* NOTE: do not abort here, give it a try. Maybe we're lucky ;) */
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}
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/* Keep the mask updated */
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*mask = *mask << 4;
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switch (lchan->tch_mode) {
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case GSM48_CMODE_SIGN:
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case GSM48_CMODE_SPEECH_V1: /* FR */
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rc = gsm0503_tch_fr_decode(l2, buffer,
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1, 0, &n_errors, &n_bits_total);
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break;
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case GSM48_CMODE_SPEECH_EFR: /* EFR */
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rc = gsm0503_tch_fr_decode(l2, buffer,
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1, 1, &n_errors, &n_bits_total);
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break;
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case GSM48_CMODE_SPEECH_AMR: /* AMR */
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/* the first FN 4,13,21 defines that CMI is included in frame,
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* the first FN 0,8,17 defines that CMR/CMC is included in frame.
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* NOTE: A frame ends 7 FN after start.
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*/
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amr_is_cmr = !sched_tchf_dl_amr_cmi_map[fn % 26];
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/* we store tch_data + 2 header bytes, the amr variable set to
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* 2 will allow us to skip the first 2 bytes in case we did
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* receive an FACCH frame instead of a voice frame (we do not
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* know this before we actually decode the frame) */
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amr = 2;
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rc = gsm0503_tch_afs_decode_dtx(l2 + amr, buffer,
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amr_is_cmr, lchan->amr.codec, lchan->amr.codecs, &lchan->amr.dl_ft,
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&lchan->amr.dl_cmr, &n_errors, &n_bits_total, &lchan->amr.last_dtx);
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/* only good speech frames get rtp header */
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if (rc != GSM_MACBLOCK_LEN && rc >= 4) {
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if (lchan->amr.last_dtx == AMR_OTHER) {
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ft = lchan->amr.codec[lchan->amr.dl_ft];
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} else {
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/* SID frames will always get Frame Type Index 8 (AMR_SID) */
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ft = AMR_SID;
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}
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rc = osmo_amr_rtp_enc(l2,
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lchan->amr.codec[lchan->amr.dl_cmr],
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ft, AMR_GOOD);
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if (rc < 0)
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LOGP_LCHAND(lchan, LOGL_ERROR,
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"osmo_amr_rtp_enc() returned rc=%d\n", rc);
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}
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break;
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default:
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LOGP_LCHAND(lchan, LOGL_ERROR, "Invalid TCH mode: %u\n", lchan->tch_mode);
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return -EINVAL;
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}
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/* Shift buffer by 4 bursts for interleaving */
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memcpy(buffer, buffer + 464, 464);
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/* Check decoding result */
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if (rc < 4) {
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LOGP_LCHAND(lchan, LOGL_ERROR,
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"Received bad frame (rc=%d, ber=%d/%d) at fn=%u\n",
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rc, n_errors, n_bits_total, lchan->meas_avg.fn);
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/* Send BFI */
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goto bfi;
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} else if (rc == GSM_MACBLOCK_LEN) {
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/* FACCH received, forward it to the higher layers */
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l1sched_handle_data_ind(lchan, l2 + amr, GSM_MACBLOCK_LEN,
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n_errors, n_bits_total,
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L1SCHED_DT_SIGNALING);
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/* Send BFI substituting a stolen TCH frame */
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n_errors = -1; /* ensure fake measurements */
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goto bfi;
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} else {
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/* A good TCH frame received */
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l2_len = rc;
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}
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/* Send a traffic frame to the higher layers */
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return l1sched_handle_data_ind(lchan, l2, l2_len, n_errors, n_bits_total, L1SCHED_DT_TRAFFIC);
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bfi:
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/* Didn't try to decode, fake measurements */
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if (n_errors < 0) {
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lchan->meas_avg = (struct l1sched_meas_set) {
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.fn = lchan->meas_avg.fn,
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.toa256 = 0,
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.rssi = -110,
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};
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/* No bursts => no errors */
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n_errors = 0;
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}
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/* BFI is not applicable in signalling mode */
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if (lchan->tch_mode == GSM48_CMODE_SIGN) {
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return l1sched_handle_data_ind(lchan, NULL, 0,
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n_errors, n_bits_total,
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L1SCHED_DT_TRAFFIC);
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}
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/* Bad frame indication */
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l2_len = l1sched_bad_frame_ind(l2, lchan);
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/* Send a BFI frame to the higher layers */
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return l1sched_handle_data_ind(lchan, l2, l2_len,
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n_errors, n_bits_total,
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L1SCHED_DT_TRAFFIC);
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}
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int tx_tchf_fn(struct l1sched_lchan_state *lchan,
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struct l1sched_burst_req *br)
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{
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ubit_t *buffer, *offset;
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const uint8_t *tsc;
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uint8_t *mask;
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size_t l2_len;
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int rc;
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/* Set up pointers */
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mask = &lchan->tx_burst_mask;
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buffer = lchan->tx_bursts;
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/* If we have encoded bursts */
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if (*mask)
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goto send_burst;
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/* Wait until a first burst in period */
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if (br->bid > 0)
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return 0;
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/* Shift buffer by 4 bursts back for interleaving */
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memcpy(buffer, buffer + 464, 464);
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/* populate the buffer with bursts */
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if (L1SCHED_PRIM_IS_FACCH(lchan->prim)) {
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/* Encode payload */
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rc = gsm0503_tch_fr_encode(buffer, lchan->prim->payload, GSM_MACBLOCK_LEN, 1);
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} else if (lchan->tch_mode == GSM48_CMODE_SPEECH_AMR) {
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int len;
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uint8_t cmr_codec;
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int ft, cmr, i;
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enum osmo_amr_type ft_codec;
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enum osmo_amr_quality bfi;
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int8_t sti, cmi;
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bool amr_fn_is_cmr;
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/* the first FN 0,8,17 defines that CMI is included in frame,
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* the first FN 4,13,21 defines that CMR is included in frame.
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*/
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amr_fn_is_cmr = !ul_amr_fn_is_cmi(br->fn);
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len = osmo_amr_rtp_dec(lchan->prim->payload, lchan->prim->payload_len,
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&cmr_codec, &cmi, &ft_codec,
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&bfi, &sti);
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if (len < 0) {
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LOGP_LCHAND(lchan, LOGL_ERROR, "Cannot send invalid AMR payload (%zu): %s\n",
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lchan->prim->payload_len, osmo_hexdump(lchan->prim->payload, lchan->prim->payload_len));
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goto free_bad_msg;
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}
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ft = -1;
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cmr = -1;
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for (i = 0; i < lchan->amr.codecs; i++) {
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if (lchan->amr.codec[i] == ft_codec)
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ft = i;
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if (lchan->amr.codec[i] == cmr_codec)
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cmr = i;
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}
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if (ft < 0) {
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LOGP_LCHAND(lchan, LOGL_ERROR,
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"Codec (FT = %d) of RTP frame not in list\n", ft_codec);
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goto free_bad_msg;
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}
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if (amr_fn_is_cmr && lchan->amr.ul_ft != ft) {
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LOGP_LCHAND(lchan, LOGL_ERROR,
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"Codec (FT = %d) of RTP cannot be changed now, but in next frame\n",
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ft_codec);
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goto free_bad_msg;
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}
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lchan->amr.ul_ft = ft;
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if (cmr < 0) {
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LOGP_LCHAND(lchan, LOGL_ERROR,
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"Codec (CMR = %d) of RTP frame not in list\n", cmr_codec);
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} else {
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lchan->amr.ul_cmr = cmr;
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}
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rc = gsm0503_tch_afs_encode(buffer, lchan->prim->payload + 2,
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lchan->prim->payload_len - 2, amr_fn_is_cmr,
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lchan->amr.codec, lchan->amr.codecs,
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lchan->amr.ul_ft,
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lchan->amr.ul_cmr);
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} else {
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/* Determine and check the payload length */
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switch (lchan->tch_mode) {
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case GSM48_CMODE_SIGN:
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case GSM48_CMODE_SPEECH_V1: /* FR */
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l2_len = GSM_FR_BYTES;
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break;
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case GSM48_CMODE_SPEECH_EFR: /* EFR */
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l2_len = GSM_EFR_BYTES;
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break;
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default:
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LOGP_LCHAND(lchan, LOGL_ERROR,
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"Invalid TCH mode: %u, dropping frame...\n",
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lchan->tch_mode);
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/* Forget this primitive */
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l1sched_prim_drop(lchan);
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return -EINVAL;
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}
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if (lchan->prim->payload_len != l2_len) {
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LOGP_LCHAND(lchan, LOGL_ERROR, "Primitive has odd length %zu "
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"(expected %zu for TCH or %u for FACCH), so dropping...\n",
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lchan->prim->payload_len, l2_len, GSM_MACBLOCK_LEN);
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l1sched_prim_drop(lchan);
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return -EINVAL;
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}
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rc = gsm0503_tch_fr_encode(buffer, lchan->prim->payload, l2_len, 1);
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}
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if (rc) {
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LOGP_LCHAND(lchan, LOGL_ERROR, "Failed to encode L2 payload (len=%zu): %s\n",
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lchan->prim->payload_len, osmo_hexdump(lchan->prim->payload,
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lchan->prim->payload_len));
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free_bad_msg:
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/* Forget this primitive */
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l1sched_prim_drop(lchan);
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return -EINVAL;
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}
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send_burst:
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/* Determine which burst should be sent */
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offset = buffer + br->bid * 116;
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/* Update mask */
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*mask |= (1 << br->bid);
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/* Choose proper TSC */
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tsc = l1sched_nb_training_bits[lchan->tsc];
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/* Compose a new burst */
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memset(br->burst, 0, 3); /* TB */
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memcpy(br->burst + 3, offset, 58); /* Payload 1/2 */
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memcpy(br->burst + 61, tsc, 26); /* TSC */
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memcpy(br->burst + 87, offset + 58, 58); /* Payload 2/2 */
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memset(br->burst + 145, 0, 3); /* TB */
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br->burst_len = GSM_BURST_LEN;
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LOGP_LCHAND(lchan, LOGL_DEBUG, "Scheduled fn=%u burst=%u\n", br->fn, br->bid);
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/* If we have sent the last (4/4) burst */
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if (*mask == 0x0f) {
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/* Confirm data / traffic sending */
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enum l1sched_data_type dt = L1SCHED_PRIM_IS_TCH(lchan->prim) ?
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L1SCHED_DT_TRAFFIC : L1SCHED_DT_SIGNALING;
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l1sched_handle_data_cnf(lchan, br->fn, dt);
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/* Forget processed primitive */
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l1sched_prim_drop(lchan);
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/* Reset mask */
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*mask = 0x00;
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}
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return 0;
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}
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