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/*
* (C) 2013 by Andreas Eversberg <jolly@eversberg.eu>
* (C) 2015-2017 by Harald Welte <laforge@gnumonks.org>
* Contributions by sysmocom - s.f.m.c. GmbH
*
* 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 <stdint.h>
#include <errno.h>
#include <osmocom/core/bits.h>
#include <osmocom/core/utils.h>
#include <osmocom/coding/gsm0503_coding.h>
#include <osmo-bts/bts.h>
#include <osmo-bts/l1sap.h>
#include <osmo-bts/logging.h>
#include <osmo-bts/scheduler.h>
#include <osmo-bts/scheduler_backend.h>
#include <sched_utils.h>
/* Add two arrays of sbits */
static void add_sbits(sbit_t * current, const sbit_t * previous)
{
unsigned int i;
for (i = 0; i < 464; i++) {
*current = (*current) / 2 + (*previous) / 2;
current++;
previous++;
}
}
/*! \brief a single (SDCCH/SACCH) burst was received by the PHY, process it */
int rx_data_fn(struct l1sched_ts *l1ts, const struct trx_ul_burst_ind *bi)
{
struct l1sched_chan_state *chan_state = &l1ts->chan_state[bi->chan];
sbit_t *burst, **bursts_p = &chan_state->ul_bursts;
uint32_t *first_fn = &chan_state->ul_first_fn;
uint8_t *mask = &chan_state->ul_mask;
uint8_t l2[GSM_MACBLOCK_LEN], l2_len;
struct l1sched_meas_set meas_avg;
int n_errors = 0;
int n_bits_total = 0;
uint16_t ber10k;
int rc;
struct gsm_lchan *lchan = chan_state->lchan;
bool rep_sacch = L1SAP_IS_LINK_SACCH(trx_chan_desc[bi->chan].link_id) && lchan->repeated_ul_sacch_active;
/* If handover RACH detection is turned on, treat this burst as an Access Burst.
* Handle NOPE.ind as usually to ensure proper Uplink measurement reporting. */
if (chan_state->ho_rach_detect == 1 && ~bi->flags & TRX_BI_F_NOPE_IND)
return rx_rach_fn(l1ts, bi);
LOGL1SB(DL1P, LOGL_DEBUG, l1ts, bi, "Received Data, bid=%u\n", bi->bid);
/* allocate burst memory, if not already */
if (!*bursts_p) {
*bursts_p = talloc_zero_size(tall_bts_ctx, 464);
if (!*bursts_p)
return -ENOMEM;
}
/* UL-SACCH requires additional memory to keep a copy of each previous
* burst set. */
if (L1SAP_IS_LINK_SACCH(trx_chan_desc[bi->chan].link_id) && !chan_state->ul_bursts_prev) {
chan_state->ul_bursts_prev = talloc_zero_size(tall_bts_ctx, 464);
if (!chan_state->ul_bursts_prev)
return -ENOMEM;
}
/* clear burst & store frame number of first burst */
if (bi->bid == 0) {
memset(*bursts_p, 0, 464);
*mask = 0x0;
*first_fn = bi->fn;
}
/* update mask */
*mask |= (1 << bi->bid);
/* store measurements */
trx_sched_meas_push(chan_state, bi);
/* Copy burst to buffer of 4 bursts. If the burst indication contains
* no data, ensure that the buffer does not stay uninitialized */
burst = *bursts_p + bi->bid * 116;
if (bi->burst_len > 0) {
memcpy(burst, bi->burst + 3, 58);
memcpy(burst + 58, bi->burst + 87, 58);
} else
memset(burst, 0, 58 * 2);
/* wait until complete set of bursts */
if (bi->bid != 3)
return 0;
/* average measurements of the last 4 bursts */
trx_sched_meas_avg(chan_state, &meas_avg, SCHED_MEAS_AVG_M_QUAD);
/* check for complete set of bursts */
if ((*mask & 0xf) != 0xf) {
LOGL1SB(DL1P, LOGL_NOTICE, l1ts, bi, "Received incomplete data (%u/%u)\n",
bi->fn % l1ts->mf_period, l1ts->mf_period);
/* we require first burst to have correct FN */
if (!(*mask & 0x1)) {
*mask = 0x0;
return 0;
}
}
*mask = 0x0;
/* decode */
rc = gsm0503_xcch_decode(l2, *bursts_p, &n_errors, &n_bits_total);
if (rc) {
LOGL1SB(DL1P, LOGL_NOTICE, l1ts, bi, "Received bad data (%u/%u)\n",
bi->fn % l1ts->mf_period, l1ts->mf_period);
l2_len = 0;
/* When SACCH Repetition is active, we may try to decode the
* current SACCH block by including the information from the
* information from the previous SACCH block. See also:
* 3GPP TS 44.006, section 11.2 */
if (rep_sacch) {
add_sbits(*bursts_p, chan_state->ul_bursts_prev);
rc = gsm0503_xcch_decode(l2, *bursts_p, &n_errors, &n_bits_total);
if (rc) {
LOGL1SB(DL1P, LOGL_NOTICE, l1ts, bi,
"Combining current SACCH block with previous SACCH block also yields bad data (%u/%u)\n",
bi->fn % l1ts->mf_period, l1ts->mf_period);
} else {
LOGL1SB(DL1P, LOGL_DEBUG, l1ts, bi,
"Combining current SACCH block with previous SACCH block yields good data (%u/%u)\n",
bi->fn % l1ts->mf_period, l1ts->mf_period);
l2_len = GSM_MACBLOCK_LEN;
}
}
} else
l2_len = GSM_MACBLOCK_LEN;
ber10k = compute_ber10k(n_bits_total, n_errors);
/* Keep a copy to ease decoding in the next repetition pass */
if (rep_sacch)
memcpy(chan_state->ul_bursts_prev, *bursts_p, 464);
return _sched_compose_ph_data_ind(l1ts, *first_fn,
bi->chan, l2, l2_len,
meas_avg.rssi, meas_avg.toa256,
meas_avg.ci_cb, ber10k,
PRES_INFO_UNKNOWN);
}
/* obtain a to-be-transmitted xCCH (e.g SACCH or SDCCH) burst */
int tx_data_fn(struct l1sched_ts *l1ts, struct trx_dl_burst_req *br)
{
struct msgb *msg = NULL; /* make GCC happy */
ubit_t *burst, **bursts_p = &l1ts->chan_state[br->chan].dl_bursts;
/* send burst, if we already got a frame */
if (br->bid > 0) {
if (!*bursts_p)
return 0;
goto send_burst;
}
/* get mac block from queue */
msg = _sched_dequeue_prim(l1ts, br);
if (msg)
goto got_msg;
LOGL1SB(DL1P, LOGL_INFO, l1ts, br, "No prim for transmit.\n");
no_msg:
/* free burst memory */
if (*bursts_p) {
talloc_free(*bursts_p);
*bursts_p = NULL;
}
return -ENODEV;
got_msg:
/* check validity of message */
if (msgb_l2len(msg) != GSM_MACBLOCK_LEN) {
LOGL1SB(DL1P, LOGL_FATAL, l1ts, br, "Prim has odd len=%u != %u\n",
msgb_l2len(msg), GSM_MACBLOCK_LEN);
/* free message */
msgb_free(msg);
goto no_msg;
}
/* BURST BYPASS */
/* handle loss detection of SACCH */
if (L1SAP_IS_LINK_SACCH(trx_chan_desc[br->chan].link_id)) {
/* count and send BFI */
if (++(l1ts->chan_state[br->chan].lost_frames) > 1) {
/* TODO: Should we pass old TOA here? Otherwise we risk
* unnecessary decreasing TA */
/* Note: RSSI is set to 0 to indicate to the higher
* layers that this is a faked ph_data_ind */
_sched_compose_ph_data_ind(l1ts, 0, br->chan, NULL, 0,
0, 0, 0, 10000,
PRES_INFO_INVALID);
}
}
/* allocate burst memory, if not already */
if (!*bursts_p) {
*bursts_p = talloc_zero_size(tall_bts_ctx, 464);
if (!*bursts_p)
return -ENOMEM;
}
/* encode bursts */
gsm0503_xcch_encode(*bursts_p, msg->l2h);
/* free message */
msgb_free(msg);
send_burst:
/* compose burst */
burst = *bursts_p + br->bid * 116;
memcpy(br->burst + 3, burst, 58);
memcpy(br->burst + 61, TRX_GMSK_NB_TSC(br), 26);
memcpy(br->burst + 87, burst + 58, 58);
br->burst_len = GSM_BURST_LEN;
LOGL1SB(DL1P, LOGL_DEBUG, l1ts, br, "Transmitting burst=%u.\n", br->bid);
return 0;
}
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