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/*
* OsmocomBB <-> SDR connection bridge
* TDMA scheduler: handlers for DL / UL bursts on logical channels
*
* (C) 2017-2020 by Vadim Yanitskiy <axilirator@gmail.com>
*
* 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 <osmocom/core/logging.h>
#include <osmocom/core/bits.h>
#include <osmocom/gsm/gsm_utils.h>
#include <osmocom/gsm/protocol/gsm_04_08.h>
#include <osmocom/coding/gsm0503_coding.h>
#include "l1ctl_proto.h"
#include "scheduler.h"
#include "sched_trx.h"
#include "logging.h"
#include "trx_if.h"
#include "l1ctl.h"
int rx_data_fn(struct trx_instance *trx, struct trx_ts *ts,
struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
const sbit_t *bits, const struct trx_meas_set *meas)
{
const struct trx_lchan_desc *lchan_desc;
uint8_t l2[GSM_MACBLOCK_LEN], *mask;
int n_errors, n_bits_total, rc;
sbit_t *buffer, *offset;
/* Set up pointers */
lchan_desc = &trx_lchan_desc[lchan->type];
mask = &lchan->rx_burst_mask;
buffer = lchan->rx_bursts;
LOGP(DSCHD, LOGL_DEBUG, "Data received on %s: fn=%u ts=%u bid=%u\n",
lchan_desc->name, fn, ts->index, bid);
/* Align to the first burst of a block */
if (*mask == 0x00 && bid != 0)
return 0;
/* Update mask */
*mask |= (1 << bid);
/* Store the measurements */
sched_trx_meas_push(lchan, meas);
/* Copy burst to buffer of 4 bursts */
offset = buffer + bid * 116;
memcpy(offset, bits + 3, 58);
memcpy(offset + 58, bits + 87, 58);
/* Wait until complete set of bursts */
if (bid != 3)
return 0;
/* Calculate AVG of the measurements */
sched_trx_meas_avg(lchan, 4);
/* Check for complete set of bursts */
if ((*mask & 0xf) != 0xf) {
LOGP(DSCHD, LOGL_ERROR, "Received incomplete (%s) data frame at "
"fn=%u (%u/%u) for %s\n",
burst_mask2str(mask, 4), lchan->meas_avg.fn,
lchan->meas_avg.fn % ts->mf_layout->period,
ts->mf_layout->period,
lchan_desc->name);
/* NOTE: xCCH has an insane amount of redundancy for error
* correction, so even just 2 valid bursts might be enough
* to reconstruct some L2 frames. This is why we do not
* abort here. */
}
/* Keep the mask updated */
*mask = *mask << 4;
/* Attempt to decode */
rc = gsm0503_xcch_decode(l2, buffer, &n_errors, &n_bits_total);
if (rc) {
LOGP(DSCHD, LOGL_ERROR, "Received bad data frame at fn=%u "
"(%u/%u) for %s\n", lchan->meas_avg.fn,
lchan->meas_avg.fn % ts->mf_layout->period,
ts->mf_layout->period,
lchan_desc->name);
/**
* We should anyway send dummy frame for
* proper measurement reporting...
*/
return sched_send_dt_ind(trx, ts, lchan, NULL, 0,
n_errors, true, false);
}
/* Send a L2 frame to the higher layers */
return sched_send_dt_ind(trx, ts, lchan, l2, GSM_MACBLOCK_LEN,
n_errors, false, false);
}
int tx_data_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;
int rc;
/* Set up pointers */
lchan_desc = &trx_lchan_desc[lchan->type];
mask = &lchan->tx_burst_mask;
buffer = lchan->tx_bursts;
if (bid > 0) {
/* If we have encoded bursts */
if (*mask)
goto send_burst;
else
return 0;
}
/* Check the prim payload length */
if (lchan->prim->payload_len != GSM_MACBLOCK_LEN) {
LOGP(DSCHD, LOGL_ERROR, "Primitive has odd length %zu (expected %u), "
"so dropping...\n", lchan->prim->payload_len, GSM_MACBLOCK_LEN);
sched_prim_drop(lchan);
return -EINVAL;
}
/* Encode payload */
rc = gsm0503_xcch_encode(buffer, lchan->prim->payload);
if (rc) {
LOGP(DSCHD, LOGL_ERROR, "Failed to encode L2 payload (len=%zu): %s\n",
lchan->prim->payload_len, osmo_hexdump(lchan->prim->payload,
lchan->prim->payload_len));
/* Forget this primitive */
sched_prim_drop(lchan);
return -EINVAL;
}
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 scheduler */
rc = sched_trx_handle_tx_burst(trx, ts, lchan, fn, burst);
if (rc) {
/* Forget this primitive */
sched_prim_drop(lchan);
/* Reset mask */
*mask = 0x00;
return rc;
}
/* If we have sent the last (4/4) burst */
if ((*mask & 0x0f) == 0x0f) {
/* Confirm data sending */
sched_send_dt_conf(trx, ts, lchan, fn, false);
/* Forget processed primitive */
sched_prim_drop(lchan);
/* Reset mask */
*mask = 0x00;
}
return 0;
}
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