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/*
* OsmocomBB <-> SDR connection bridge
* TDMA scheduler: handlers for DL / UL bursts on logical channels
*
* (C) 2017 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 <stdbool.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/bits.h>
#include <osmocom/gsm/gsm_utils.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 "trxcon.h"
#include "l1ctl.h"
/**
* 41-bit RACH synchronization sequence
* GSM 05.02 Chapter 5.2.7 Access burst (AB)
*/
static ubit_t rach_synch_seq[] = {
0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1,
1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0,
1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0,
};
/* Obtain a to-be-transmitted RACH burst */
int tx_rach_fn(struct trx_instance *trx, struct trx_ts *ts,
struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid)
{
struct l1ctl_rach_req *req;
uint8_t burst[GSM_BURST_LEN];
uint8_t payload[36];
int rc;
/* Get the payload from a current primitive */
req = (struct l1ctl_rach_req *) lchan->prim->payload;
/* Delay RACH sending according to offset value */
if (req->offset-- > 0)
return 0;
/* Encode (8-bit) payload */
rc = gsm0503_rach_ext_encode(payload, req->ra, trx->bsic, false);
if (rc) {
LOGP(DSCHD, LOGL_ERROR, "Could not encode RACH burst\n");
/* Forget this primitive */
sched_prim_drop(lchan);
return rc;
}
/* Compose RACH burst */
memset(burst, 0, 8); /* TB */
memcpy(burst + 8, rach_synch_seq, 41); /* sync seq */
memcpy(burst + 49, payload, 36); /* payload */
memset(burst + 85, 0, 63); /* TB + GP */
LOGP(DSCHD, LOGL_DEBUG, "Transmitting RACH fn=%u\n", fn);
/* Forward burst to scheduler */
rc = sched_trx_handle_tx_burst(trx, ts, lchan, fn, burst);
if (rc) {
/* Forget this primitive */
sched_prim_drop(lchan);
return rc;
}
/* Confirm RACH request */
l1ctl_tx_rach_conf(trx->l1l, fn);
/* Forget processed primitive */
sched_prim_drop(lchan);
return 0;
}
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