130 lines
3.3 KiB
C
130 lines
3.3 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 by Vadim Yanitskiy <axilirator@gmail.com>
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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 <talloc.h>
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#include <stdint.h>
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#include <arpa/inet.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/gsm_utils.h>
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#include <osmocom/coding/gsm0503_coding.h>
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#include "l1ctl_proto.h"
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#include "scheduler.h"
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#include "sched_trx.h"
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#include "logging.h"
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#include "trx_if.h"
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#include "l1ctl.h"
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static void decode_sb(struct gsm_time *time, uint8_t *bsic, uint8_t *sb_info)
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{
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uint8_t t3p;
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uint32_t sb;
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sb = ((uint32_t)sb_info[3] << 24)
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| (sb_info[2] << 16)
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| (sb_info[1] << 8)
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| sb_info[0];
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*bsic = (sb >> 2) & 0x3f;
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/* TS 05.02 Chapter 3.3.2.2.1 SCH Frame Numbers */
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time->t1 = ((sb >> 23) & 0x01)
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| ((sb >> 7) & 0x1fe)
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| ((sb << 9) & 0x600);
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time->t2 = (sb >> 18) & 0x1f;
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t3p = ((sb >> 24) & 0x01) | ((sb >> 15) & 0x06);
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time->t3 = t3p * 10 + 1;
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/* TS 05.02 Chapter 4.3.3 TDMA frame number */
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time->fn = gsm_gsmtime2fn(time);
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}
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int rx_sch_fn(struct trx_instance *trx, struct trx_ts *ts,
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struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
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const sbit_t *bits, const struct trx_meas_set *meas)
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{
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sbit_t payload[2 * 39];
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struct gsm_time time;
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uint8_t sb_info[4];
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uint8_t bsic;
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int rc;
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/* Obtain payload from burst */
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memcpy(payload, bits + 3, 39);
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memcpy(payload + 39, bits + 3 + 39 + 64, 39);
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/* Attempt to decode */
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rc = gsm0503_sch_decode(sb_info, payload);
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if (rc) {
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LOGP(DSCHD, LOGL_ERROR, "Received bad SCH burst at fn=%u\n", fn);
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return rc;
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}
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/* Decode BSIC and TDMA frame number */
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decode_sb(&time, &bsic, sb_info);
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LOGP(DSCHD, LOGL_DEBUG, "Received SCH: bsic=%u, fn=%u, sched_fn=%u\n",
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bsic, time.fn, trx->sched.fn_counter_proc);
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/* Check if decoded frame number matches */
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if (time.fn != fn) {
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LOGP(DSCHD, LOGL_ERROR, "Decoded fn=%u does not match "
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"fn=%u provided by scheduler\n", time.fn, fn);
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return -EINVAL;
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}
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/* We don't need to send L1CTL_FBSB_CONF */
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if (trx->l1l->fbsb_conf_sent)
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return 0;
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/* Send L1CTL_FBSB_CONF to higher layers */
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struct l1ctl_info_dl *data;
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data = talloc_zero_size(ts, sizeof(struct l1ctl_info_dl));
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if (data == NULL)
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return -ENOMEM;
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/* Fill in some downlink info */
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data->chan_nr = trx_lchan_desc[lchan->type].chan_nr | ts->index;
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data->link_id = trx_lchan_desc[lchan->type].link_id;
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data->band_arfcn = htons(trx->band_arfcn);
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data->frame_nr = htonl(fn);
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data->rx_level = -(meas->rssi);
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/* FIXME: set proper values */
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data->num_biterr = 0;
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data->fire_crc = 0;
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data->snr = 0;
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l1ctl_tx_fbsb_conf(trx->l1l, 0, data, bsic);
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/* Update BSIC value of trx_instance */
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trx->bsic = bsic;
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return 0;
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}
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