179 lines
4.7 KiB
C
179 lines
4.7 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) 2018-2022 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/gsm_utils.h>
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#include <osmocom/gsm/protocol/gsm_04_08.h>
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#include <osmocom/coding/gsm0503_coding.h>
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#include <osmocom/bb/trxcon/l1sched.h>
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#include <osmocom/bb/trxcon/logging.h>
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int rx_pdtch_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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const struct l1sched_lchan_desc *lchan_desc;
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uint8_t l2[GPRS_L2_MAX_LEN], *mask;
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int n_errors, n_bits_total, rc;
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sbit_t *buffer, *offset;
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size_t l2_len;
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/* Set up pointers */
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lchan_desc = &l1sched_lchan_desc[lchan->type];
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mask = &lchan->rx_burst_mask;
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buffer = lchan->rx_bursts;
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LOGP(DSCHD, LOGL_DEBUG, "Packet data received on %s: "
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"fn=%u ts=%u bid=%u\n", lchan_desc->name, fn, lchan->ts->index, 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 buffer of 4 bursts */
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offset = buffer + bid * 116;
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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, 4);
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/* Check for complete set of bursts */
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if ((*mask & 0xf) != 0xf) {
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LOGP(DSCHD, LOGL_ERROR, "Received incomplete (%s) data frame at "
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"fn=%u (%u/%u) for %s\n",
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l1sched_burst_mask2str(mask, 4), 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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lchan_desc->name);
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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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/* Attempt to decode */
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rc = gsm0503_pdtch_decode(l2, buffer,
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NULL, &n_errors, &n_bits_total);
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if (rc < 0) {
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LOGP(DSCHD, LOGL_ERROR, "Received bad %s frame (rc=%d, ber=%d/%d) at fn=%u\n",
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lchan_desc->name, rc, n_errors, n_bits_total, lchan->meas_avg.fn);
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}
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/* Determine L2 length */
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l2_len = rc > 0 ? rc : 0;
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/* Send a L2 frame to the higher layers */
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l1sched_handle_data_ind(lchan, l2, l2_len, n_errors, n_bits_total, L1SCHED_DT_PACKET_DATA);
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return 0;
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}
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int tx_pdtch_fn(struct l1sched_lchan_state *lchan,
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struct l1sched_burst_req *br)
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{
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const struct l1sched_lchan_desc *lchan_desc;
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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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int rc;
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/* Set up pointers */
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lchan_desc = &l1sched_lchan_desc[lchan->type];
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mask = &lchan->tx_burst_mask;
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buffer = lchan->tx_bursts;
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if (br->bid > 0) {
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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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else
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return 0;
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}
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/* Encode payload */
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rc = gsm0503_pdtch_encode(buffer, lchan->prim->payload,
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lchan->prim->payload_len);
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if (rc < 0) {
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LOGP(DSCHD, 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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/* 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(DSCHD, LOGL_DEBUG, "Scheduled %s fn=%u ts=%u burst=%u\n",
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lchan_desc->name, br->fn, lchan->ts->index, br->bid);
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/* If we have sent the last (4/4) burst */
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if ((*mask & 0x0f) == 0x0f) {
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/* Confirm data / traffic sending */
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l1sched_handle_data_cnf(lchan, br->fn, L1SCHED_DT_PACKET_DATA);
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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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