212 lines
5.5 KiB
C
212 lines
5.5 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) 2017-2020 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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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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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 "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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int rx_data_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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const struct trx_lchan_desc *lchan_desc;
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uint8_t l2[GSM_MACBLOCK_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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/* Set up pointers */
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lchan_desc = &trx_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, "Data received on %s: fn=%u ts=%u bid=%u\n",
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lchan_desc->name, fn, 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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sched_trx_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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sched_trx_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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burst_mask2str(mask, 4), lchan->meas_avg.fn,
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lchan->meas_avg.fn % ts->mf_layout->period,
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ts->mf_layout->period,
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lchan_desc->name);
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/* NOTE: xCCH has an insane amount of redundancy for error
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* correction, so even just 2 valid bursts might be enough
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* to reconstruct some L2 frames. This is why we do not
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* abort here. */
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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_xcch_decode(l2, buffer, &n_errors, &n_bits_total);
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if (rc) {
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LOGP(DSCHD, LOGL_ERROR, "Received bad data frame at fn=%u "
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"(%u/%u) for %s\n", lchan->meas_avg.fn,
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lchan->meas_avg.fn % ts->mf_layout->period,
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ts->mf_layout->period,
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lchan_desc->name);
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/**
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* We should anyway send dummy frame for
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* proper measurement reporting...
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*/
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return sched_send_dt_ind(trx, ts, lchan, NULL, 0,
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n_errors, true, false);
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}
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/* Send a L2 frame to the higher layers */
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return sched_send_dt_ind(trx, ts, lchan, l2, GSM_MACBLOCK_LEN,
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n_errors, false, false);
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}
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int tx_data_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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{
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const struct trx_lchan_desc *lchan_desc;
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ubit_t burst[GSM_BURST_LEN];
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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 = &trx_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 (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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/* Check the prim payload length */
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if (lchan->prim->payload_len != GSM_MACBLOCK_LEN) {
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LOGP(DSCHD, LOGL_ERROR, "Primitive has odd length %zu (expected %u), "
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"so dropping...\n", lchan->prim->payload_len, GSM_MACBLOCK_LEN);
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sched_prim_drop(lchan);
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return -EINVAL;
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}
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/* Encode payload */
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rc = gsm0503_xcch_encode(buffer, lchan->prim->payload);
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if (rc) {
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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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sched_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 + bid * 116;
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/* Update mask */
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*mask |= (1 << bid);
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/* Choose proper TSC */
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tsc = sched_nb_training_bits[trx->tsc];
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/* Compose a new burst */
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memset(burst, 0, 3); /* TB */
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memcpy(burst + 3, offset, 58); /* Payload 1/2 */
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memcpy(burst + 61, tsc, 26); /* TSC */
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memcpy(burst + 87, offset + 58, 58); /* Payload 2/2 */
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memset(burst + 145, 0, 3); /* TB */
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LOGP(DSCHD, LOGL_DEBUG, "Transmitting %s fn=%u ts=%u burst=%u\n",
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lchan_desc->name, fn, ts->index, bid);
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/* Forward burst to scheduler */
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rc = sched_trx_handle_tx_burst(trx, ts, lchan, fn, burst);
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if (rc) {
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/* Forget this primitive */
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sched_prim_drop(lchan);
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/* Reset mask */
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*mask = 0x00;
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return rc;
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}
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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 sending */
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sched_send_dt_conf(trx, ts, lchan, fn, false);
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/* Forget processed primitive */
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sched_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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