diff options
Diffstat (limited to 'src/host/trxcon/src/sched_lchan_pdtch.c')
-rw-r--r-- | src/host/trxcon/src/sched_lchan_pdtch.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/src/host/trxcon/src/sched_lchan_pdtch.c b/src/host/trxcon/src/sched_lchan_pdtch.c new file mode 100644 index 00000000..5b884ddc --- /dev/null +++ b/src/host/trxcon/src/sched_lchan_pdtch.c @@ -0,0 +1,195 @@ +/* + * OsmocomBB <-> SDR connection bridge + * TDMA scheduler: handlers for DL / UL bursts on logical channels + * + * (C) 2018-2022 by Vadim Yanitskiy <axilirator@gmail.com> + * Contributions by sysmocom - s.f.m.c. GmbH + * + * 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. + * + */ + +#include <errno.h> +#include <string.h> +#include <stdint.h> + +#include <osmocom/core/logging.h> +#include <osmocom/core/bits.h> + +#include <osmocom/gsm/gsm0502.h> +#include <osmocom/gsm/gsm_utils.h> +#include <osmocom/gsm/protocol/gsm_04_08.h> +#include <osmocom/coding/gsm0503_coding.h> + +#include <osmocom/bb/l1sched/l1sched.h> +#include <osmocom/bb/l1sched/logging.h> + +int rx_pdtch_fn(struct l1sched_lchan_state *lchan, + const struct l1sched_burst_ind *bi) +{ + uint8_t l2[GPRS_L2_MAX_LEN]; + int n_errors, n_bits_total, rc; + sbit_t *bursts_p, *burst; + size_t l2_len; + uint32_t *mask; + + /* Set up pointers */ + mask = &lchan->rx_burst_mask; + bursts_p = lchan->rx_bursts; + + LOGP_LCHAND(lchan, LOGL_DEBUG, + "Packet data received: fn=%u bid=%u\n", bi->fn, bi->bid); + + /* Align to the first burst of a block */ + if (*mask == 0x00 && bi->bid != 0) + return 0; + + /* Update mask */ + *mask |= (1 << bi->bid); + + /* Store the measurements */ + l1sched_lchan_meas_push(lchan, bi); + + /* Copy burst to buffer of 4 bursts */ + burst = bursts_p + bi->bid * 116; + memcpy(burst, bi->burst + 3, 58); + memcpy(burst + 58, bi->burst + 87, 58); + + /* Wait until complete set of bursts */ + if (bi->bid != 3) + return 0; + + /* Calculate AVG of the measurements */ + l1sched_lchan_meas_avg(lchan, 4); + + /* Check for complete set of bursts */ + if ((*mask & 0xf) != 0xf) { + LOGP_LCHAND(lchan, LOGL_ERROR, + "Received incomplete (%s) packet data at fn=%u (%u/%u)\n", + l1sched_burst_mask2str(mask, 4), lchan->meas_avg.fn, + lchan->meas_avg.fn % lchan->ts->mf_layout->period, + lchan->ts->mf_layout->period); + /* NOTE: do not abort here, give it a try. Maybe we're lucky ;) */ + } + + /* Keep the mask updated */ + *mask = *mask << 4; + + /* Attempt to decode */ + rc = gsm0503_pdtch_decode(l2, bursts_p, + NULL, &n_errors, &n_bits_total); + if (rc < 0) { + LOGP_LCHAND(lchan, LOGL_ERROR, + "Received bad frame (rc=%d, ber=%d/%d) at fn=%u\n", + rc, n_errors, n_bits_total, lchan->meas_avg.fn); + } + + /* Determine L2 length */ + l2_len = rc > 0 ? rc : 0; + + /* Send a L2 frame to the higher layers */ + l1sched_lchan_emit_data_ind(lchan, l2, l2_len, n_errors, n_bits_total, true); + + return 0; +} + +static struct msgb *prim_dequeue_pdtch(struct l1sched_lchan_state *lchan, uint32_t fn) +{ + while (!llist_empty(&lchan->tx_prims)) { + struct msgb *msg = llist_first_entry(&lchan->tx_prims, struct msgb, list); + const struct l1sched_prim *prim = l1sched_prim_from_msgb(msg); + int ret = gsm0502_fncmp(prim->data_req.frame_nr, fn); + + if (OSMO_LIKELY(ret == 0)) { /* it's a match! */ + llist_del(&msg->list); + return msg; + } else if (ret > 0) { /* not now, come back later */ + break; + } /* else: the ship has sailed, drop your ticket */ + + LOGP_LCHAND(lchan, LOGL_ERROR, + "%s(): dropping stale Tx prim (current Fn=%u, prim Fn=%u): %s\n", + __func__, fn, prim->data_req.frame_nr, msgb_hexdump_l2(msg)); + llist_del(&msg->list); + msgb_free(msg); + } + + return NULL; +} + +int tx_pdtch_fn(struct l1sched_lchan_state *lchan, + struct l1sched_burst_req *br) +{ + ubit_t *bursts_p, *burst; + const uint8_t *tsc; + uint32_t *mask; + int rc; + + /* Set up pointers */ + mask = &lchan->tx_burst_mask; + bursts_p = lchan->tx_bursts; + + if (br->bid > 0) { + if ((*mask & 0x01) != 0x01) + return -ENOENT; + goto send_burst; + } + + *mask = *mask << 4; + + struct msgb *msg = prim_dequeue_pdtch(lchan, br->fn); + if (msg == NULL) + return -ENOENT; + + /* Encode payload */ + rc = gsm0503_pdtch_encode(bursts_p, msgb_l2(msg), msgb_l2len(msg)); + if (rc < 0) { + LOGP_LCHAND(lchan, LOGL_ERROR, "Failed to encode L2 payload (len=%u): %s\n", + msgb_l2len(msg), msgb_hexdump_l2(msg)); + msgb_free(msg); + return -EINVAL; + } + + /* Cache the prim, so that we can confirm it later (see below) */ + OSMO_ASSERT(lchan->prim == NULL); + lchan->prim = msg; + +send_burst: + /* Determine which burst should be sent */ + burst = bursts_p + br->bid * 116; + + /* Update mask */ + *mask |= (1 << br->bid); + + /* Choose proper TSC */ + tsc = l1sched_nb_training_bits[lchan->tsc]; + + /* Compose a new burst */ + memset(br->burst, 0, 3); /* TB */ + memcpy(br->burst + 3, burst, 58); /* Payload 1/2 */ + memcpy(br->burst + 61, tsc, 26); /* TSC */ + memcpy(br->burst + 87, burst + 58, 58); /* Payload 2/2 */ + memset(br->burst + 145, 0, 3); /* TB */ + br->burst_len = GSM_NBITS_NB_GMSK_BURST; + + LOGP_LCHAND(lchan, LOGL_DEBUG, "Scheduled at fn=%u burst=%u\n", br->fn, br->bid); + + if (br->bid == 3) { + /* Confirm data / traffic sending (pass ownership of the msgb/prim) */ + l1sched_lchan_emit_data_cnf(lchan, lchan->prim, + GSM_TDMA_FN_SUB(br->fn, 3)); + lchan->prim = NULL; + } + + return 0; +} |