Review at  https://gerrit.osmocom.org/6803

host/trxcon/scheduler: add initial TCH/F channel support

This change implements basic TCH/F lchan handlers for both data
reception and transmission. Only FACCH (signaling), FR and EFR
payloads are supported at the moment.

Change-Id: If6b0eaede2b484484d2a824e7219ff04483266a1
---
M src/host/trxcon/Makefile.am
M src/host/trxcon/sched_lchan_common.c
M src/host/trxcon/sched_lchan_desc.c
A src/host/trxcon/sched_lchan_tchf.c
M src/host/trxcon/sched_trx.h
5 files changed, 386 insertions(+), 2 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmocom-bb refs/changes/03/6803/1

diff --git a/src/host/trxcon/Makefile.am b/src/host/trxcon/Makefile.am
index 90c7a3c..88ff2be 100644
--- a/src/host/trxcon/Makefile.am
+++ b/src/host/trxcon/Makefile.am
@@ -34,6 +34,7 @@
        sched_lchan_common.c \
        sched_lchan_desc.c \
        sched_lchan_xcch.c \
+       sched_lchan_tchf.c \
        sched_lchan_rach.c \
        sched_lchan_sch.c \
        sched_mframe.c \
diff --git a/src/host/trxcon/sched_lchan_common.c 
b/src/host/trxcon/sched_lchan_common.c
index 925a441..6d75533 100644
--- a/src/host/trxcon/sched_lchan_common.c
+++ b/src/host/trxcon/sched_lchan_common.c
@@ -33,6 +33,7 @@
 #include <osmocom/core/bits.h>
 
 #include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/protocol/gsm_08_58.h>
 
 #include "l1ctl_proto.h"
 #include "scheduler.h"
@@ -145,3 +146,82 @@
 
        return 0;
 }
+
+/**
+ * Composes a bad frame indication message
+ * according to the current tch_mode.
+ *
+ * @param  l2       Pointer to allocated byte array
+ * @param  tch_mode Current TCH mode
+ * @return          How much bytes were written
+ */
+size_t sched_bad_frame_ind(uint8_t *l2, uint8_t rsl_cmode, uint8_t tch_mode)
+{
+       /* BFI is only required for speech */
+       if (rsl_cmode != RSL_CMOD_SPD_SPEECH)
+               return 0;
+
+       switch (tch_mode) {
+       case GSM48_CMODE_SIGN:
+       case GSM48_CMODE_SPEECH_V1: /* Full Rate */
+               memset(l2, 0x00, GSM_FR_BYTES);
+               l2[0] = 0xd0;
+               return GSM_FR_BYTES;
+       case GSM48_CMODE_SPEECH_EFR: /* Enhanced Full Rate */
+               memset(l2, 0x00, GSM_EFR_BYTES);
+               l2[0] = 0xc0;
+               return GSM_EFR_BYTES;
+       case GSM48_CMODE_SPEECH_AMR: /* Adaptive Multi Rate */
+               /* FIXME: AMR is not implemented yet */
+               return 0;
+       default:
+               LOGP(DSCH, LOGL_ERROR, "Invalid TCH mode: %u\n", tch_mode);
+               return 0;
+       }
+}
+
+#define PRIM_IS_FACCH(prim) \
+       prim->payload_len == GSM_MACBLOCK_LEN
+
+#define PRIM_IS_TCH(prim) \
+       prim->payload_len != GSM_MACBLOCK_LEN
+
+struct trx_ts_prim *sched_dequeue_tch_prim(struct llist_head *queue)
+{
+       struct trx_ts_prim *a, *b;
+
+       /* Obtain the first prim from TX queue */
+       a = llist_entry(queue->next, struct trx_ts_prim, list);
+
+       /* If this is the only one => do nothing... */
+       if (queue->next->next == queue)
+               return a;
+
+       /* Obtain the second prim from TX queue */
+       b = llist_entry(queue->next->next, struct trx_ts_prim, list);
+
+       /* Find and prioritize FACCH  */
+       if (PRIM_IS_FACCH(a) && PRIM_IS_TCH(b)) {
+               /**
+                * Case 1: first is FACCH, second is TCH:
+                * Prioritize FACCH, dropping TCH
+                */
+               llist_del(&b->list);
+               talloc_free(b);
+               return a;
+       } else if (PRIM_IS_TCH(a) && PRIM_IS_FACCH(b)) {
+               /**
+                * Case 2: first is TCH, second is FACCH:
+                * Prioritize FACCH, dropping TCH
+                */
+               llist_del(&a->list);
+               talloc_free(a);
+               return b;
+       } else {
+               /**
+                * Otherwise: both are TCH or FACCH frames:
+                * Nothing to prioritize, return the first one
+                */
+               return a;
+       }
+}
diff --git a/src/host/trxcon/sched_lchan_desc.c 
b/src/host/trxcon/sched_lchan_desc.c
index c483db8..390b1ef 100644
--- a/src/host/trxcon/sched_lchan_desc.c
+++ b/src/host/trxcon/sched_lchan_desc.c
@@ -30,11 +30,9 @@
 
 /* TODO: implement */
 #define tx_pdtch_fn    NULL
-#define tx_tchf_fn     NULL
 #define tx_tchh_fn     NULL
 
 #define rx_pdtch_fn    NULL
-#define rx_tchf_fn     NULL
 #define rx_tchh_fn     NULL
 
 /* Forward declaration of handlers */
@@ -52,6 +50,13 @@
 int tx_rach_fn(struct trx_instance *trx, struct trx_ts *ts,
        struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid);
 
+int rx_tchf_fn(struct trx_instance *trx, struct trx_ts *ts,
+       struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
+       sbit_t *bits, int8_t rssi, float toa);
+
+int tx_tchf_fn(struct trx_instance *trx, struct trx_ts *ts,
+       struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid);
+
 const struct trx_lchan_desc trx_lchan_desc[_TRX_CHAN_MAX] = {
        {
                TRXC_IDLE,              "IDLE",
diff --git a/src/host/trxcon/sched_lchan_tchf.c 
b/src/host/trxcon/sched_lchan_tchf.c
new file mode 100644
index 0000000..237e538
--- /dev/null
+++ b/src/host/trxcon/sched_lchan_tchf.c
@@ -0,0 +1,292 @@
+/*
+ * OsmocomBB <-> SDR connection bridge
+ * TDMA scheduler: handlers for DL / UL bursts on logical channels
+ *
+ * (C) 2017 by Vadim Yanitskiy <axilira...@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 <talloc.h>
+#include <stdint.h>
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/bits.h>
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/protocol/gsm_08_58.h>
+#include <osmocom/gsm/gsm_utils.h>
+
+#include <osmocom/coding/gsm0503_coding.h>
+#include <osmocom/codec/codec.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"
+
+int rx_tchf_fn(struct trx_instance *trx, struct trx_ts *ts,
+       struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
+       sbit_t *bits, int8_t rssi, float toa)
+{
+       const struct trx_lchan_desc *lchan_desc;
+       uint8_t rsl_cmode, tch_mode, mode;
+       int n_errors, n_bits_total, rc;
+       sbit_t *buffer, *offset;
+       uint8_t l2[128], *mask;
+       uint32_t *first_fn;
+       size_t l2_len;
+
+       /* Set up pointers */
+       lchan_desc = &trx_lchan_desc[lchan->type];
+       first_fn = &lchan->rx_first_fn;
+       mask = &lchan->rx_burst_mask;
+       buffer = lchan->rx_bursts;
+
+       LOGP(DSCHD, LOGL_DEBUG, "Traffic received on %s: fn=%u ts=%u bid=%u\n",
+               lchan_desc->name, fn, ts->index, bid);
+
+       /* Reset internal state */
+       if (bid == 0) {
+               /* Clean up old measurements */
+               memset(&lchan->meas, 0x00, sizeof(lchan->meas));
+
+               *first_fn = fn;
+               *mask = 0x00;
+       }
+
+       /* Update mask */
+       *mask |= (1 << bid);
+
+       /* Update mask and RSSI */
+       lchan->meas.rssi_sum += rssi;
+       lchan->meas.toa_sum += toa;
+       lchan->meas.rssi_num++;
+       lchan->meas.toa_num++;
+
+       /* Copy burst to end of buffer of 8 bursts */
+       offset = buffer + bid * 116 + 464;
+       memcpy(offset, bits + 3, 58);
+       memcpy(offset + 58, bits + 87, 58);
+
+       /* Wait until complete set of bursts */
+       if (bid != 3)
+               return 0;
+
+       /* Check for complete set of bursts */
+       if ((*mask & 0xf) != 0xf) {
+               LOGP(DSCHD, LOGL_DEBUG, "Received incomplete traffic frame at "
+                       "fn=%u (%u/%u) for %s\n", *first_fn,
+                       (*first_fn) % ts->mf_layout->period,
+                       ts->mf_layout->period,
+                       lchan_desc->name);
+               return -EINVAL;
+       }
+
+       /**
+        * Get current RSL / TCH modes
+        *
+        * FIXME: we do support speech only, and
+        * CSD support may be implemented latter.
+        */
+       rsl_cmode = RSL_CMOD_SPD_SPEECH;
+       tch_mode = lchan->tch_mode;
+
+       mode = rsl_cmode != RSL_CMOD_SPD_SPEECH ?
+               GSM48_CMODE_SPEECH_V1 : tch_mode;
+
+       switch (mode) {
+       case GSM48_CMODE_SIGN:
+       case GSM48_CMODE_SPEECH_V1: /* FR */
+               rc = gsm0503_tch_fr_decode(l2, buffer,
+                       1, 0, &n_errors, &n_bits_total);
+               break;
+       case GSM48_CMODE_SPEECH_EFR: /* EFR */
+               rc = gsm0503_tch_fr_decode(l2, buffer,
+                       1, 1, &n_errors, &n_bits_total);
+               break;
+       case GSM48_CMODE_SPEECH_AMR: /* AMR */
+               /**
+                * TODO: AMR requires a dedicated loop,
+                * which will be implemented later...
+                */
+               LOGP(DSCHD, LOGL_ERROR, "AMR isn't supported yet\n");
+               return -ENOTSUP;
+       default:
+               LOGP(DSCHD, LOGL_ERROR, "Invalid TCH mode: %u\n", tch_mode);
+               return -EINVAL;
+       }
+
+       /* Shift buffer by 4 bursts for interleaving */
+       memcpy(buffer, buffer + 464, 464);
+
+       /* Check decoding result */
+       if (rc < 4) {
+               LOGP(DSCHD, LOGL_DEBUG, "Received bad TCH frame ending at "
+                       "fn=%u for %s\n", fn, lchan_desc->name);
+
+               l2_len = sched_bad_frame_ind(l2, rsl_cmode, tch_mode);
+       } else if (rc == GSM_MACBLOCK_LEN) {
+               /* FACCH received, forward it to the higher layers */
+               sched_send_data_ind(trx, ts, lchan, l2, GSM_MACBLOCK_LEN);
+               /* Send BFI instead of stolen TCH frame */
+               l2_len = sched_bad_frame_ind(l2, rsl_cmode, tch_mode);
+       } else {
+               /* A good TCH frame received */
+               l2_len = rc;
+       }
+
+       /* Send a traffic frame to the higher layers */
+       if (l2_len > 0)
+               sched_send_data_ind(trx, ts, lchan, l2, l2_len);
+
+       return 0;
+}
+
+int tx_tchf_fn(struct trx_instance *trx, struct trx_ts *ts,
+       struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid)
+{
+       const struct trx_lchan_desc *lchan_desc;
+       struct trx_ts_prim *prim;
+       ubit_t burst[GSM_BURST_LEN];
+       ubit_t *buffer, *offset;
+       uint8_t *mask, *l2;
+       const uint8_t *tsc;
+       size_t l2_len;
+       int rc;
+
+       /* Set up pointers */
+       lchan_desc = &trx_lchan_desc[lchan->type];
+       mask = &lchan->tx_burst_mask;
+       buffer = lchan->tx_bursts;
+
+       /* If we have encoded bursts */
+       if (*mask)
+               goto send_burst;
+
+       /* Wait until a first burst in period */
+       if (bid > 0)
+               return 0;
+
+       /* Check the current TCH mode */
+       switch (lchan->tch_mode) {
+       case GSM48_CMODE_SIGN:
+       case GSM48_CMODE_SPEECH_V1: /* FR */
+               l2_len = GSM_FR_BYTES;
+               break;
+       case GSM48_CMODE_SPEECH_EFR: /* EFR */
+               l2_len = GSM_EFR_BYTES;
+               break;
+       case GSM48_CMODE_SPEECH_AMR: /* AMR */
+               /**
+                * TODO: AMR requires a dedicated loop,
+                * which will be implemented later...
+                */
+               /* TODO: drop prim here */
+               LOGP(DSCHD, LOGL_ERROR, "AMR isn't supported yet\n");
+               return -ENOTSUP;
+       default:
+               /* TODO: drop prim here */
+               LOGP(DSCHD, LOGL_ERROR, "Invalid TCH mode: %u\n",
+                       lchan->tch_mode);
+               return -EINVAL;
+       }
+
+       /* Get a message from TX queue */
+       prim = sched_dequeue_tch_prim(&ts->tx_prims);
+       l2 = (uint8_t *) prim->payload;
+
+       /* Determine payload length */
+       if (prim->payload_len == GSM_MACBLOCK_LEN)
+               l2_len = GSM_MACBLOCK_LEN;
+
+       /* Shift buffer by 4 bursts back for interleaving */
+       memcpy(buffer, buffer + 464, 464);
+
+       /* Encode payload */
+       rc = gsm0503_tch_fr_encode(buffer, l2, l2_len, 1);
+       if (rc) {
+               LOGP(DSCHD, LOGL_ERROR, "Failed to encode L2 payload\n");
+
+               /* Remove primitive from queue and free memory */
+               llist_del(&prim->list);
+               talloc_free(prim);
+
+               return -EINVAL;
+       }
+
+send_burst:
+       /* Determine which burst should be sent */
+       offset = buffer + bid * 116;
+
+       /* Update mask */
+       *mask |= (1 << bid);
+
+       /* Choose proper TSC */
+       tsc = sched_nb_training_bits[trx->tsc];
+
+       /* Compose a new burst */
+       memset(burst, 0, 3); /* TB */
+       memcpy(burst + 3, offset, 58); /* Payload 1/2 */
+       memcpy(burst + 61, tsc, 26); /* TSC */
+       memcpy(burst + 87, offset + 58, 58); /* Payload 2/2 */
+       memset(burst + 145, 0, 3); /* TB */
+
+       LOGP(DSCHD, LOGL_DEBUG, "Transmitting %s fn=%u ts=%u burst=%u\n",
+               lchan_desc->name, fn, ts->index, bid);
+
+       /* Send burst to transceiver */
+       rc = trx_if_tx_burst(trx, ts->index, fn, trx->tx_power, burst);
+       if (rc) {
+               LOGP(DSCHD, LOGL_ERROR, "Could not send burst to 
transceiver\n");
+
+               /* Remove primitive from queue and free memory */
+               prim = llist_entry(ts->tx_prims.next, struct trx_ts_prim, list);
+               llist_del(&prim->list);
+               talloc_free(prim);
+
+               /* Reset mask */
+               *mask = 0x00;
+
+               return rc;
+       }
+
+       /* If we have sent the last (4/4) burst */
+       if (*mask == 0x0f) {
+               /* Get pointer to a prim which was sent */
+               prim = llist_entry(ts->tx_prims.next, struct trx_ts_prim, list);
+
+               /* Confirm data / traffic sending */
+               sched_send_data_conf(trx, ts, lchan, fn, prim->payload_len);
+
+               /* Remove primitive from queue and free memory */
+               llist_del(&prim->list);
+               talloc_free(prim);
+
+               /* Reset mask */
+               *mask = 0x00;
+       }
+
+       return 0;
+}
diff --git a/src/host/trxcon/sched_trx.h b/src/host/trxcon/sched_trx.h
index de7e073..268c6b7 100644
--- a/src/host/trxcon/sched_trx.h
+++ b/src/host/trxcon/sched_trx.h
@@ -22,6 +22,11 @@
 
 #define MAX_A5_KEY_LEN         (128 / 8)
 
+/* TS 101318 Chapter 5.1: 260 bits + 4bit sig */
+#define GSM_FR_BYTES           33
+/* TS 101318 Chapter 5.3: 244 bits + 4bit sig */
+#define GSM_EFR_BYTES          31
+
 /* Forward declaration to avoid mutual include */
 struct trx_lchan_state;
 struct trx_instance;
@@ -262,6 +267,7 @@
        size_t pl_len, uint8_t chan_nr, uint8_t link_id);
 int sched_trx_push_prim(struct trx_instance *trx,
        struct trx_ts_prim *prim, uint8_t chan_nr);
+struct trx_ts_prim *sched_dequeue_tch_prim(struct llist_head *queue);
 
 int sched_trx_handle_rx_burst(struct trx_instance *trx, uint8_t tn,
        uint32_t burst_fn, sbit_t *bits, uint16_t nbits, int8_t rssi, float 
toa);

-- 
To view, visit https://gerrit.osmocom.org/6803
To unsubscribe, visit https://gerrit.osmocom.org/settings

Gerrit-MessageType: newchange
Gerrit-Change-Id: If6b0eaede2b484484d2a824e7219ff04483266a1
Gerrit-PatchSet: 1
Gerrit-Project: osmocom-bb
Gerrit-Branch: master
Gerrit-Owner: Harald Welte <lafo...@gnumonks.org>

Reply via email to