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/*
* OsmocomBB <-> SDR connection bridge
* TDMA scheduler: primitive management
*
* (C) 2017 by Vadim Yanitskiy <axilirator@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 <osmocom/core/msgb.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/gsm/protocol/gsm_04_08.h>
#include "scheduler.h"
#include "sched_trx.h"
#include "trx_if.h"
#include "logging.h"
/**
* Initializes a new primitive by allocating memory
* and filling some meta-information (e.g. lchan type).
*
* @param trx TRX instance to be used as initial talloc context
* @param prim external prim pointer (will point to the allocated prim)
* @param pl_len prim payload length
* @param chan_nr RSL channel description (used to set a proper chan)
* @param link_id RSL link description (used to set a proper chan)
* @return zero in case of success, otherwise a error number
*/
int sched_prim_init(struct trx_instance *trx,
struct trx_ts_prim **prim, size_t pl_len,
uint8_t chan_nr, uint8_t link_id)
{
enum trx_lchan_type lchan_type;
struct trx_ts_prim *new_prim;
uint8_t len;
/* Determine lchan type */
lchan_type = sched_trx_chan_nr2lchan_type(chan_nr, link_id);
if (!lchan_type) {
LOGP(DSCH, LOGL_ERROR, "Couldn't determine lchan type "
"for chan_nr=%02x and link_id=%02x\n", chan_nr, link_id);
return -EINVAL;
}
/* How much memory do we need? */
len = sizeof(struct trx_ts_prim); /* Primitive header */
len += pl_len; /* Requested payload size */
/* Allocate a new primitive */
new_prim = talloc_zero_size(trx, len);
if (new_prim == NULL) {
LOGP(DSCH, LOGL_ERROR, "Failed to allocate memory\n");
return -ENOMEM;
}
/* Init primitive header */
new_prim->payload_len = pl_len;
new_prim->chan = lchan_type;
/* Set external pointer */
*prim = new_prim;
return 0;
}
/**
* Adds a primitive to the end of transmit queue of a particular
* timeslot, whose index is parsed from chan_nr.
*
* @param trx TRX instance
* @param prim to be enqueued primitive
* @param chan_nr RSL channel description
* @return zero in case of success, otherwise a error number
*/
int sched_prim_push(struct trx_instance *trx,
struct trx_ts_prim *prim, uint8_t chan_nr)
{
struct trx_ts *ts;
uint8_t tn;
/* Determine TS index */
tn = chan_nr & 0x7;
if (tn > 7) {
LOGP(DSCH, LOGL_ERROR, "Incorrect TS index %u\n", tn);
return -EINVAL;
}
/* Check whether required timeslot is allocated and configured */
ts = trx->ts_list[tn];
if (ts == NULL || ts->mf_layout == NULL) {
LOGP(DSCH, LOGL_ERROR, "Timeslot %u isn't configured\n", tn);
return -EINVAL;
}
/**
* Change talloc context of primitive
* from trx to the parent ts
*/
talloc_steal(ts, prim);
/* Add primitive to TS transmit queue */
llist_add_tail(&prim->list, &ts->tx_prims);
return 0;
}
#define CHAN_IS_TCH(chan) \
(chan == TRXC_TCHF || chan == TRXC_TCHH_0 || chan == TRXC_TCHH_1)
#define PRIM_IS_TCH(prim) \
CHAN_IS_TCH(prim->chan) && prim->payload_len != GSM_MACBLOCK_LEN
#define PRIM_IS_FACCH(prim) \
CHAN_IS_TCH(prim->chan) && prim->payload_len == GSM_MACBLOCK_LEN
/**
* Dequeues a TCH or FACCH frame, prioritizing the second.
* In case if a FACCH frame is found, a TCH frame is being
* dropped (i.e. replaced).
*
* @param queue a transmit queue to take a prim from
* @return a FACCH or TCH primitive, otherwise NULL
*/
static struct trx_ts_prim *sched_prim_dequeue_tch(struct llist_head *queue)
{
struct trx_ts_prim *facch = NULL;
struct trx_ts_prim *tch = NULL;
struct trx_ts_prim *i;
/* Attempt to find a pair of FACCH and TCH frames */
llist_for_each_entry(i, queue, list) {
/* Find one FACCH frame */
if (!facch && PRIM_IS_FACCH(i))
facch = i;
/* Find one TCH frame */
if (!tch && PRIM_IS_TCH(i))
tch = i;
/* If both are found */
if (facch && tch)
break;
}
/* Prioritize FACCH */
if (facch && tch) {
/* We found a pair, dequeue both */
llist_del(&facch->list);
llist_del(&tch->list);
/* Drop TCH */
talloc_free(tch);
/* FACCH replaces TCH */
return facch;
} else if (facch) {
/* Only FACCH was found */
llist_del(&facch->list);
return facch;
} else if (tch) {
/* Only TCH was found */
llist_del(&tch->list);
return tch;
}
/**
* Nothing was found,
* e.g. only SACCH frames are in queue
*/
return NULL;
}
/**
* Dequeues a single primitive of required type
* from a specified transmit queue.
*
* @param queue a transmit queue to take a prim from
* @param lchan_type required primitive type
* @return a primitive or NULL if not found
*/
struct trx_ts_prim *sched_prim_dequeue(struct llist_head *queue,
enum trx_lchan_type lchan_type)
{
struct trx_ts_prim *prim;
/* There is nothing to dequeue */
if (llist_empty(queue))
return NULL;
/* TCH requires FACCH prioritization, so handle it separately */
if (CHAN_IS_TCH(lchan_type))
return sched_prim_dequeue_tch(queue);
llist_for_each_entry(prim, queue, list) {
if (prim->chan == lchan_type) {
llist_del(&prim->list);
return prim;
}
}
return NULL;
}
/**
* Drops the current primitive of specified logical channel
*
* @param lchan a logical channel to drop prim from
*/
void sched_prim_drop(struct trx_lchan_state *lchan)
{
/* Forget this primitive */
talloc_free(lchan->prim);
lchan->prim = NULL;
}
/**
* Flushes a queue of primitives
*
* @param list list of prims going to be flushed
*/
void sched_prim_flush_queue(struct llist_head *list)
{
struct trx_ts_prim *prim, *prim_next;
llist_for_each_entry_safe(prim, prim_next, list, list) {
llist_del(&prim->list);
talloc_free(prim);
}
}
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