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/* (C) 2013 by Andreas Eversberg <andreas@eversberg.eu>
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdlib.h>
#include <errno.h>
#include <openbsc/debug.h>
#include <openbsc/gsm_data.h>
#include <openbsc/handover.h>
#include <openbsc/pdch_defrag.h>
#include <openbsc/chan_alloc.h>
static struct gsm_lchan *find_shared_forward(struct gsm_bts *bts)
{
struct gsm_bts_trx *trx;
struct gsm_lchan *lc;
int j;
llist_for_each_entry(trx, &bts->trx_list, list) {
for (j = 0; j < 8; j++) {
/* find first TCH/F+PDCH */
if (trx->ts[j].pchan == GSM_PCHAN_TCH_F_PDCH) {
lc = &trx->ts[j].lchan[0];
if (lc->state == LCHAN_S_ACTIVE)
return lc;
}
}
}
return NULL;
}
static struct gsm_lchan *find_shared_reverse(struct gsm_bts *bts)
{
struct gsm_bts_trx *trx;
struct gsm_lchan *lc;
int j;
llist_for_each_entry_reverse(trx, &bts->trx_list, list) {
for (j = 7; j >= 0; j--) {
/* find last TCH/F+PDCH */
if (trx->ts[j].pchan == GSM_PCHAN_TCH_F_PDCH) {
lc = &trx->ts[j].lchan[0];
if (lc->state == LCHAN_S_ACTIVE)
return lc;
}
}
}
return NULL;
}
static void debug_bts_trx_ts(struct gsm_bts_trx_ts *ts)
{
LOGPC(DHODEC, LOGL_DEBUG, " (BTS %u, TRX %u, TS %u)\n",
ts->trx->bts->nr, ts->trx->nr, ts->nr);
}
/* Try to move a TCH/F+PDCH candidate to maintain as much free and consecutive
* GSM_PCHAN_TCH_F_PDCH slots as possible.
*
* This algorithm is triggered whenever a channel has been released.
*
* The last (highest TRX/TS number) and active TCH/F+PDCH is searched. If there
* is a TCH/F or a free TCH/F+PDCH on a lower TRX/TS number, assignment is
* triggered. (When allocation order is reversed, this algorithm handles TRX/TS
* numbers in reversed order also.
*
* This algorithm ensures that gaps between active TCH/F+PDCH channels are
* removed, by assigning active connections to standard TCH/F or by assigning
* them to consecutive TCH/F+PDCH channels.
*/
void do_pdch_defrag(struct gsm_bts *bts)
{
struct gsm_lchan *old_lchan = NULL, *new_lchan;
int rc;
/* search TCH/F+PDCH in reverse order of allocation */
if (bts->chan_alloc_reverse) {
/* search from first to last TRX/TS */
old_lchan = find_shared_forward(bts);
} else {
/* search from last to first TRX/TS */
old_lchan = find_shared_reverse(bts);
}
/* if there is no candidate on GSM_PCHAN_TCH_F_PDCH, we are done */
if (!old_lchan)
return;
LOGP(DHODEC, LOGL_DEBUG, "A shared TCH/F+PDCH is in use, check if we "
"can move connection.");
debug_bts_trx_ts(old_lchan->ts);
/* allocate new lchan */
new_lchan = lchan_alloc(bts, GSM_LCHAN_TCH_F, 0);
/* no free destination for candidate */
if (!new_lchan) {
LOGP(DHODEC, LOGL_DEBUG, "-> Cannot move, no other TCH/F "
"available.\n");
return;
}
/* if new TS is also a GSM_PCHAN_TCH_F_PDCH */
if (new_lchan->ts->pchan == GSM_PCHAN_TCH_F_PDCH) {
LOGP(DHODEC, LOGL_DEBUG, "-> New channel for candidate is also "
"a TCH/F+PDCH.");
debug_bts_trx_ts(new_lchan->ts);
/* be sure to move down (or up at reverse allocation) */
if (bts->chan_alloc_reverse) {
/* new TS is lower */
if (new_lchan->ts->trx->nr < old_lchan->ts->trx->nr) {
LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
"lower fragmentation, new TRX has "
"lower number.\n");
goto free_lchan;
}
if (new_lchan->ts->trx->nr == old_lchan->ts->trx->nr
&& new_lchan->ts->nr < old_lchan->ts->nr) {
LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
"lower fragmentation, new TS has "
"lower number.\n");
goto free_lchan;
}
} else {
/* new TS is higher */
if (new_lchan->ts->trx->nr > old_lchan->ts->trx->nr) {
goto free_lchan;
LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
"lower fragmentation, new TRX has "
"higher number.\n");
}
if (new_lchan->ts->trx->nr == old_lchan->ts->trx->nr
&& new_lchan->ts->nr > old_lchan->ts->nr) {
LOGP(DHODEC, LOGL_DEBUG, "-> Move does not "
"lower fragmentation, new TS has "
"higher number.\n");
goto free_lchan;
}
}
} else {
LOGP(DHODEC, LOGL_DEBUG, "-> New channel for candidate is a "
"TCH/F.");
debug_bts_trx_ts(new_lchan->ts);
}
rc = bsc_handover_start(old_lchan, new_lchan, new_lchan->ts->trx->bts,
1);
if (rc) {
LOGP(DHODEC, LOGL_NOTICE, "Cannot trigger assignment to "
"defragment TCH/F+PDCH slots.\n");
} else {
LOGP(DHODEC, LOGL_NOTICE, "Triggered assignment to defragment "
"TCH/F+PDCH slots.\n");
}
/* We do not need to check, if assignment is ongoing or if it fails,
* because in both cases a channel is freed, so this defragmentation
* is triggered again.
*/
return;
free_lchan:
lchan_free(new_lchan);
}
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