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-rw-r--r--openbsc/src/libbsc/Makefile.am3
-rw-r--r--openbsc/src/libbsc/pdch_defrag.c159
2 files changed, 161 insertions, 1 deletions
diff --git a/openbsc/src/libbsc/Makefile.am b/openbsc/src/libbsc/Makefile.am
index 48880d9..ea0bddc 100644
--- a/openbsc/src/libbsc/Makefile.am
+++ b/openbsc/src/libbsc/Makefile.am
@@ -24,5 +24,6 @@ libbsc_a_SOURCES = abis_nm.c abis_nm_vty.c \
arfcn_range_encode.c bsc_ctrl_commands.c \
bsc_ctrl_lookup.c \
net_init.c \
- bsc_dyn_pdch.c
+ bsc_dyn_pdch.c \
+ pdch_defrag.c
diff --git a/openbsc/src/libbsc/pdch_defrag.c b/openbsc/src/libbsc/pdch_defrag.c
new file mode 100644
index 0000000..f8b3145
--- /dev/null
+++ b/openbsc/src/libbsc/pdch_defrag.c
@@ -0,0 +1,159 @@
+/* (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 <stdbool.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_lchan(struct gsm_bts *bts,
+ enum gsm_phys_chan_config type,
+ bool forward)
+{
+ struct gsm_bts_trx *trx;
+ struct gsm_lchan *lc;
+ int i, start, stop, dir;
+
+ if (forward) {
+ /* check TS 0..7 */
+ start = 0;
+ stop = 8;
+ dir = 1;
+ } else {
+ /* check TS 7..0 */
+ start = 7;
+ stop = -1;
+ dir = -1;
+ }
+
+ llist_for_each_entry(trx, &bts->trx_list, list) {
+ for (i = start; i != stop; i += dir) {
+ if (trx->ts[i].pchan == type) {
+ lc = &trx->ts[i].lchan[0];
+ if (lc->state == LCHAN_S_ACTIVE)
+ return lc;
+ }
+ }
+ }
+
+ return NULL;
+}
+
+#define LOGTSP(ss, ll, ts, fmt, args...) \
+ LOGP(ss, ll, "(BTS %u, TRX %u, TS %u) " fmt, \
+ ts->trx->bts->nr, ts->trx->nr, ts->nr, \
+ ##args)
+
+/* Defragment TCH/F+PDCH channels to remove gaps between active
+ * GSM_PCHAN_TCH_F_PDCH slots. Assign active connections to standard TCH/F or
+ * to consecutive TCH/F+PDCH channels.
+ *
+ * This function depends on being re-triggered whenever a channel has been
+ * released: each reassignment for defragmentation includes a channel release,
+ * which should trigger another invocation, and defragmentation will continue.
+ *
+ * Look up the last active TCH/F+PDCH (highest TRX/TS number). If there
+ * is a TCH/F or a free TCH/F+PDCH on a lower TRX/TS number, re-assign it.
+ * If allocation order is reversed, re-assign in reverse direction instead.
+ */
+void do_pdch_defrag(struct gsm_bts *bts)
+{
+ struct gsm_lchan *old_lchan = NULL, *new_lchan;
+ int rc;
+ int want_dir;
+ int is_dir;
+
+ /* Find the "last" lchan in use, according to chan_alloc_reverse: if
+ * reversed, find the highest-numbered lchan == start looking from the
+ * back. */
+ old_lchan = find_lchan(bts, GSM_PCHAN_TCH_F_PDCH,
+ bts->chan_alloc_reverse? true : false);
+
+ /* if there is no candidate on GSM_PCHAN_TCH_F_PDCH, we are done */
+ /* FIXME: for multi-TRX, if the first TRX's last lchan doesn't need
+ * re-assignment, the other TRXes are not going to be checked. */
+ if (!old_lchan)
+ return;
+
+ LOGTSP(DHODEC, LOGL_DEBUG, old_lchan->ts,
+ "A shared TCH/F+PDCH is in use, check for reassignment.\n");
+
+ /* allocate new lchan */
+ new_lchan = lchan_alloc(bts, GSM_LCHAN_TCH_F, 0);
+ /* no free destination for candidate */
+ if (!new_lchan) {
+ LOGTSP(DHODEC, LOGL_DEBUG, old_lchan->ts,
+ "-> 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) {
+ LOGTSP(DHODEC, LOGL_DEBUG, new_lchan->ts,
+ "<- New channel for candidate is also a TCH/F+PDCH.\n");
+ /* be sure to move to lower number (or to higher number in case
+ * of reverse allocation) */
+ want_dir = bts->chan_alloc_reverse ? 1 : -1;
+ is_dir = new_lchan->ts->trx->nr - old_lchan->ts->trx->nr;
+
+ if (is_dir == 0) {
+ /* TRX number stays the same, check TS numbers. */
+ is_dir = new_lchan->ts->nr - old_lchan->ts->nr;
+ }
+
+ /* If is_dir were 0 here, new_lchan == old_lchan, which should
+ * never happen. Even if it does, that would mean no decrease
+ * in fragmentation... */
+
+ if ((is_dir > 0) != (want_dir > 0)) {
+ LOGP(DHODEC, LOGL_DEBUG,
+ "-> Move does not lower fragmentation:"
+ " TRX %u TS %u to TRX %u TS %u%s\n",
+ old_lchan->ts->trx->nr, old_lchan->ts->nr,
+ new_lchan->ts->trx->nr, new_lchan->ts->nr,
+ bts->chan_alloc_reverse ? " (reverse allocation)" : "");
+ lchan_free(new_lchan);
+ return;
+ }
+ } else {
+ LOGTSP(DHODEC, LOGL_DEBUG, new_lchan->ts,
+ "<- New channel for candidate is a TCH/F.\n");
+ }
+
+ rc = bsc_handover_start(old_lchan, new_lchan, new_lchan->ts->trx->bts);
+ 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 take further action here regardless of
+ * re-assignment success or failure, because in both cases a channel is
+ * freed, and this defragmentation should be triggered again.
+ */
+ /* FIXME: does re-assignment failure mean infinite looping/recursion!? */
+}
+