From 507c0a363a7e55040b3925858299966f849b6c78 Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Thu, 30 May 2013 10:29:36 +0200
Subject: HO: Count number of free timeslot on a given BTS

This is needed for handover algorithm to balance free slots and to prevent
congestion of one cell, while other cells still have free capacities.
---
 openbsc/include/openbsc/chan_alloc.h |  3 +++
 openbsc/src/libbsc/chan_alloc.c      | 47 ++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/openbsc/include/openbsc/chan_alloc.h b/openbsc/include/openbsc/chan_alloc.h
index f2d3c781d..63c072496 100644
--- a/openbsc/include/openbsc/chan_alloc.h
+++ b/openbsc/include/openbsc/chan_alloc.h
@@ -35,6 +35,9 @@ struct gsm_bts_trx_ts *ts_alloc(struct gsm_bts *bts,
 /* Regular physical channel (TS) */
 void ts_free(struct gsm_bts_trx_ts *ts);
 
+/* Count number of free TS of given pchan type */
+int lc_count_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan);
+
 /* Find an allocated channel for a specified subscriber */
 struct gsm_subscriber_connection *connection_for_subscr(struct gsm_subscriber *subscr);
 
diff --git a/openbsc/src/libbsc/chan_alloc.c b/openbsc/src/libbsc/chan_alloc.c
index 3feecc59c..5a7b3f42e 100644
--- a/openbsc/src/libbsc/chan_alloc.c
+++ b/openbsc/src/libbsc/chan_alloc.c
@@ -224,6 +224,53 @@ _lc_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan)
 	return &ts->lchan[0];
 }
 
+static int
+_lc_count_trx(struct gsm_bts_trx *trx, enum gsm_phys_chan_config pchan)
+{
+	struct gsm_bts_trx_ts *ts;
+	int j, ss;
+	int count = 0;
+
+	if (!trx_is_usable(trx))
+		return 0;
+
+	for (j = 0; j < 8; j++) {
+		ts = &trx->ts[j];
+		if (!ts_is_usable(ts))
+			continue;
+		/* ip.access dynamic TCH/F + PDCH combination */
+		if (ts->pchan == GSM_PCHAN_TCH_F_PDCH &&
+		    pchan == GSM_PCHAN_TCH_F) {
+			/* we can only consider such a dynamic channel
+			 * if the PDCH is currently inactive */
+			if (ts->flags & TS_F_PDCH_MODE)
+				continue;
+		} else if (ts->pchan != pchan)
+			continue;
+		/* check if all sub-slots are allocated yet */
+		for (ss = 0; ss < subslots_per_pchan[pchan]; ss++) {
+			struct gsm_lchan *lc = &ts->lchan[ss];
+			if (lc->type == GSM_LCHAN_NONE &&
+			    lc->state == LCHAN_S_NONE)
+				count++;
+		}
+	}
+
+	return count;
+}
+
+/* Count number of free TS of given pchan type */
+int lc_count_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan)
+{
+	struct gsm_bts_trx *trx;
+	int count = 0;
+
+	llist_for_each_entry(trx, &bts->trx_list, list)
+		count += _lc_count_trx(trx, pchan);
+
+	return count;
+}
+
 /* Allocate a logical channel */
 struct gsm_lchan *lchan_alloc(struct gsm_bts *bts, enum gsm_chan_t type,
 			      int allow_bigger)
-- 
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