meas_rep: utility function for processing of measurement reports
This provides two functions: get_meas_rep_avg() to obtain the sliding
window average of one particular field, and meas_rep_n_out_of_m_be()
to check if at least N out of M measurments are >= BE.
diff --git a/openbsc/src/meas_rep.c b/openbsc/src/meas_rep.c
new file mode 100644
index 0000000..4b9cc1a
--- /dev/null
+++ b/openbsc/src/meas_rep.c
@@ -0,0 +1,114 @@
+/* Measurement Report Processing */
+
+/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ *
+ * 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 <sys/types.h>
+
+#include <openbsc/gsm_data.h>
+#include <openbsc/meas_rep.h>
+
+static int get_field(const struct gsm_meas_rep *rep,
+ enum meas_rep_field field)
+{
+ switch (field) {
+ case MEAS_REP_DL_RXLEV_FULL:
+ return rep->dl.full.rx_lev;
+ case MEAS_REP_DL_RXLEV_SUB:
+ return rep->dl.sub.rx_lev;
+ case MEAS_REP_DL_RXQUAL_FULL:
+ return rep->dl.full.rx_qual;
+ case MEAS_REP_DL_RXQUAL_SUB:
+ return rep->dl.sub.rx_qual;
+ case MEAS_REP_UL_RXLEV_FULL:
+ return rep->ul.full.rx_lev;
+ case MEAS_REP_UL_RXLEV_SUB:
+ return rep->ul.sub.rx_lev;
+ case MEAS_REP_UL_RXQUAL_FULL:
+ return rep->ul.full.rx_qual;
+ case MEAS_REP_UL_RXQUAL_SUB:
+ return rep->ul.sub.rx_qual;
+ }
+
+ return 0;
+}
+
+
+unsigned int calc_initial_idx(unsigned int array_size,
+ unsigned int meas_rep_idx,
+ unsigned int num_values)
+{
+ int offs, idx;
+
+ /* from which element do we need to start if we're interested
+ * in an average of 'num' elements */
+ offs = meas_rep_idx - num_values;
+
+ if (offs < 0)
+ idx = array_size + offs;
+ else
+ idx = offs;
+
+ return idx;
+}
+
+/* obtain an average over the last 'num' fields in the meas reps */
+int get_meas_rep_avg(const struct gsm_lchan *lchan,
+ enum meas_rep_field field, unsigned int num)
+{
+ unsigned int i, idx;
+ int avg = 0;
+
+ idx = calc_initial_idx(ARRAY_SIZE(lchan->meas_rep),
+ lchan->meas_rep_idx, num);
+
+ for (i = 0; i < num; i++) {
+ int j = (idx+i) % ARRAY_SIZE(lchan->meas_rep);
+
+ avg += get_field(&lchan->meas_rep[j], field);
+ }
+
+ return avg / num;
+}
+
+/* Check if N out of M last values for FIELD are >= bd */
+int meas_rep_n_out_of_m_be(const struct gsm_lchan *lchan,
+ enum meas_rep_field field,
+ unsigned int n, unsigned int m, int be)
+{
+ unsigned int i, idx;
+ int count = 0;
+
+ idx = calc_initial_idx(ARRAY_SIZE(lchan->meas_rep),
+ lchan->meas_rep_idx, m);
+
+ for (i = 0; i < m; i++) {
+ int j = (idx + i) % ARRAY_SIZE(lchan->meas_rep);
+ int val = get_field(&lchan->meas_rep[j], field);
+
+ if (val >= be)
+ count++;
+
+ if (count >= n)
+ return 1;
+ }
+
+ return 0;
+}