add some utility functions for paging related calculation (TS 05.02)
diff --git a/include/osmocom/gsm/gsm0502.h b/include/osmocom/gsm/gsm0502.h
new file mode 100644
index 0000000..de92c63
--- /dev/null
+++ b/include/osmocom/gsm/gsm0502.h
@@ -0,0 +1,35 @@
+#ifndef OSMOCOM_GSM_0502_H
+#define OSMOCOM_GSM_0502_H
+
+#include <stdint.h>
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/protocol/gsm_08_58.h>
+
+/* Table 5 Clause 7 TS 05.02 */
+static inline unsigned int
+gsm0502_get_n_pag_blocks(struct gsm48_control_channel_descr *chan_desc)
+{
+ if (chan_desc->ccch_conf == RSL_BCCH_CCCH_CONF_1_C)
+ return 3 - chan_desc->bs_ag_blks_res;
+ else
+ return 9 - chan_desc->bs_ag_blks_res;
+}
+
+/* Chapter 6.5.2 of TS 05.02 */
+static inline unsigned int
+gsm0502_get_ccch_group(uint64_t imsi, unsigned int bs_cc_chans,
+ unsigned int n_pag_blocks)
+{
+ return (imsi % 1000) % (bs_cc_chans * n_pag_blocks) / n_pag_blocks;
+}
+
+/* Chapter 6.5.2 of TS 05.02 */
+static inline unsigned int
+gsm0502_get_paging_group(uint64_t imsi, unsigned int bs_cc_chans,
+ int n_pag_blocks)
+{
+ return (imsi % 1000) % (bs_cc_chans * n_pag_blocks) % n_pag_blocks;
+}
+
+#endif