rest_octets: Implement actual SI6 rest octets encoding

There's very little sense behind introducing a function into
libosmogsm which doesn't implement 90% of the spec.  Let's allow
the caller to provide the various optional bits of information to
the encoder, rather than generating mostly static SI6 rest octets.

Change-Id: Id75005a0c4a02ce7f809692d58b3bd226bc582b2

2 files changed, 73 insertions, 12 deletions

diff --git a/include/osmocom/gsm/gsm48_rest_octets.h b/include/osmocom/gsm/gsm48_rest_octets.h
index bc5023a6..7163672c 100644
--- a/include/osmocom/gsm/gsm48_rest_octets.h
+++ b/include/osmocom/gsm/gsm48_rest_octets.h
@@ -20,7 +20,44 @@ int osmo_gsm48_rest_octets_si2quater_encode(uint8_t *data, uint8_t si2q_index, u
 					    size_t *e_offset);
 int osmo_gsm48_rest_octets_si2ter_encode(uint8_t *data);
 int osmo_gsm48_rest_octets_si2bis_encode(uint8_t *data);
-int osmo_gsm48_rest_octets_si6_encode(uint8_t *data, bool is1800_net);
+
+struct osmo_gsm48_si_pch_nch_info {
+	bool present;
+	bool paging_channel_restructuring;
+	uint8_t nln_sacch;
+	bool call_priority_present;
+	uint8_t call_priority;
+	bool nln_status_sacch;
+};
+
+struct osmo_gsm48_si_vbs_vgcs_options {
+	bool present;
+	bool inband_notifications;
+	bool inband_pagings;
+};
+
+struct osmo_gsm48_si_dtm_support {
+	bool present;
+	uint8_t rac;
+	uint8_t max_lapdm;
+};
+
+struct osmo_gsm48_si_gprs_ms_txpwr_max_ccch {
+	bool present;
+	uint8_t max_txpwr;
+};
+
+struct osmo_gsm48_si6_ro_info {
+	struct osmo_gsm48_si_pch_nch_info pch_nch_info;
+	struct osmo_gsm48_si_vbs_vgcs_options vbs_vgcs_options;
+	struct osmo_gsm48_si_dtm_support dtm_support;
+	bool band_indicator_1900;
+	struct osmo_gsm48_si_gprs_ms_txpwr_max_ccch gprs_ms_txpwr_max_ccch;
+	/* MBMS: not supported in Osmocom */
+	/* AMR config (group channel): not supported in Osmocom */
+};
+
+int osmo_gsm48_rest_octets_si6_encode(uint8_t *data, const struct osmo_gsm48_si6_ro_info *in);
 
 struct osmo_gsm48_si_selection_params {
 	uint16_t penalty_time:5,
diff --git a/src/gsm/gsm48_rest_octets.c b/src/gsm/gsm48_rest_octets.c
index d5c93fe8..c1e4b308 100644
--- a/src/gsm/gsm48_rest_octets.c
+++ b/src/gsm/gsm48_rest_octets.c
@@ -687,7 +687,7 @@ int osmo_gsm48_rest_octets_si4_encode(uint8_t *data, const struct osmo_gsm48_si_
 { L | H < GPRS_MS_TXPWR_MAX_CCH : bit (5) > }
 <implicit spare >;
 */
-int osmo_gsm48_rest_octets_si6_encode(uint8_t *data, bool is1800_net)
+int osmo_gsm48_rest_octets_si6_encode(uint8_t *data, const struct osmo_gsm48_si6_ro_info *in)
 {
 	struct bitvec bv;
 
@@ -695,19 +695,43 @@ int osmo_gsm48_rest_octets_si6_encode(uint8_t *data, bool is1800_net)
 	bv.data = data;
 	bv.data_len = 1;
 
-	/* no PCH/NCH info */
-	bitvec_set_bit(&bv, L);
-	/* no VBS/VGCS options */
-	bitvec_set_bit(&bv, L);
-	/* no DTM_support */
-	bitvec_set_bit(&bv, L);
-	/* band indicator */
-	if (is1800_net)
+	if (in->pch_nch_info.present) {
+		bitvec_set_bit(&bv, H);
+		bitvec_set_bit(&bv, !!in->pch_nch_info.paging_channel_restructuring);
+		bitvec_set_uint(&bv, in->pch_nch_info.nln_sacch, 2);
+		if (in->pch_nch_info.call_priority_present) {
+			bitvec_set_bit(&bv, 1);
+			bitvec_set_uint(&bv, in->pch_nch_info.call_priority, 3);
+		} else
+			bitvec_set_bit(&bv, 0);
+		bitvec_set_bit(&bv, !!in->pch_nch_info.nln_status_sacch);
+	} else
+		bitvec_set_bit(&bv, L);
+
+	if (in->vbs_vgcs_options.present) {
+		bitvec_set_bit(&bv, H);
+		bitvec_set_bit(&bv, !!in->vbs_vgcs_options.inband_notifications);
+		bitvec_set_bit(&bv, !!in->vbs_vgcs_options.inband_pagings);
+	} else
+		bitvec_set_bit(&bv, L);
+
+	if (in->dtm_support.present) {
+		bitvec_set_bit(&bv, H);
+		bitvec_set_uint(&bv, in->dtm_support.rac, 8);
+		bitvec_set_uint(&bv, in->dtm_support.max_lapdm, 3);
+	} else
 		bitvec_set_bit(&bv, L);
+
+	if (in->band_indicator_1900)
+		bitvec_set_bit(&bv, H);
 	else
+		bitvec_set_bit(&bv, L);
+
+	if (in->gprs_ms_txpwr_max_ccch.present) {
 		bitvec_set_bit(&bv, H);
-	/* no GPRS_MS_TXPWR_MAX_CCH */
-	bitvec_set_bit(&bv, L);
+		bitvec_set_uint(&bv, in->gprs_ms_txpwr_max_ccch.max_txpwr, 5);
+	} else
+		bitvec_set_bit(&bv, L);
 
 	bitvec_spare_padding(&bv, (bv.data_len * 8) - 1);
 	return bv.data_len;