codec_pref: handle S0-S15 in ASSIGNMENT REQUEST

Opposed to all other codecs that are common in GSM, AMR requires a codec
configuration that is expressed by a bitmask (S0 to S15) in the speech
codec list in the ASSIGNMENT REQUEST. Also the BSC acknowledges those
configuration in the ASSIGNMENT COMPLETE message.

At the moment osmo-bsc ignores all incoming configuration bits. The bits
in the ASSIGNMENT COMPLETE speech codec (choosen) field are hardcoded.

- Store the configuration bits while parsing the ASSIGNMENT COMPLETE
- Create an intersection with the configuration that is actually
  supported by the BSS
- Return the resulting (chosen) configuration bits with the assignment
  complete message.
- Use the (highest of the) agreed codec rates in RSL channel activation.

Change-Id: I2d8ded51b3eb4c003fe2da6f2d6f48d001b73737
Related: OS#3529

3 files changed, 5 insertions, 3 deletions

diff --git a/include/osmocom/bsc/codec_pref.h b/include/osmocom/bsc/codec_pref.h
index 09aaa604b..3085ad4f9 100644
--- a/include/osmocom/bsc/codec_pref.h
+++ b/include/osmocom/bsc/codec_pref.h
@@ -12,11 +12,11 @@ struct gsm_bts;
 
 int match_codec_pref(enum gsm48_chan_mode *chan_mode,
 		     bool *full_rate,
+		     uint16_t *s15_s0,
 		     const struct gsm0808_channel_type *ct,
 		     const struct gsm0808_speech_codec_list *scl,
-		     struct gsm_audio_support * const *audio_support,
-		     int audio_length,
-		     const struct bts_codec_conf *bts_codec);
+		     const struct bsc_msc_data *msc,
+		     const struct gsm_bts *bts);
 
 void gen_bss_supported_codec_list(struct gsm0808_speech_codec_list *scl,
 				  const struct bsc_msc_data *msc,
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 33a5a8dc6..7c91e5982 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -109,6 +109,7 @@ struct assignment_request {
 
 	enum gsm48_chan_mode chan_mode;
 	bool full_rate;
+	uint16_t s15_s0;
 };
 
 struct assignment_fsm_data {
diff --git a/include/osmocom/bsc/lchan_fsm.h b/include/osmocom/bsc/lchan_fsm.h
index 9fbf9b3dc..d2e872446 100644
--- a/include/osmocom/bsc/lchan_fsm.h
+++ b/include/osmocom/bsc/lchan_fsm.h
@@ -58,6 +58,7 @@ struct lchan_activate_info {
 	/* This always is for a specific lchan, so its lchan->type indicates full or half rate.
 	 * When a dyn TS was selected, the lchan->type has been set to the desired rate. */
 	enum gsm48_chan_mode chan_mode;
+	uint16_t s15_s0;
 	bool requires_voice_stream;
 	bool wait_before_switching_rtp;
 	uint16_t msc_assigned_cic;