gsm0808: add encoder for cause codes and use it

At the moment the all gsm0808 cause codes are encoded directly using the
tlv API directly to put a one byte TLV field. This works ok for most
situations where the cause code consists of a single byte. However,
gsm0808 specifies a two byte cause code model where cause codes may be
extended up to two bytes. Instead of implementing the encoding over and
over and again, let's rather have an encoder function we can call.

- Add an encoder function that can generate single byte and extended
  cause codeds and makes the length decision automatically.

- Use only this function to append cause codes

Change-Id: I71d58fad89502a43532f60717ca022c15c73f8bb

1 files changed, 1 insertions, 0 deletions

diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index e9a9e4f2..dc4e0a69 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -183,6 +183,7 @@ gsm0808_create_handover_complete;
 gsm0808_create_handover_failure;
 gsm0808_create_handover_performed;
 gsm0808_prepend_dtap_header;
+gsm0808_enc_cause;
 gsm0808_enc_aoip_trasp_addr;
 gsm0808_dec_aoip_trasp_addr;
 gsm0808_enc_speech_codec;