osmocom
/
libosmocore
mirror of https://gerrit.osmocom.org/libosmocore
11
0
Fork 0
Code Issues Releases Wiki Activity

gsm_08_08: define GSM0808_SCT_EXT (separately) 

As per 3GPP TS 48.008, section 3.2.2.103, the "Codec Type" field may
contain either a certain 3GPP Speech Codec Type directly (4 bit value),
or the so called "Codec Extension" = 0xFh, in which case the real Codec
Type follows in the next octet as "Extended Codec Type".

CSD is such an example, the encoding is defined as follows:

     8    7    6    5    4    3    2    1
  +----+----+----+----+-------------------+
  | -- | PI | PT | -- |        0xFh       |
  +----+----+----+----+-------------------+
  |      Extended Codec Type (CSData)     |
  +----+----+-----------------------------+
  | R2 | R3 |                             |
  +----+----+-----------------------------+

  CSData is coded with 0xFDh or '1111 1101' (0xfd).

Let's have the "Codec Extension" value clearly defined in the header
file, but intentionally separate from the other GSM0808_SCT_* values.

Change-Id: Iafaa25070684d2ba400c75fa33e803651a5ce857
Related: OS#6110, OS#4393, OS#4394
This commit is contained in:
Vadim Yanitskiy 2023-07-25 03:23:08 +07:00
parent 547a65aae2
commit f93ef0c634
3 changed files with 10 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/osmocom/gsm/protocol/gsm_08_08.h
View File

@ -557,6 +557,12 @@ enum gsm0808_speech_codec_type {
GSM0808_SCT_CSD = 0xfd, /*!< CSData (see also TS 26.103) */
};
/* Codec Extension (the real Codec Type follows in the next octet).
* This value is intentionally not included in gsm0808_speech_codec_type,
* because {enc,dec}_speech_codec() functions take care of the extended
* encoding internally. It shall not be used in struct gsm0808_speech_codec. */
#define GSM0808_SCT_EXT 0x0f
extern const struct value_string gsm0808_speech_codec_type_names[];
static inline const char *gsm0808_speech_codec_type_name(enum gsm0808_speech_codec_type val)
{ return get_value_string(gsm0808_speech_codec_type_names, val); }

1
src/gsm/gsm0808.c
View File

@ -2478,6 +2478,7 @@ const struct value_string gsm0808_speech_codec_type_names[] = {
{ GSM0808_SCT_HR3, "HR3" },
{ GSM0808_SCT_HR4, "HR4" },
{ GSM0808_SCT_HR6, "HR6" },
{ GSM0808_SCT_EXT, "Codec Extension" },
{ GSM0808_SCT_CSD, "CSD" },
{ 0, NULL }
};

6
src/gsm/gsm0808_utils.c
View File

@ -255,7 +255,7 @@ static int enc_speech_codec(struct msgb *msg,
header |= (1 << 4);
if (type_extended) {
header |= 0x0f;
header |= GSM0808_SCT_EXT;
msgb_put_u8(msg, header);
msgb_put_u8(msg, sc->type);
} else {
@ -347,7 +347,7 @@ int gsm0808_dec_speech_codec(struct gsm0808_speech_codec *sc,
/* An extended codec type needs at least two fields,
* bail if the input data length is not sufficient. */
if ((header & 0x0F) == 0x0F && len < 2)
if ((header & 0x0F) == GSM0808_SCT_EXT && len < 2)
return -EINVAL;
elem++;
@ -362,7 +362,7 @@ int gsm0808_dec_speech_codec(struct gsm0808_speech_codec *sc,
if (header & (1 << 4))
sc->tf = true;
if ((header & 0x0F) != 0x0F) {
if ((header & 0x0F) != GSM0808_SCT_EXT) {
sc->type = (header & 0x0F);
} else {
sc->type = *elem;