diff options
| author | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2023-07-25 03:23:08 +0700 |
|---|---|---|
| committer | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2023-07-25 04:23:12 +0700 |
| commit | f93ef0c634a78b4d783a3807683f9d714f48f543 (patch) | |
| tree | f77820c3c5f8fb429b9c3db80317f1d37f1220fb | |
| parent | 547a65aae20f5e152084e7a05f9d2ec1c692ec1c (diff) | |
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
| -rw-r--r-- | include/osmocom/gsm/protocol/gsm_08_08.h | 6 | ||||
| -rw-r--r-- | src/gsm/gsm0808.c | 1 | ||||
| -rw-r--r-- | src/gsm/gsm0808_utils.c | 6 |
3 files changed, 10 insertions, 3 deletions
diff --git a/include/osmocom/gsm/protocol/gsm_08_08.h b/include/osmocom/gsm/protocol/gsm_08_08.h index 967e4fe5..1e211dc9 100644 --- a/include/osmocom/gsm/protocol/gsm_08_08.h +++ b/include/osmocom/gsm/protocol/gsm_08_08.h @@ -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); } diff --git a/src/gsm/gsm0808.c b/src/gsm/gsm0808.c index d115888e..6ba6ef2a 100644 --- a/src/gsm/gsm0808.c +++ b/src/gsm/gsm0808.c @@ -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 } }; diff --git a/src/gsm/gsm0808_utils.c b/src/gsm/gsm0808_utils.c index b8e1ff0f..778630d6 100644 --- a/src/gsm/gsm0808_utils.c +++ b/src/gsm/gsm0808_utils.c @@ -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; |