gsm0808: Add utils for Speech Codec List and Speech Codec
The planned support for true A over IP requires the encoding and
decoding of a so called "Speech Codec Element" element.
This commt adds parsing functionality and tests for the element
mentioned above, however, it is not yet actively used.
Change-Id: I0e1e2edf47adaa45b22d4b0bcae3640dba7ca200
diff --git a/src/gsm/gsm0808_utils.c b/src/gsm/gsm0808_utils.c
index df24e2b..eef6146 100644
--- a/src/gsm/gsm0808_utils.c
+++ b/src/gsm/gsm0808_utils.c
@@ -31,6 +31,7 @@
#define IP_V6_ADDR_LEN 16
#define IP_PORT_LEN 2
+
/* Encode AoIP transport address element */
uint8_t gsm0808_enc_aoip_trasp_addr(struct msgb *msg,
const struct sockaddr_storage *ss)
@@ -120,3 +121,188 @@
return (int)(elem - old_elem);
}
+
+/* Helper function for gsm0808_enc_speech_codec()
+ * and gsm0808_enc_speech_codec_list() */
+static uint8_t enc_speech_codec(struct msgb *msg,
+ const struct gsm0808_speech_codec *sc)
+{
+ /* See also 3GPP TS 48.008 3.2.2.103 Speech Codec List */
+ uint8_t header = 0;
+ uint8_t *old_tail;
+
+ old_tail = msg->tail;
+
+ if (sc->fi)
+ header |= (1 << 7);
+ if (sc->pi)
+ header |= (1 << 6);
+ if (sc->pt)
+ header |= (1 << 5);
+ if (sc->tf)
+ header |= (1 << 4);
+ if (sc->type_extended) {
+ header |= 0x0f;
+ msgb_put_u8(msg, header);
+ } else {
+ OSMO_ASSERT(sc->type < 0x0f);
+ header |= sc->type;
+ msgb_put_u8(msg, header);
+ return (uint8_t) (msg->tail - old_tail);
+ }
+
+ msgb_put_u8(msg, sc->type);
+
+ if (sc->cfg_present)
+ msgb_put_u16(msg, sc->cfg);
+
+ return (uint8_t) (msg->tail - old_tail);
+}
+
+/* Encode Speech Codec element */
+uint8_t gsm0808_enc_speech_codec(struct msgb *msg,
+ const struct gsm0808_speech_codec *sc)
+{
+ uint8_t *old_tail;
+ uint8_t *tlv_len;
+
+ OSMO_ASSERT(msg);
+ OSMO_ASSERT(sc);
+
+ msgb_put_u8(msg, GSM0808_IE_SPEECH_CODEC);
+ tlv_len = msgb_put(msg, 1);
+ old_tail = msg->tail;
+
+ enc_speech_codec(msg, sc);
+
+ *tlv_len = (uint8_t) (msg->tail - old_tail);
+ return *tlv_len + 2;
+}
+
+/* Decode Speech Codec element */
+int gsm0808_dec_speech_codec(struct gsm0808_speech_codec *sc,
+ const uint8_t *elem, uint8_t len)
+{
+ /* See also 3GPP TS 48.008 3.2.2.103 Speech Codec List */
+ uint8_t header;
+ const uint8_t *old_elem = elem;
+
+ OSMO_ASSERT(sc);
+ if (!elem)
+ return -EINVAL;
+ if (len <= 0)
+ return -EINVAL;
+
+ memset(sc, 0, sizeof(*sc));
+
+ header = *elem;
+
+ /* Malformed elements */
+ if ((header & 0x0F) == 0x0F && len < 2)
+ return -EINVAL;
+ else if ((header & 0x0F) != 0x0F && len < 1)
+ return -EINVAL;
+
+ elem++;
+ len--;
+
+ if (header & (1 << 7))
+ sc->fi = true;
+ if (header & (1 << 6))
+ sc->pi = true;
+ if (header & (1 << 5))
+ sc->pt = true;
+ if (header & (1 << 4))
+ sc->tf = true;
+
+ if ((header & 0x0F) != 0x0F) {
+ sc->type = (header & 0x0F);
+ return (int)(elem - old_elem);
+ }
+
+ sc->type = *elem;
+ elem++;
+ len--;
+
+ sc->type_extended = true;
+
+ if (len < 2)
+ return (int)(elem - old_elem);
+
+ sc->cfg = osmo_load16be(elem);
+ elem += 2;
+ sc->cfg_present = true;
+
+ return (int)(elem - old_elem);
+}
+
+/* Encode Speech Codec list */
+uint8_t gsm0808_enc_speech_codec_list(struct msgb *msg,
+ const struct gsm0808_speech_codec_list *scl)
+{
+ uint8_t *old_tail;
+ uint8_t *tlv_len;
+ unsigned int i;
+ uint8_t rc;
+ unsigned int bytes_used = 0;
+
+ OSMO_ASSERT(msg);
+ OSMO_ASSERT(scl);
+
+ /* Empty list */
+ OSMO_ASSERT(scl->len >= 1);
+
+ msgb_put_u8(msg, GSM0808_IE_SPEECH_CODEC_LIST);
+ tlv_len = msgb_put(msg, 1);
+ old_tail = msg->tail;
+
+ for (i = 0; i < scl->len; i++) {
+ rc = enc_speech_codec(msg, &scl->codec[i]);
+ OSMO_ASSERT(rc >= 1);
+ bytes_used += rc;
+ OSMO_ASSERT(bytes_used <= 255);
+ }
+
+ *tlv_len = (uint8_t) (msg->tail - old_tail);
+ return *tlv_len + 2;
+}
+
+/* Decode Speech Codec list */
+int gsm0808_dec_speech_codec_list(struct gsm0808_speech_codec_list *scl,
+ const uint8_t *elem, uint8_t len)
+{
+ const uint8_t *old_elem = elem;
+ unsigned int i;
+ int rc;
+ uint8_t decoded = 0;
+
+ OSMO_ASSERT(scl);
+ if (!elem)
+ return -EINVAL;
+ if (len <= 0)
+ return -EINVAL;
+
+ memset(scl, 0, sizeof(*scl));
+
+ for (i = 0; i < ARRAY_SIZE(scl->codec); i++) {
+ if (len <= 0)
+ break;
+
+ rc = gsm0808_dec_speech_codec(&scl->codec[i], elem, len);
+ if (rc < 1)
+ return -EINVAL;
+
+ elem+=rc;
+ len -= rc;
+ decoded++;
+ }
+
+ scl->len = decoded;
+
+ /* Empty list */
+ if (decoded < 1) {
+ return -EINVAL;
+ }
+
+ return (int)(elem - old_elem);
+}