pespin has submitted this change. ( https://gerrit.osmocom.org/c/libosmo-netif/+/30758 )

Change subject: amr: Clarify size of AMR BWE header and ToC ......................................................................

amr: Clarify size of AMR BWE header and ToC

Change-Id: I34c76b18ee45e12dba92864715e8ef91e6de3b01 --- M include/osmocom/netif/amr.h M src/amr.c 2 files changed, 8 insertions(+), 4 deletions(-)

Approvals: Jenkins Builder: Verified laforge: Looks good to me, approved fixeria: Looks good to me, approved

diff --git a/include/osmocom/netif/amr.h b/include/osmocom/netif/amr.h index e8f08d4..9b8fb79 100644 --- a/include/osmocom/netif/amr.h +++ b/include/osmocom/netif/amr.h @@ -43,6 +43,9 @@ uint8_t data[0]; } __attribute__((packed));

+/* See diagram above: CMR (4) + F (1) + FT (4) + Q (1) = 10 */ +#define AMR_HDR_BWE_LEN_BITS 10 + /* * 4.4. Octet-aligned Mode: * diff --git a/src/amr.c b/src/amr.c index e4f0dd8..18e699c 100644 --- a/src/amr.c +++ b/src/amr.c @@ -188,7 +188,7 @@ }

/* Calculate new payload length */ - bwe_payload_len = (10 + osmo_amr_bits(ft) + 7) / 8; + bwe_payload_len = (AMR_HDR_BWE_LEN_BITS + osmo_amr_bits(ft) + 7) / 8;

return bwe_payload_len; } @@ -266,7 +266,8 @@ amr_speech_len_bits = osmo_amr_bits(ft); amr_speech_len_bytes = osmo_amr_bytes(ft);

- required_len_bits = amr_speech_len_bits + 10; /* shift of 10 bits */ + /* shift of AMR_HDR_BWE_LEN_BITS (10) bits, aka remove BWE Hdr + ToC: */ + required_len_bits = AMR_HDR_BWE_LEN_BITS + amr_speech_len_bits; if (payload_len < (required_len_bits + 7)/8) return -1;

@@ -288,7 +289,7 @@ int osmo_amr_iuup_to_bwe(uint8_t *payload, unsigned int payload_len, unsigned int payload_maxlen) { - /* shift all bits by 10 */ + /* shift all bits by AMR_HDR_BWE_LEN_BITS (10) */ unsigned int i, required_len_bits, required_len_bytes;

int ft = osmo_amr_bytes_to_ft(payload_len); @@ -303,7 +304,7 @@ i = payload_len + 1; payload[i] = (payload[i - 2] << 6); for (i = payload_len; i >= 2; i--) { - /* we have to shift the payload by 10 bits to get only the Class A, B, C bits */ + /* we have to shift the payload by AMR_HDR_BWE_LEN_BITS (10) bits to prepend BWE Hdr + ToC */ payload[i] = (payload[i - 1] >> 2) | (payload[i - 2] << 6); } payload[i] = (payload[i - 1] >> 2);