diff options
| author | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2020-06-11 01:04:44 +0700 |
|---|---|---|
| committer | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2020-06-11 01:29:40 +0700 |
| commit | 81b610ea2c0c3580d172b34179d7a5486a31df29 (patch) | |
| tree | c01c36ce46fec6c86ed2dc0c93813ae19452822c | |
| parent | 07b6487c5ac11a95e4bd0e11c6c6c65437776776 (diff) | |
bts: fix send_gsmtap_rach(): properly pack 11 bit RA
According to 3GPP TS 44.004, section 7.4a, two alternative RACH
block formats are specified: 8 bit (1 octet) and 11 bit. The
bit order is LSB (right to left), byte order is MSB.
In PCUIF RACH.ind structure (see gsm_pcu_if_rach_ind) we use
a field of type uint16_t to store RA values regardles of the
block format. Thus when packing it to bytes, we cannot just
cast uint16_t* to uint8_t*, we need to do some bit shifting.
Change-Id: I08a0a908f855b0d8a002df732e02781126d27dfb
| -rw-r--r-- | src/bts.cpp | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/src/bts.cpp b/src/bts.cpp index 0482168d..617cd785 100644 --- a/src/bts.cpp +++ b/src/bts.cpp @@ -434,9 +434,21 @@ void BTS::send_gsmtap_rach(enum pcu_gsmtap_category categ, uint8_t channel, const struct rach_ind_params *rip) { struct pcu_l1_meas meas; + uint8_t ra_buf[2]; + + /* 3GPP TS 44.004 defines 11 bit RA as follows: xxxx xxxx .... .yyy + * On the PCUIF, we get 16 bit machne dependent number (LE/BE) + * Over GSMTAP we send the following: xxxx xxxx yyy. .... + * This simplifies parsing in Wireshark using its CSN.1 codec. */ + if (rip->is_11bit) { + ra_buf[0] = (uint8_t) ((rip->ra >> 3) & 0xff); + ra_buf[1] = (uint8_t) ((rip->ra << 5) & 0xff); + } else { + ra_buf[0] = (uint8_t) (rip->ra & 0xff); + } + send_gsmtap_meas(categ, true, rip->trx_nr, rip->ts_nr, channel, - rfn_to_fn(rip->rfn), (uint8_t *) &rip->ra, - /* TODO: properly pack 11 bit RA */ + rfn_to_fn(rip->rfn), ra_buf, rip->is_11bit ? 2 : 1, &meas); } |