diff options
| author | Vadim Yanitskiy <axilirator@gmail.com> | 2018-10-04 04:58:56 +0700 |
|---|---|---|
| committer | Vadim Yanitskiy <axilirator@gmail.com> | 2018-11-21 11:03:10 +0700 |
| commit | 6168f6a49968eb4eece5637b04c35b32e3bc8112 (patch) | |
| tree | 5e710cb2a7e252ddcfd7d0c04e4c8bfc0c71eb8c /src | |
| parent | b5ae0ce8773bc5b18afa58f9876cc34fb5665d72 (diff) | |
layer23/l23sap.c: add Osmocom specific cbits for CBCH
CBCH logical channel is a bit similar to FACCH as there is no way
to indicate that it's exactly CBCH and not just a regular SDCCH.
There is nothing about CBCH stated in GSM 08.58, Chapter 9.3.1.
This change introduces Osmocom specific extensions for that.
Change-Id: I35e454c825481e6a390485ee042e384b31a08bf4
Diffstat (limited to 'src')
| -rw-r--r-- | src/host/layer23/src/common/l23sap.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/src/host/layer23/src/common/l23sap.c b/src/host/layer23/src/common/l23sap.c index 4560d236..fde55142 100644 --- a/src/host/layer23/src/common/l23sap.c +++ b/src/host/layer23/src/common/l23sap.c @@ -49,6 +49,30 @@ extern struct gsmtap_inst *gsmtap_inst; +/* Decoder for Osmocom specific chan_nr / link_id values (e.g. CBCH) */ +static int l23sap_dec_chan_nr_ext(uint8_t chan_nr, uint8_t link_id, + uint8_t *chan_type, uint8_t *chan_ts, uint8_t *chan_ss, + uint8_t *gsmtap_chan_type) +{ + uint8_t cbits = (chan_nr >> 3); + + if ((cbits & 0x1f) == 0x18) { + *chan_type = GSMTAP_CHANNEL_SDCCH4; + *chan_ss = 2; + if (gsmtap_chan_type) + *gsmtap_chan_type = GSMTAP_CHANNEL_CBCH51; + } else if ((cbits & 0x1f) == 0x19) { + *chan_type = GSMTAP_CHANNEL_SDCCH8; + if (gsmtap_chan_type) + *gsmtap_chan_type = GSMTAP_CHANNEL_CBCH51; + } else { + return -ENODEV; + } + + *chan_ts = chan_nr & 0x07; + return 0; +} + /* Safe wrapper around rsl_dec_chan_nr() */ static int l23sap_dec_chan_nr(uint8_t chan_nr, uint8_t link_id, uint8_t *chan_type, uint8_t *chan_ts, uint8_t *chan_ss, @@ -56,6 +80,13 @@ static int l23sap_dec_chan_nr(uint8_t chan_nr, uint8_t link_id, { int rc; + /* Attempt to decode Osmocom specific extensions */ + rc = l23sap_dec_chan_nr_ext(chan_nr, link_id, + chan_type, chan_ts, chan_ss, gsmtap_chan_type); + if (!rc) /* Successful decoding */ + return 0; + + /* Attempt to decode according to the specs */ rc = rsl_dec_chan_nr(chan_nr, chan_type, chan_ss, chan_ts); if (rc) { LOGP(DL23SAP, LOGL_ERROR, "Failed to decode logical channel " |