FreeCalypso > hg > gsm-codec-lib
changeset 604:54f0f1b74c25
libgsmhr1 TFO: require BFI=0 and SID=0 for homing
In order for a received frame to be recognized as DHF, we need
not only the correct bit pattern, but also BFI=0 and SID=0.
The BFI=0 requirement should be obvious, while the SID=0 requirement
is needed only for HR codec. With FR and EFR, SID classification
comes from the payload bits and no separate check is needed -
but in HR we get an out-of-band SID ternary flag. When SID=1,
no payload bits are used at all; when SID=2, we use only the first
33 bits of the payload. Therefore, it is proper to conditionalize
DHF acceptance on SID=0.
We already implemented this logic in the just finished full decoder;
now bring TFO code into agreement.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 04 Dec 2025 19:40:35 +0000 |
| parents | 27df1cef042c |
| children | 63f774192906 |
| files | libgsmhr1/tfo.c |
| diffstat | 1 files changed, 1 insertions(+), 1 deletions(-) [+] |
line wrap: on
line diff
--- a/libgsmhr1/tfo.c Thu Dec 04 19:05:38 2025 +0000 +++ b/libgsmhr1/tfo.c Thu Dec 04 19:40:35 2025 +0000 @@ -25,7 +25,7 @@ dl[19] = 1; } /* homing logic */ - if (!ul[18] && + if (ul[18] == 0 && ul[20] == 0 && !memcmp(ul, gsmhr_dhf_params, sizeof(int16_t) * GSMHR_NUM_PARAMS)) gsmhr_rxfe_reset(st); }