FreeCalypso > hg > gsm-codec-lib
view libgsmefr/dec_create.c @ 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 | 23656d874524 |
| children |
line wrap: on
line source
/* * In this module we implement allocation and initialization * of state structures for our GSM EFR decoder. */ #include <stdlib.h> #include "gsm_efr.h" #include "typedef.h" #include "cnst.h" #include "dec_state.h" const unsigned EFR_decoder_state_size = sizeof(struct EFR_decoder_state); struct EFR_decoder_state *EFR_decoder_create(void) { struct EFR_decoder_state *st; st = malloc(sizeof(struct EFR_decoder_state)); if (st) EFR_decoder_reset(st); return st; }
