FreeCalypso > hg > gsm-codec-lib
view hrutil/read-cod.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 | bb36ef735f25 |
| children |
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/* * In this module we implement the utility function for reading ETSI * GSM-HR *.cod files in either LE or BE format. */ #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <strings.h> #include "../libgsmhr1/tw_gsmhr.h" read_cod_frame(inf, big_endian, params, filename_for_errs, frame_no) FILE *inf; int16_t *params; char *filename_for_errs; unsigned frame_no; { uint8_t file_bytes[GSMHR_NUM_PARAMS_ENC * 2], *sp; int cc; unsigned n; uint16_t val; cc = fread(file_bytes, 2, GSMHR_NUM_PARAMS_ENC, inf); if (cc == 0) return 0; if (cc != GSMHR_NUM_PARAMS_ENC) { fprintf(stderr, "error: short read from %s\n", filename_for_errs); exit(1); } sp = file_bytes; for (n = 0; n < GSMHR_NUM_PARAMS_ENC; n++) { if (big_endian) val = ((uint16_t) sp[0] << 8) | ((uint16_t) sp[1]); else val = ((uint16_t) sp[1] << 8) | ((uint16_t) sp[0]); params[n] = val; sp += 2; } if (gsmhr_check_encoder_params(params) < 0) { fprintf(stderr, "error in %s frame #%u: wrong format or wrong endian\n", filename_for_errs, frame_no); exit(1); } return 1; }
