FreeCalypso > hg > gsm-codec-lib
view libgsmfrp/sidclass.c @ 20:93ed41fb4038
libgsmfrp/Makefile: add install
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sun, 20 Nov 2022 06:36:09 +0000 |
parents | 2b5770c715ee |
children |
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/* * gsmfr_preproc_sid_classify() utility function classifies * a GSM 06.10 frame in RTP encoding according to the rules * of GSM 06.31 (or 3GPP TS 46.031) section 6.1.1, judging it * as SID=0, SID=1 or SID=2. */ #include "gsm_fr_preproc.h" static const unsigned short sid_field_bits[95] = { 57, 58, 60, 61, 63, 64, 66, 67, 69, 70, 72, 73, 75, 76, 78, 79, 81, 82, 84, 85, 87, 88, 90, 91, 93, 94, 113, 114, 116, 117, 119, 120, 122, 123, 125, 126, 128, 129, 131, 132, 134, 135, 137, 138, 140, 141, 143, 144, 146, 147, 149, 150, 169, 170, 172, 173, 175, 176, 178, 179, 181, 182, 184, 185, 187, 188, 190, 191, 193, 194, 196, 197, 199, 200, 202, 203, 205, 206, 225, 226, 228, 229, 231, 232, 234, 235, 237, 240, 243, 246, 249, 252, 255, 258, 261 }; static inline int get_bit(const gsm_byte *frame, unsigned bitnum) { unsigned bytenum = bitnum >> 3; unsigned bit_in_byte = 7 - (bitnum & 7); unsigned bitmask = 1 << bit_in_byte; if (frame[bytenum] & bitmask) return 1; else return 0; } int gsmfr_preproc_sid_classify(const gsm_byte *frame) { unsigned idx, n; n = 0; for (idx = 0; idx < 95; idx++) { if (get_bit(frame, sid_field_bits[idx])) n++; if (n >= 16) return 0; } if (n < 2) return 2; else return 1; }