FreeCalypso > hg > gsm-codec-lib

annotate libgsmefr/sid_class.c @ 282:9ee8ad3d4d30

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frtest: rm gsmfr-hand-test and gsmfr-max-out utils These hack programs were never properly documented and were written only as part of a debug chase, in pursuit of a bug that ultimately turned out to be in our then-hacky patch to osmo-bts-sysmo, before beginning of proper patches in Osmocom. These hack programs need to be dropped from the present sw package because they depend on old libgsm, and we are eliminating that dependency.
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 14 Apr 2024 05:44:47 +0000
parents b5726d659915
children
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1 /*
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2 * EFR_sid_classify() utility function classifies an EFR frame
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3 * in RTP encoding according to the rules of GSM 06.81 section 6.1.1,
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4 * judging it as SID=0, SID=1 or SID=2.
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5 */
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6
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7 #include "gsm_efr.h"
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8
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9 static const uint8_t SID_codeword_bit_idx[95] =
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10 {
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21 };
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23 static inline int get_bit(const uint8_t *frame, unsigned bitnum)
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24 {
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25 unsigned bytenum = bitnum >> 3;
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26 unsigned bit_in_byte = 7 - (bitnum & 7);
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27 unsigned bitmask = 1 << bit_in_byte;
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29 if (frame[bytenum] & bitmask)
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30 return 1;
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31 else
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32 return 0;
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33 }
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34
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35 int EFR_sid_classify(const uint8_t *frame)
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36 {
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37 unsigned idx, n;
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39 n = 0;
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40 for (idx = 0; idx < 95; idx++) {
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41 if (!get_bit(frame, SID_codeword_bit_idx[idx] + 4))
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42 n++;
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43 if (n >= 16)
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44 return 0;
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45 }
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46 if (n < 2)
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47 return 2;
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48 else
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49 return 1;
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50 }