annotate libgsmefr/sid_class.c @ 585:3c6bf0d26ee7 default tip

TW-TS-005 reader: fix maximum line length bug TW-TS-005 section 4.1 states: The maximum allowed length of each line is 80 characters, not including the OS-specific newline encoding. The implementation of this line length limit in the TW-TS-005 hex file reader function in the present suite was wrong, such that lines of the full maximum length could not be read. Fix it. Note that this bug affects comment lines too, not just actual RTP payloads. Neither Annex A nor Annex B features an RTP payload format that goes to the maximum of 40 bytes, but if a comment line goes to the maximum allowed length of 80 characters not including the terminating newline, the bug will be triggered, necessitating the present fix.
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 25 Feb 2025 07:49:28 +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 }