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comparison libgsmhr1/sid_detect.c @ 494:aaf4dec8bee0

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libgsmhr1: implement perfect SID detection
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 17 Jun 2024 23:14:19 +0000
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493:dc7249923b3a 494:aaf4dec8bee0
1 /*
2 * The function in this module implements detection of perfect, error-free
3 * HRv1 SID frames in TS 101 318 raw packed format. If SID is detected,
4 * the return value is 2: the code for valid SID per GSM 06.41.
5 */
6
7 #include <stdint.h>
8 #include <string.h>
9 #include "tw_gsmhr.h"
10
11 int gsmhr_ts101318_is_perfect_sid(const uint8_t *payload)
12 {
13 static const uint8_t all_ff_bytes[9] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
14 0xFF, 0xFF, 0xFF, 0xFF};
15
16 if ((payload[4] & 0x7F) != 0x7F)
17 return 0;
18 if (memcmp(payload + 5, all_ff_bytes, 9) == 0)
19 return 2;
20 else
21 return 0;
22 }