FreeCalypso > hg > gsm-codec-lib

annotate libgsmhr1/sid_detect.c @ 544:bd32bb1e8dab

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
doc/EFR-library-API: document malloc-alternative provision
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 03 Oct 2024 08:22:41 +0000
parents aaf4dec8bee0
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
494
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
1 /*
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
2 * The function in this module implements detection of perfect, error-free
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
3 * HRv1 SID frames in TS 101 318 raw packed format. If SID is detected,
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4 * the return value is 2: the code for valid SID per GSM 06.41.
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
5 */
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
6
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
7 #include <stdint.h>
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
8 #include <string.h>
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
9 #include "tw_gsmhr.h"
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
10
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11 int gsmhr_ts101318_is_perfect_sid(const uint8_t *payload)
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12 {
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13 static const uint8_t all_ff_bytes[9] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14 0xFF, 0xFF, 0xFF, 0xFF};
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
15
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
16 if ((payload[4] & 0x7F) != 0x7F)
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
17 return 0;
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
18 if (memcmp(payload + 5, all_ff_bytes, 9) == 0)
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
19 return 2;
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
20 else
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
21 return 0;
aaf4dec8bee0 libgsmhr1: implement perfect SID detection
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
22 }