FreeCalypso > hg > gsm-net-reveng

comparison trau-decode/parse-efr.c @ 4:d9c095357c32

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
trau-parse: check and report EFR CRC
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 24 May 2024 09:16:35 +0000
parents
children bf5c9fb431b8
comparison
equal deleted inserted replaced
3:64b15810dc4c 4:d9c095357c32
1 /*
2 * This module implements the EFR decoding part of trau-parse.
3 */
4
5 #include <stdio.h>
6 #include <stdint.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <strings.h>
10 #include <gsm_efr.h>
11 #include "osmo_bits.h"
12
13 /*
14 * EFR TRAU parity
15 *
16 * g(x) = x^3 + x^1 + 1
17 */
18 static const struct osmo_crc8gen_code gsm0860_efr_crc3 = {
19 .bits = 3,
20 .poly = 0x3,
21 .init = 0x0,
22 .remainder = 0x7,
23 };
24
25 /* re-combine EFR parity bits */
26 static inline void efr_parity_bits_1(ubit_t *check_bits, const ubit_t *d_bits)
27 {
28 memcpy(check_bits + 0 , d_bits + 0, 22);
29 memcpy(check_bits + 22 , d_bits + 24, 3);
30 check_bits[25] = d_bits[28];
31 }
32
33 static inline void efr_parity_bits_2(ubit_t *check_bits, const ubit_t *d_bits)
34 {
35 memcpy(check_bits + 0 , d_bits + 42, 10);
36 memcpy(check_bits + 10 , d_bits + 90, 2);
37 }
38
39 static inline void efr_parity_bits_3(ubit_t *check_bits, const ubit_t *d_bits)
40 {
41 memcpy(check_bits + 0 , d_bits + 98, 5);
42 check_bits[5] = d_bits[104];
43 memcpy(check_bits + 6 , d_bits + 143, 2);
44 }
45
46 static inline void efr_parity_bits_4(ubit_t *check_bits, const ubit_t *d_bits)
47 {
48 memcpy(check_bits + 0 , d_bits + 151, 10);
49 memcpy(check_bits + 10 , d_bits + 199, 2);
50 }
51
52 static inline void efr_parity_bits_5(ubit_t *check_bits, const ubit_t *d_bits)
53 {
54 memcpy(check_bits + 0 , d_bits + 207, 5);
55 check_bits[5] = d_bits[213];
56 memcpy(check_bits + 6 , d_bits + 252, 2);
57 }
58
59 void
60 check_efr_crc(d_bits)
61 ubit_t *d_bits;
62 {
63 ubit_t check_bits[26];
64 int rc1, rc2, rc3, rc4, rc5;
65
66 efr_parity_bits_1(check_bits, d_bits);
67 rc1 = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 26,
68 d_bits + 39);
69 efr_parity_bits_2(check_bits, d_bits);
70 rc2 = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 12,
71 d_bits + 95);
72 efr_parity_bits_3(check_bits, d_bits);
73 rc3 = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 8,
74 d_bits + 148);
75 efr_parity_bits_4(check_bits, d_bits);
76 rc4 = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 12,
77 d_bits + 204);
78 efr_parity_bits_5(check_bits, d_bits);
79 rc5 = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 8,
80 d_bits + 257);
81 printf(" D1=%u CRC: %s %s %s %s %s\n", d_bits[0],
82 rc1 ? "bad" : "good", rc2 ? "bad" : "good",
83 rc3 ? "bad" : "good", rc4 ? "bad" : "good",
84 rc5 ? "bad" : "good");
85 }