FreeCalypso > hg > gsm-net-reveng

comparison trau-decode/parse-amr.c @ 79:8c1f20e845a1

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
trau-parse: more thorough AMR decoding CRC verification has been implemented for No_Speech frames, but not for the 8 speech modes yet.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 08 Feb 2025 09:13:30 +0000
parents 00fd38c7c8fe
children 58dfdb2fc6df
comparison
equal deleted inserted replaced
78:00fd38c7c8fe 79:8c1f20e845a1
1 /* 1 /*
2 * This module contains a bit of code that has been factored out of 2 * Here we implement parsing/decoding of AMR frames as in 3GPP TS 48.060
3 * trau-parse program; it handles AMR frames. 3 * section 5.5.1.2, striving to decode and display as much as we can.
4 */ 4 */
5 5
6 #include <stdio.h> 6 #include <stdio.h>
7 #include <stdint.h> 7 #include <stdint.h>
8 #include <stdlib.h> 8 #include <stdlib.h>
9 #include <string.h> 9 #include <string.h>
10 #include <strings.h> 10 #include <strings.h>
11 #include "osmo_bits.h"
12
13 /*
14 * AMR TRAU parity (same as EFR)
15 *
16 * g(x) = x^3 + x^1 + 1
17 */
18 static const struct osmo_crc8gen_code gsm0860_amr_crc3 = {
19 .bits = 3,
20 .poly = 0x3,
21 .init = 0x0,
22 .remainder = 0x7,
23 };
24
25 static int saved_mode, saved_mode_valid;
26
27 static char *fclass_names[4] = {
28 "No_Speech", "Speech_Bad", "Speech_Degraded", "Speech_Good"
29 };
30
31 static char *nospch_class_names[8] = {
32 "No_Data", "invalid", "invalid", "invalid",
33 "Sid_Bad", "Sid_Update", "Onset", "Sid_First"
34 };
11 35
12 static unsigned 36 static unsigned
13 bits_to_num(bits, nbits) 37 bits_to_num(bits, nbits)
14 uint8_t *bits; 38 ubit_t *bits;
15 unsigned nbits; 39 unsigned nbits;
16 { 40 {
17 unsigned accum; 41 unsigned accum;
18 unsigned n; 42 unsigned n;
19 43
25 bits++; 49 bits++;
26 } 50 }
27 return accum; 51 return accum;
28 } 52 }
29 53
54 static void
55 decode_mode_0(c_bits, d_bits)
56 ubit_t *c_bits, *d_bits;
57 {
58 }
59
60 static void
61 decode_mode_1(c_bits, d_bits)
62 ubit_t *c_bits, *d_bits;
63 {
64 }
65
66 static void
67 decode_mode_2(c_bits, d_bits)
68 ubit_t *c_bits, *d_bits;
69 {
70 }
71
72 static void
73 decode_mode_3(c_bits, d_bits)
74 ubit_t *c_bits, *d_bits;
75 {
76 }
77
78 static void
79 decode_mode_4(c_bits, d_bits)
80 ubit_t *c_bits, *d_bits;
81 {
82 }
83
84 static void
85 decode_mode_5(c_bits, d_bits)
86 ubit_t *c_bits, *d_bits;
87 {
88 }
89
90 static void
91 decode_mode_6(c_bits, d_bits)
92 ubit_t *c_bits, *d_bits;
93 {
94 }
95
96 static void
97 decode_mode_7(c_bits, d_bits)
98 ubit_t *c_bits, *d_bits;
99 {
100 }
101
102 static void (*per_mode_decode[8])() = {
103 decode_mode_0,
104 decode_mode_1,
105 decode_mode_2,
106 decode_mode_3,
107 decode_mode_4,
108 decode_mode_5,
109 decode_mode_6,
110 decode_mode_7
111 };
112
113 static void
114 decode_speech_frame(c_bits, d_bits, cm_hdr)
115 ubit_t *c_bits, *d_bits;
116 unsigned cm_hdr;
117 {
118 unsigned mode;
119
120 if (c_bits[11]) {
121 if (!saved_mode_valid) {
122 printf(" Mode unknown, cannot decode\n");
123 return;
124 }
125 mode = saved_mode;
126 saved_mode_valid = 0;
127 } else {
128 mode = cm_hdr;
129 saved_mode = mode;
130 saved_mode_valid = 1;
131 }
132 printf(" Decoding per speech mode %u\n", mode);
133 per_mode_decode[mode](c_bits, d_bits);
134 }
135
136 static void
137 decode_nospeech_frame(c_bits, d_bits)
138 ubit_t *c_bits, *d_bits;
139 {
140 ubit_t crc_collect[25 + 61];
141 int crc_stat;
142
143 printf(" No_Spch_Class=%u%u%u (%s) CMI=%u CMR=%u\n",
144 d_bits[31], d_bits[32], d_bits[33],
145 nospch_class_names[bits_to_num(d_bits + 31, 3)],
146 bits_to_num(d_bits + 34, 3), bits_to_num(d_bits + 37, 3));
147 printf(" PAB=%u TAE=%u%u\n", d_bits[40], d_bits[41], d_bits[42]);
148 bcopy(c_bits, crc_collect, 25);
149 bcopy(d_bits + 31, crc_collect + 25, 61);
150 crc_stat = osmo_crc8gen_check_bits(&gsm0860_amr_crc3, crc_collect,
151 25 + 61, d_bits + 92);
152 printf(" CRC %s\n", crc_stat ? "bad" : "good");
153 if (crc_stat) {
154 saved_mode_valid = 0;
155 } else {
156 saved_mode = bits_to_num(d_bits + 34, 3);
157 saved_mode_valid = 1;
158 }
159 }
160
30 void 161 void
31 print_amr_frame(frame_bits) 162 print_amr_frame(frame_bits)
32 uint8_t *frame_bits; 163 uint8_t *frame_bits;
33 { 164 {
34 unsigned c6_11; 165 ubit_t c_bits[25], d_bits[256];
35 166 uint8_t fclass, cm_hdr;
36 c6_11 = bits_to_num(frame_bits + 22, 6); 167
37 printf(" C6-C11: %u\n", c6_11); 168 bcopy(frame_bits + 17, c_bits, 15);
169 bcopy(frame_bits + 33, c_bits + 15, 10);
170 bcopy(frame_bits + 43, d_bits, 5);
171 bcopy(frame_bits + 49, d_bits + 5, 15);
172 bcopy(frame_bits + 65, d_bits + 20, 15);
173 bcopy(frame_bits + 81, d_bits + 35, 15);
174 bcopy(frame_bits + 97, d_bits + 50, 15);
175 bcopy(frame_bits + 113, d_bits + 65, 15);
176 bcopy(frame_bits + 129, d_bits + 80, 15);
177 bcopy(frame_bits + 145, d_bits + 95, 15);
178 bcopy(frame_bits + 161, d_bits + 110, 15);
179 bcopy(frame_bits + 177, d_bits + 125, 15);
180 bcopy(frame_bits + 193, d_bits + 140, 15);
181 bcopy(frame_bits + 209, d_bits + 155, 15);
182 bcopy(frame_bits + 225, d_bits + 170, 15);
183 bcopy(frame_bits + 241, d_bits + 185, 15);
184 bcopy(frame_bits + 257, d_bits + 200, 15);
185 bcopy(frame_bits + 273, d_bits + 215, 15);
186 bcopy(frame_bits + 289, d_bits + 230, 15);
187 bcopy(frame_bits + 305, d_bits + 245, 11);
188
189 printf(" C6-C11: %u\n", bits_to_num(c_bits + 5, 6));
38 printf(" RIF=%u C13=%u Config_Prot=%u%u%u Msg_No=%u%u\n", 190 printf(" RIF=%u C13=%u Config_Prot=%u%u%u Msg_No=%u%u\n",
39 frame_bits[28], frame_bits[29], frame_bits[30], 191 c_bits[11], c_bits[12], c_bits[13], c_bits[14], c_bits[15],
40 frame_bits[31], frame_bits[33], frame_bits[34], 192 c_bits[16], c_bits[17]);
41 frame_bits[35]); 193 fclass = bits_to_num(c_bits + 20, 2);
42 printf(" DTXd=%u TFOE=%u FClass=%u%u CMI/CMR=%u%u%u\n", 194 cm_hdr = bits_to_num(c_bits + 22, 3);
43 frame_bits[36], frame_bits[37], frame_bits[38], 195 printf(" DTXd=%u TFOE=%u FClass=%u%u (%s) %s=%u\n",
44 frame_bits[39], frame_bits[40], frame_bits[41], 196 c_bits[18], c_bits[19], c_bits[20], c_bits[21],
45 frame_bits[42]); 197 fclass_names[fclass], c_bits[11] ? "CMR" : "CMI", cm_hdr);
46 if (!frame_bits[38] && !frame_bits[39]) 198 if (fclass)
47 printf(" No_Spch_Class=%u%u%u CMI=%u%u%u CMR=%u%u%u\n", 199 decode_speech_frame(c_bits, d_bits, cm_hdr);
48 frame_bits[76], frame_bits[77], frame_bits[78], 200 else
49 frame_bits[79], frame_bits[81], frame_bits[82], 201 decode_nospeech_frame(c_bits, d_bits);
50 frame_bits[83], frame_bits[84], frame_bits[85]);
51 printf(" T1=%u T2=%u T3=%u T4=%u\n", frame_bits[316], 202 printf(" T1=%u T2=%u T3=%u T4=%u\n", frame_bits[316],
52 frame_bits[317], frame_bits[318], frame_bits[319]); 203 frame_bits[317], frame_bits[318], frame_bits[319]);
53 } 204 }