1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
|
/*! \file gsm660.c
* GSM 06.60 - GSM EFR Codec. */
/*
* (C) 2010 Sylvain Munaut <tnt@246tNt.com>
*
* All Rights Reserved
*
* SPDX-License-Identifier: GPL-2.0+
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <stdint.h>
#include <stdbool.h>
#include <osmocom/core/bitvec.h>
#include <osmocom/core/utils.h>
#include <osmocom/codec/codec.h>
/* GSM EFR - subjective importance bit ordering */
/* This array encodes GSM 05.03 Table 6.
*
* It converts between serial parameter output (as described in
* GSM 06.60 Table 6 and GSM 05.03 Table 5) and the order needed
* before channel encoding. CRC poly and bit repetition must be
* applied prior to this table, as in GSM 05.03 3.1.1, to get 260
* bits from a 244 bits raw EFR frame.
*/
const uint16_t gsm660_bitorder[260] = {
38, 39, 40, 41, 42, 43, /* 0 -> LTP-LAG 1: b8..b3 */
145, 146, 147, 148, 149, 150, /* 6 -> LTP-LAG 3: b8..b3 */
93, 94, /* 12 -> LTP-LAG 2: b5..b4 */
200, 201, /* 14 -> LTP-LAG 4: b5..b4 */
47, /* 16 -> LTP-GAIN 1: b3 */
88, /* 17 -> FCB-GAIN 1: b4 */
99, /* 18 -> LTP-GAIN 2: b3 */
140, /* 19 -> FCB-GAIN 2: b4 */
44, /* 20 -> LTP-LAG 1: b2 */
151, /* 21 -> LTP-LAG 3: b2 */
95, /* 22 -> LTP-LAG 2: b3 */
202, /* 23 -> LTP-LAG 4: b3 */
1, 2, /* 24 -> LPC 1: b5..b4 */
7, /* 26 -> LPC 2: b7 */
9, /* 27 -> LPC 2: b5 */
17, 18, /* 28 -> LPC 3: b6..b5 */
23, /* 30 -> LPC 3: b0 */
45, 46, /* 31 -> LTP-LAG 1: b1..b0 */
152, 153, /* 33 -> LTP-LAG 3: b1..b0 */
96, /* 35 -> LTP-LAG 2: b2 */
203, /* 36 -> LTP-LAG 4: b2 */
3, 4, /* 37 -> LPC 1: b3..b2 */
10, 11, /* 39 -> LPC 2: b4..b3 */
15, /* 41 -> LPC 3: b8 */
8, /* 42 -> LPC 2: b6 */
5, 6, /* 43 -> LPC 1: b1..b0 */
12, /* 45 -> LPC 2: b2 */
16, /* 46 -> LPC 3: b7 */
19, /* 47 -> LPC 3: b4 */
97, /* 48 -> LTP-LAG 2: b1 */
204, /* 49 -> LTP-LAG 4: b1 */
0, /* 50 -> LPC 1: b6 */
13, 14, /* 51 -> LPC 2: b1..b0 */
20, /* 53 -> LPC 3: b3 */
24, 25, /* 54 -> LPC 4: b7..b6 */
27, /* 56 -> LPC 4: b4 */
154, /* 57 -> LTP-GAIN 3: b3 */
206, /* 58 -> LTP-GAIN 4: b3 */
195, /* 59 -> FCB-GAIN 3: b4 */
247, /* 60 -> FCB-GAIN 4: b4 */
89, /* 61 -> FCB-GAIN 1: b3 */
141, /* 62 -> FCB-GAIN 2: b3 */
196, /* 63 -> FCB-GAIN 3: b3 */
248, /* 64 -> FCB-GAIN 4: b3 */
252, 253, 254, 255, 256, 257, 258, 259, /* 65 -> CRC-POLY: b7..b0 */
48, /* 73 -> LTP-GAIN 1: b2 */
100, /* 74 -> LTP-GAIN 2: b2 */
155, /* 75 -> LTP-GAIN 3: b2 */
207, /* 76 -> LTP-GAIN 4: b2 */
21, 22, /* 77 -> LPC 3: b2..b1 */
26, /* 79 -> LPC 4: b5 */
28, /* 80 -> LPC 4: b3 */
51, /* 81 -> PULSE 1_1: b3 */
55, /* 82 -> PULSE 1_2: b3 */
59, /* 83 -> PULSE 1_3: b3 */
63, /* 84 -> PULSE 1_4: b3 */
67, /* 85 -> PULSE 1_5: b3 */
103, /* 86 -> PULSE 2_1: b3 */
107, /* 87 -> PULSE 2_2: b3 */
111, /* 88 -> PULSE 2_3: b3 */
115, /* 89 -> PULSE 2_4: b3 */
119, /* 90 -> PULSE 2_5: b3 */
158, /* 91 -> PULSE 3_1: b3 */
162, /* 92 -> PULSE 3_2: b3 */
166, /* 93 -> PULSE 3_3: b3 */
170, /* 94 -> PULSE 3_4: b3 */
174, /* 95 -> PULSE 3_5: b3 */
210, /* 96 -> PULSE 4_1: b3 */
214, /* 97 -> PULSE 4_2: b3 */
218, /* 98 -> PULSE 4_3: b3 */
222, /* 99 -> PULSE 4_4: b3 */
226, /* 100 -> PULSE 4_5: b3 */
90, /* 101 -> FCB-GAIN 1: b2 */
142, /* 102 -> FCB-GAIN 2: b2 */
197, /* 103 -> FCB-GAIN 3: b2 */
249, /* 104 -> FCB-GAIN 4: b2 */
49, /* 105 -> LTP-GAIN 1: b1 */
101, /* 106 -> LTP-GAIN 2: b1 */
156, /* 107 -> LTP-GAIN 3: b1 */
208, /* 108 -> LTP-GAIN 4: b1 */
29, 30, 31, /* 109 -> LPC 4: b2..b0 */
32, 33, 34, 35, /* 112 -> LPC 5: b5..b2 */
98, /* 116 -> LTP-LAG 2: b0 */
205, /* 117 -> LTP-LAG 4: b0 */
52, /* 118 -> PULSE 1_1: b2 */
56, /* 119 -> PULSE 1_2: b2 */
60, /* 120 -> PULSE 1_3: b2 */
64, /* 121 -> PULSE 1_4: b2 */
68, /* 122 -> PULSE 1_5: b2 */
104, /* 123 -> PULSE 2_1: b2 */
108, /* 124 -> PULSE 2_2: b2 */
112, /* 125 -> PULSE 2_3: b2 */
116, /* 126 -> PULSE 2_4: b2 */
120, /* 127 -> PULSE 2_5: b2 */
159, /* 128 -> PULSE 3_1: b2 */
163, /* 129 -> PULSE 3_2: b2 */
167, /* 130 -> PULSE 3_3: b2 */
171, /* 131 -> PULSE 3_4: b2 */
175, /* 132 -> PULSE 3_5: b2 */
211, /* 133 -> PULSE 4_1: b2 */
215, /* 134 -> PULSE 4_2: b2 */
219, /* 135 -> PULSE 4_3: b2 */
223, /* 136 -> PULSE 4_4: b2 */
227, /* 137 -> PULSE 4_5: b2 */
53, /* 138 -> PULSE 1_1: b1 */
57, /* 139 -> PULSE 1_2: b1 */
61, /* 140 -> PULSE 1_3: b1 */
65, /* 141 -> PULSE 1_4: b1 */
105, /* 142 -> PULSE 2_1: b1 */
109, /* 143 -> PULSE 2_2: b1 */
113, /* 144 -> PULSE 2_3: b1 */
117, /* 145 -> PULSE 2_4: b1 */
160, /* 146 -> PULSE 3_1: b1 */
164, /* 147 -> PULSE 3_2: b1 */
168, /* 148 -> PULSE 3_3: b1 */
172, /* 149 -> PULSE 3_4: b1 */
212, /* 150 -> PULSE 4_1: b1 */
220, /* 151 -> PULSE 4_3: b1 */
224, /* 152 -> PULSE 4_4: b1 */
91, /* 153 -> FCB-GAIN 1: b1 */
143, /* 154 -> FCB-GAIN 2: b1 */
198, /* 155 -> FCB-GAIN 3: b1 */
250, /* 156 -> FCB-GAIN 4: b1 */
50, /* 157 -> LTP-GAIN 1: b0 */
102, /* 158 -> LTP-GAIN 2: b0 */
157, /* 159 -> LTP-GAIN 3: b0 */
209, /* 160 -> LTP-GAIN 4: b0 */
92, /* 161 -> FCB-GAIN 1: b0 */
144, /* 162 -> FCB-GAIN 2: b0 */
199, /* 163 -> FCB-GAIN 3: b0 */
251, /* 164 -> FCB-GAIN 4: b0 */
54, /* 165 -> PULSE 1_1: b0 */
58, /* 166 -> PULSE 1_2: b0 */
62, /* 167 -> PULSE 1_3: b0 */
66, /* 168 -> PULSE 1_4: b0 */
106, /* 169 -> PULSE 2_1: b0 */
110, /* 170 -> PULSE 2_2: b0 */
114, /* 171 -> PULSE 2_3: b0 */
118, /* 172 -> PULSE 2_4: b0 */
161, /* 173 -> PULSE 3_1: b0 */
165, /* 174 -> PULSE 3_2: b0 */
169, /* 175 -> PULSE 3_3: b0 */
173, /* 176 -> PULSE 3_4: b0 */
213, /* 177 -> PULSE 4_1: b0 */
221, /* 178 -> PULSE 4_3: b0 */
225, /* 179 -> PULSE 4_4: b0 */
36, 37, /* 180 -> LPC 5: b1..b0 */
69, /* 182 -> PULSE 1_5: b1 */
71, 72, /* 183 -> PULSE 1_5: b1..b1 */
121, /* 185 -> PULSE 2_5: b1 */
123, 124, /* 186 -> PULSE 2_5: b1..b1 */
176, /* 188 -> PULSE 3_5: b1 */
178, 179, /* 189 -> PULSE 3_5: b1..b1 */
228, /* 191 -> PULSE 4_5: b1 */
230, 231, /* 192 -> PULSE 4_5: b1..b1 */
216, 217, /* 194 -> PULSE 4_2: b1..b0 */
70, /* 196 -> PULSE 1_5: b0 */
122, /* 197 -> PULSE 2_5: b0 */
177, /* 198 -> PULSE 3_5: b0 */
229, /* 199 -> PULSE 4_5: b0 */
73, /* 200 -> PULSE 1_6: b2 */
76, /* 201 -> PULSE 1_7: b2 */
79, /* 202 -> PULSE 1_8: b2 */
82, /* 203 -> PULSE 1_9: b2 */
85, /* 204 -> PULSE 1_10: b2 */
125, /* 205 -> PULSE 2_6: b2 */
128, /* 206 -> PULSE 2_7: b2 */
131, /* 207 -> PULSE 2_8: b2 */
134, /* 208 -> PULSE 2_9: b2 */
137, /* 209 -> PULSE 2_10: b2 */
180, /* 210 -> PULSE 3_6: b2 */
183, /* 211 -> PULSE 3_7: b2 */
186, /* 212 -> PULSE 3_8: b2 */
189, /* 213 -> PULSE 3_9: b2 */
192, /* 214 -> PULSE 3_10: b2 */
232, /* 215 -> PULSE 4_6: b2 */
235, /* 216 -> PULSE 4_7: b2 */
238, /* 217 -> PULSE 4_8: b2 */
241, /* 218 -> PULSE 4_9: b2 */
244, /* 219 -> PULSE 4_10: b2 */
74, /* 220 -> PULSE 1_6: b1 */
77, /* 221 -> PULSE 1_7: b1 */
80, /* 222 -> PULSE 1_8: b1 */
83, /* 223 -> PULSE 1_9: b1 */
86, /* 224 -> PULSE 1_10: b1 */
126, /* 225 -> PULSE 2_6: b1 */
129, /* 226 -> PULSE 2_7: b1 */
132, /* 227 -> PULSE 2_8: b1 */
135, /* 228 -> PULSE 2_9: b1 */
138, /* 229 -> PULSE 2_10: b1 */
181, /* 230 -> PULSE 3_6: b1 */
184, /* 231 -> PULSE 3_7: b1 */
187, /* 232 -> PULSE 3_8: b1 */
190, /* 233 -> PULSE 3_9: b1 */
193, /* 234 -> PULSE 3_10: b1 */
233, /* 235 -> PULSE 4_6: b1 */
236, /* 236 -> PULSE 4_7: b1 */
239, /* 237 -> PULSE 4_8: b1 */
242, /* 238 -> PULSE 4_9: b1 */
245, /* 239 -> PULSE 4_10: b1 */
75, /* 240 -> PULSE 1_6: b0 */
78, /* 241 -> PULSE 1_7: b0 */
81, /* 242 -> PULSE 1_8: b0 */
84, /* 243 -> PULSE 1_9: b0 */
87, /* 244 -> PULSE 1_10: b0 */
127, /* 245 -> PULSE 2_6: b0 */
130, /* 246 -> PULSE 2_7: b0 */
133, /* 247 -> PULSE 2_8: b0 */
136, /* 248 -> PULSE 2_9: b0 */
139, /* 249 -> PULSE 2_10: b0 */
182, /* 250 -> PULSE 3_6: b0 */
185, /* 251 -> PULSE 3_7: b0 */
188, /* 252 -> PULSE 3_8: b0 */
191, /* 253 -> PULSE 3_9: b0 */
194, /* 254 -> PULSE 3_10: b0 */
234, /* 255 -> PULSE 4_6: b0 */
237, /* 256 -> PULSE 4_7: b0 */
240, /* 257 -> PULSE 4_8: b0 */
243, /* 258 -> PULSE 4_9: b0 */
246, /* 259 -> PULSE 4_10: b0 */
};
static const uint8_t sid_code_word_bits[95] = {
/* bit numbers are relative to "pure" EFR frame beginning,
* not counting the signature bits. */
45, 46, 48, 49, 50, 51, 52, 53, 54, 55,
56, 57, 58, 59, 60, 61, 62, 63, 64, 65,
66, 67, 68, 94, 95, 96, 98, 99, 100, 101,
102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
112, 113, 114, 115, 116, 117, 118, 148, 149, 150,
151, 152, 153, 154, 155, 156, 157, 158, 159, 160,
161, 162, 163, 164, 165, 166, 167, 168, 169, 170,
171, 196, 197, 198, 199, 200, 201, 202, 203, 204,
205, 206, 207, 208, 209, 212, 213, 214, 215, 216,
217, 218, 219, 220, 221
};
/*! Check whether RTP frame contains EFR SID code word according to
* TS 101 318 §5.3.2
* \param[in] rtp_payload Buffer with RTP payload
* \param[in] payload_len Length of payload
* \returns true if code word is found, false otherwise
*/
bool osmo_efr_check_sid(const uint8_t *rtp_payload, size_t payload_len)
{
struct bitvec bv;
uint16_t i;
/* signature does not match Enhanced Full Rate SID */
if ((rtp_payload[0] >> 4) != 0xC)
return false;
bv.data = (uint8_t *) rtp_payload;
bv.data_len = payload_len;
/* code word is all 1 at given bits */
for (i = 0; i < ARRAY_SIZE(sid_code_word_bits); i++) {
if (bitvec_get_bit_pos(&bv, sid_code_word_bits[i]+4) != ONE)
return false;
}
return true;
}
/*! Classify potentially-SID EFR codec frame in RTP format according
* to the rules of GSM 06.81 §6.1.1
* \param[in] rtp_payload Buffer with RTP payload
* \returns enum osmo_gsm631_sid_class, with symbolic values
* OSMO_GSM631_SID_CLASS_SPEECH, OSMO_GSM631_SID_CLASS_INVALID or
* OSMO_GSM631_SID_CLASS_VALID corresponding to the 3 possible bit-counting
* classifications prescribed by the spec.
*
* Differences between the more familiar osmo_efr_check_sid() and the present
* function are:
*
* 1. osmo_efr_check_sid() returns true only if the SID frame is absolutely
* perfect, with all 95 bits of the SID code word set. However, the
* rules of GSM 06.81 §6.1.1 allow up to one bit to be in error,
* and the frame is still accepted as valid SID.
*
* 2. The third possible state of invalid SID is not handled at all by the
* simpler osmo_efr_check_sid() function.
*
* 3. osmo_efr_check_sid() includes a check for 0xC RTP signature, and returns
* false if that signature nibble is wrong. That check is not included
* in the present version because there is no place for it in the
* ETSI-prescribed classification, it is neither speech nor SID. The
* assumption is that this function is used to classify the bit content
* of received codec frames, not their RTP encoding - the latter needs
* to be validated beforehand.
*
* Which function should one use? The answer depends on the specific
* circumstances, and needs to be addressed on a case-by-case basis.
*/
enum osmo_gsm631_sid_class osmo_efr_sid_classify(const uint8_t *rtp_payload)
{
struct bitvec bv;
uint16_t i, n;
bv.data = (uint8_t *) rtp_payload;
bv.data_len = GSM_EFR_BYTES;
/* count not-SID-matching bits per the spec */
n = 0;
for (i = 0; i < ARRAY_SIZE(sid_code_word_bits); i++) {
if (bitvec_get_bit_pos(&bv, sid_code_word_bits[i]+4) != ONE)
n++;
if (n >= 16)
return OSMO_GSM631_SID_CLASS_SPEECH;
}
if (n >= 2)
return OSMO_GSM631_SID_CLASS_INVALID;
else
return OSMO_GSM631_SID_CLASS_VALID;
}
/*! Reset the SID field of a potentially corrupted, but still valid GSM-EFR
* SID frame in RTP encoding to its pristine state (full SID code word).
* \param[in] rtp_payload Buffer with RTP payload - must be writable!
*
* Per GSM 06.62 section 5.3, a freshly minted SID frame consists of 58 bits
* of comfort noise parameters (LSF and 4 times fixed codebook gain), 95 bits
* of SID code word (all 1s) and 91 unused bits (all 0s). Network elements
* that receive SID frames from call leg A uplink and need to retransmit them
* on leg B downlink should "rejuvenate" received SID frames prior to
* retransmission by resetting the SID field to its pristine state of all 1s;
* this function does the job.
*
* Potential TODO: it would be nice to also zero out the remaining 91 bits
* which the spec leaves as reserved, clearing out leg A radio bit errors -
* but do we really need to?
*/
void osmo_efr_sid_reset(uint8_t *rtp_payload)
{
/* set all 95 SID code word bits to 1 */
rtp_payload[6] |= 0x6F;
rtp_payload[7] = 0xFF;
rtp_payload[8] = 0xFF;
rtp_payload[9] |= 0x80;
rtp_payload[12] |= 0x3B;
rtp_payload[13] = 0xFF;
rtp_payload[14] = 0xFF;
rtp_payload[15] |= 0xE0;
rtp_payload[19] = 0xFF;
rtp_payload[20] = 0xFF;
rtp_payload[21] = 0xFF;
rtp_payload[25] = 0xFF;
rtp_payload[26] |= 0xFC;
rtp_payload[27] = 0xFF;
rtp_payload[28] |= 0xC0;
}
/*! Preen potentially-SID EFR codec frame in RTP format, ensuring that it is
* either a speech frame or a valid SID, and if the latter, making it a
* perfect, error-free SID frame.
* \param[in] rtp_payload Buffer with RTP payload - must be writable!
* \returns true if the frame is good, false otherwise
*/
bool osmo_efr_sid_preen(uint8_t *rtp_payload)
{
enum osmo_gsm631_sid_class sidc;
sidc = osmo_efr_sid_classify(rtp_payload);
switch (sidc) {
case OSMO_GSM631_SID_CLASS_SPEECH:
return true;
case OSMO_GSM631_SID_CLASS_INVALID:
return false;
case OSMO_GSM631_SID_CLASS_VALID:
/* "Rejuvenate" this SID frame, correcting any errors */
osmo_efr_sid_reset(rtp_payload);
return true;
default:
/* There are only 3 possible SID classifications per GSM 06.81
* section 6.1.1, thus any other return value is a grave error
* in the code. */
OSMO_ASSERT(0);
}
}
|
