Philipp Maier | 898c9c6 | 2020-02-06 14:25:01 +0100 | [diff] [blame] | 1 | /* |
| 2 | * (C) 2020 by sysmocom - s.f.m.c. GmbH, Author: Philipp Maier |
| 3 | * All Rights Reserved |
| 4 | * |
| 5 | * SPDX-License-Identifier: GPL-2.0+ |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version 2 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | * |
| 12 | * This program is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | * GNU General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License |
| 18 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 19 | * |
| 20 | */ |
| 21 | |
| 22 | #include <stdio.h> |
| 23 | #include <stdint.h> |
| 24 | #include <string.h> |
| 25 | #include <stdlib.h> |
| 26 | #include <errno.h> |
| 27 | |
| 28 | #include <osmocom/core/bits.h> |
| 29 | #include <osmocom/core/conv.h> |
| 30 | #include <osmocom/core/utils.h> |
| 31 | #include <osmocom/coding/gsm0503_amr_dtx.h> |
| 32 | #include <osmocom/coding/gsm0503_parity.h> |
| 33 | #include <osmocom/gsm/gsm0503.h> |
| 34 | |
| 35 | /* See also: 3GPP TS 05.03, chapter 3.10.1.3, 3.10.5.2 Identification marker */ |
| 36 | static const ubit_t id_marker_1[] = { 1, 0, 1, 1, 0, 0, 0, 0, 1 }; |
| 37 | |
| 38 | /* See also: 3GPP TS 05.03, chapter 3.9.1.3, 3.10.2.2, 3.10.2.2 Identification marker */ |
| 39 | static const ubit_t id_marker_0[] = { 0, 1, 0, 0, 1, 1, 1, 1, 0 }; |
| 40 | |
| 41 | /* See also: 3GPP TS 05.03, chapter 3.9 Adaptive multi rate speech channel at full rate (TCH/AFS) */ |
| 42 | static const ubit_t codec_mode_1_sid[] = { 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0 }; |
| 43 | static const ubit_t codec_mode_2_sid[] = { 0, 0, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0 }; |
| 44 | static const ubit_t codec_mode_3_sid[] = { 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1 }; |
| 45 | static const ubit_t codec_mode_4_sid[] = { 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1 }; |
| 46 | |
| 47 | const struct value_string gsm0503_amr_dtx_frame_names[] = { |
| 48 | { AFS_SID_FIRST, "AFS_SID_FIRST" }, |
| 49 | { AFS_SID_UPDATE, "AFS_SID_UPDATE" }, |
| 50 | { AFS_ONSET, "AFS_ONSET" }, |
| 51 | { AHS_SID_UPDATE, "AHS_SID_UPDATE" }, |
| 52 | { AHS_SID_FIRST_P1, "AHS_SID_FIRST_P1" }, |
| 53 | { AHS_SID_FIRST_P2, "AHS_SID_FIRST_P2" }, |
| 54 | { AHS_ONSET, "AHS_ONSET" }, |
| 55 | { AHS_SID_FIRST_INH, "AHS_SID_FIRST_INH" }, |
| 56 | { AHS_SID_UPDATE_INH, "AHS_SID_UPDATE_INH" }, |
| 57 | { AMR_OTHER, "NON DTX FRAME (OTHER)" }, |
| 58 | { 0, NULL } |
| 59 | }; |
| 60 | |
| 61 | static bool detect_afs_id_marker(int *n_errors, int *n_bits_total, const ubit_t * ubits, uint8_t offset, uint8_t count, |
| 62 | const ubit_t * id_marker, uint8_t id_marker_len) |
| 63 | { |
| 64 | unsigned int i, k; |
| 65 | unsigned int id_bit_nr = 0; |
| 66 | int errors = 0; |
| 67 | int bits = 0; |
| 68 | |
| 69 | /* Override coded in-band data */ |
| 70 | ubits += offset; |
| 71 | |
| 72 | /* Check for identification marker bits */ |
| 73 | for (i = 0; i < count; i++) { |
| 74 | for (k = 0; k < 4; k++) { |
| 75 | if (id_marker[id_bit_nr % id_marker_len] != *ubits) |
| 76 | errors++; |
| 77 | id_bit_nr++; |
| 78 | ubits++; |
| 79 | bits++; |
| 80 | } |
| 81 | |
| 82 | /* Jump to the next block of 4 bits */ |
| 83 | ubits += 4; |
| 84 | } |
| 85 | |
| 86 | *n_errors = errors; |
| 87 | *n_bits_total = bits; |
| 88 | |
| 89 | /* Tolerate up to 1/8 errornous bits */ |
| 90 | return *n_errors < *n_bits_total / 8; |
| 91 | } |
| 92 | |
| 93 | static bool detect_ahs_id_marker(int *n_errors, int *n_bits_total, const ubit_t * ubits, const ubit_t * id_marker) |
| 94 | { |
| 95 | unsigned int i, k; |
| 96 | int errors = 0; |
| 97 | int bits = 0; |
| 98 | |
| 99 | /* Override coded in-band data */ |
| 100 | ubits += 16; |
| 101 | |
| 102 | /* Check first identification marker bits (23*9 bits) */ |
| 103 | for (i = 0; i < 23; i++) { |
| 104 | for (k = 0; k < 9; k++) { |
| 105 | if (id_marker[k] != *ubits) |
| 106 | errors++; |
| 107 | ubits++; |
| 108 | bits++; |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | /* Check remaining identification marker bits (5 bits) */ |
| 113 | for (k = 0; k < 5; k++) { |
| 114 | if (id_marker[k] != *ubits) |
| 115 | errors++; |
| 116 | ubits++; |
| 117 | bits++; |
| 118 | } |
| 119 | |
| 120 | *n_errors = errors; |
| 121 | *n_bits_total = bits; |
| 122 | |
| 123 | /* Tolerate up to 1/8 errornous bits */ |
| 124 | return *n_errors < *n_bits_total / 8; |
| 125 | } |
| 126 | |
| 127 | static bool detect_interleaved_ahs_id_marker(int *n_errors, int *n_bits_total, const ubit_t * ubits, uint8_t offset, |
| 128 | uint8_t n_bits, const ubit_t * id_marker, uint8_t id_marker_len) |
| 129 | { |
| 130 | unsigned int i, k; |
| 131 | int errors = 0; |
| 132 | int bits = 0; |
| 133 | uint8_t full_rounds = n_bits / id_marker_len; |
| 134 | uint8_t remainder = n_bits % id_marker_len; |
| 135 | |
| 136 | /* Override coded in-band data */ |
| 137 | ubits += offset; |
| 138 | |
| 139 | /* Check first identification marker bits (23*9 bits) */ |
| 140 | for (i = 0; i < full_rounds; i++) { |
| 141 | for (k = 0; k < id_marker_len; k++) { |
| 142 | if (id_marker[k] != *ubits) |
| 143 | errors++; |
| 144 | ubits += 2; |
| 145 | bits++; |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | /* Check remaining identification marker bits (5 bits) */ |
| 150 | for (k = 0; k < remainder; k++) { |
| 151 | if (id_marker[k] != *ubits) |
| 152 | errors++; |
| 153 | ubits += 2; |
| 154 | bits++; |
| 155 | } |
| 156 | |
| 157 | *n_errors = errors; |
| 158 | *n_bits_total = bits; |
| 159 | |
| 160 | /* Tolerate up to 1/8 errornous bits */ |
| 161 | return *n_errors < *n_bits_total / 8; |
| 162 | } |
| 163 | |
| 164 | /* Detect a an FR AMR SID_FIRST frame by its identifcation marker */ |
| 165 | static bool detect_afs_sid_first(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 166 | { |
| 167 | return detect_afs_id_marker(n_errors, n_bits_total, ubits, 32, 53, id_marker_0, 9); |
| 168 | } |
| 169 | |
| 170 | /* Detect an FR AMR SID_FIRST frame by its identification marker */ |
| 171 | static bool detect_afs_sid_update(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 172 | { |
| 173 | return detect_afs_id_marker(n_errors, n_bits_total, ubits, 36, 53, id_marker_0, 9); |
| 174 | } |
| 175 | |
| 176 | /* Detect an FR AMR SID_FIRST frame by its repeating coded inband data */ |
| 177 | static bool detect_afs_onset(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 178 | { |
| 179 | bool rc; |
| 180 | |
| 181 | rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_1_sid, 16); |
| 182 | if (rc) |
| 183 | return true; |
| 184 | |
| 185 | rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_2_sid, 16); |
| 186 | if (rc) |
| 187 | return true; |
| 188 | |
| 189 | rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_3_sid, 16); |
| 190 | if (rc) |
| 191 | return true; |
| 192 | |
| 193 | rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_4_sid, 16); |
| 194 | if (rc) |
| 195 | return true; |
| 196 | |
| 197 | return false; |
| 198 | } |
| 199 | |
| 200 | /* Detect an HR AMR SID UPDATE frame by its identification marker */ |
| 201 | static bool detect_ahs_sid_update(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 202 | { |
| 203 | return detect_ahs_id_marker(n_errors, n_bits_total, ubits, id_marker_1); |
| 204 | } |
| 205 | |
| 206 | /* Detect an HR AMR SID FIRST (part 1) frame by its identification marker */ |
| 207 | static bool detect_ahs_sid_first_p1(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 208 | { |
| 209 | return detect_ahs_id_marker(n_errors, n_bits_total, ubits, id_marker_0); |
| 210 | } |
| 211 | |
| 212 | /* Detect an HR AMR SID FIRST (part 2) frame by its repeating coded inband data */ |
| 213 | static bool detect_ahs_sid_first_p2(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 214 | { |
| 215 | bool rc; |
| 216 | |
| 217 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_1_sid, 16); |
| 218 | if (rc) |
| 219 | return true; |
| 220 | |
| 221 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_2_sid, 16); |
| 222 | if (rc) |
| 223 | return true; |
| 224 | |
| 225 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_3_sid, 16); |
| 226 | if (rc) |
| 227 | return true; |
| 228 | |
| 229 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_4_sid, 16); |
| 230 | if (rc) |
| 231 | return true; |
| 232 | |
| 233 | return false; |
| 234 | } |
| 235 | |
| 236 | /* Detect an HR AMR ONSET frame by its repeating coded inband data */ |
| 237 | static bool detect_ahs_onset(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 238 | { |
| 239 | bool rc; |
| 240 | |
| 241 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_1_sid, 16); |
| 242 | if (rc) |
| 243 | return true; |
| 244 | |
| 245 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_2_sid, 16); |
| 246 | if (rc) |
| 247 | return true; |
| 248 | |
| 249 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_3_sid, 16); |
| 250 | if (rc) |
| 251 | return true; |
| 252 | |
| 253 | rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_4_sid, 16); |
| 254 | if (rc) |
| 255 | return true; |
| 256 | |
| 257 | return false; |
| 258 | } |
| 259 | |
| 260 | /* Detect an HR AMR SID FIRST INHIBIT frame by its identification marker */ |
| 261 | static bool detect_ahs_sid_first_inh(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 262 | { |
| 263 | return detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 33, 212, id_marker_1, 9); |
| 264 | } |
| 265 | |
| 266 | /* Detect an HR AMR SID UPDATE INHIBIT frame by its identification marker */ |
| 267 | static bool detect_ahs_sid_update_inh(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 268 | { |
| 269 | return detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 33, 212, id_marker_0, 9); |
| 270 | } |
| 271 | |
| 272 | /*! Detect FR AMR DTX frame in unmapped, deinterleaved frame bits. |
| 273 | * \param[in] ubits input bits (456 bit). |
| 274 | * \param[out] n_errors number of errornous bits. |
| 275 | * \param[out] n_bits_total number of checked bits. |
| 276 | * \returns dtx frame type. */ |
| 277 | enum gsm0503_amr_dtx_frames gsm0503_detect_afs_dtx_frame(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 278 | { |
| 279 | if (detect_afs_sid_first(n_errors, n_bits_total, ubits)) |
| 280 | return AFS_SID_FIRST; |
| 281 | if (detect_afs_sid_update(n_errors, n_bits_total, ubits)) |
| 282 | return AFS_SID_UPDATE; |
| 283 | if (detect_afs_onset(n_errors, n_bits_total, ubits)) |
| 284 | return AFS_ONSET; |
| 285 | |
| 286 | *n_errors = 0; |
| 287 | *n_bits_total = 0; |
| 288 | return AMR_OTHER; |
| 289 | } |
| 290 | |
| 291 | /*! Detect HR AMR DTX frame in unmapped, deinterleaved frame bits. |
| 292 | * \param[in] ubits input bits (456 bit). |
| 293 | * \param[out] n_errors number of errornous bits. |
| 294 | * \param[out] n_bits_total number of checked bits. |
| 295 | * \returns dtx frame type, */ |
| 296 | enum gsm0503_amr_dtx_frames gsm0503_detect_ahs_dtx_frame(int *n_errors, int *n_bits_total, const ubit_t * ubits) |
| 297 | { |
| 298 | if (detect_ahs_sid_update(n_errors, n_bits_total, ubits)) |
| 299 | return AHS_SID_UPDATE; |
| 300 | if (detect_ahs_sid_first_inh(n_errors, n_bits_total, ubits)) |
| 301 | return AHS_SID_FIRST_INH; |
| 302 | if (detect_ahs_sid_update_inh(n_errors, n_bits_total, ubits)) |
| 303 | return AHS_SID_UPDATE_INH; |
| 304 | if (detect_ahs_sid_first_p1(n_errors, n_bits_total, ubits)) |
| 305 | return AHS_SID_FIRST_P1; |
| 306 | if (detect_ahs_sid_first_p2(n_errors, n_bits_total, ubits)) |
| 307 | return AHS_SID_FIRST_P2; |
| 308 | if (detect_ahs_onset(n_errors, n_bits_total, ubits)) |
| 309 | return AHS_ONSET; |
| 310 | |
| 311 | *n_errors = 0; |
| 312 | *n_bits_total = 0; |
| 313 | return AMR_OTHER; |
| 314 | } |