Harald Welte | c4cfb80 | 2022-11-29 23:16:52 +0100 | [diff] [blame] | 1 | /************************************************************************* |
| 2 | * GSM CSD modified V.110 frame decoding/encoding (ubits <-> struct with D/S/X/E bits) |
| 3 | *************************************************************************/ |
| 4 | |
| 5 | /* (C) 2022 by Harald Welte <laforge@osmocom.org> |
| 6 | * |
| 7 | * SPDX-License-Identifier: GPL-2.0+ |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License as published by |
| 11 | * the Free Software Foundation; either version 2 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This program is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | * GNU General Public License for more details. |
| 18 | */ |
| 19 | |
| 20 | #include <errno.h> |
| 21 | #include <osmocom/core/bits.h> |
| 22 | #include <osmocom/isdn/v110.h> |
| 23 | |
| 24 | /*! Decode a 60-bit GSM 12kbit/s CSD frame present as 60 ubits into a struct osmo_v110_decoded_frame. |
| 25 | * \param[out] caller-allocated output data structure, filled by this function |
| 26 | * \param[in] ra_bits One V.110 frame as 60 unpacked bits. */ |
| 27 | int osmo_csd_12k_6k_decode_frame(struct osmo_v110_decoded_frame *fr, const ubit_t *ra_bits, size_t n_bits) |
| 28 | { |
| 29 | /* 3GPP TS 44.021 Section 8.1.2 / 8.1.3 |
| 30 | D1 D2 D3 D4 D5 D6 S1 |
| 31 | D7 D8 D9 D10 D11 D12 X |
| 32 | D13 D14 D15 D16 D17 D18 S3 |
| 33 | D19 D20 D21 D22 D23 D24 S4 |
| 34 | E4 E5 E6 E7 D25 D26 D27 |
| 35 | D28 D29 D30 S6 D31 D32 D33 |
| 36 | D34 D35 D36 X D37 D38 D39 |
| 37 | D40 D41 D42 S8 D43 D44 D45 |
| 38 | D46 D47 D48 S9 */ |
| 39 | |
| 40 | if (n_bits < 60) |
| 41 | return -EINVAL; |
| 42 | |
| 43 | /* X1 .. X2 */ |
| 44 | fr->x_bits[0] = ra_bits[1 * 7 + 6]; |
| 45 | fr->x_bits[1] = ra_bits[6 * 7 + 3]; |
| 46 | |
| 47 | /* S1, S3, S4, S6, S8, S9 */ |
| 48 | fr->s_bits[0] = ra_bits[0 * 7 + 6]; |
| 49 | fr->s_bits[2] = ra_bits[2 * 7 + 6]; |
| 50 | fr->s_bits[3] = ra_bits[3 * 7 + 6]; |
| 51 | fr->s_bits[5] = ra_bits[5 * 7 + 3]; |
| 52 | fr->s_bits[7] = ra_bits[7 * 7 + 3]; |
| 53 | fr->s_bits[8] = ra_bits[8 * 7 + 3]; |
| 54 | |
| 55 | /* E1 .. E3 must be set by out-of-band knowledge! */ |
| 56 | |
| 57 | /* E4 .. E7 */ |
| 58 | memcpy(fr->e_bits+3, ra_bits + 4 * 7 + 0, 4); |
| 59 | |
| 60 | /* D-bits */ |
| 61 | memcpy(fr->d_bits + 0 * 6 + 0, ra_bits + 0 * 7 + 0, 6); |
| 62 | memcpy(fr->d_bits + 1 * 6 + 0, ra_bits + 1 * 7 + 0, 6); |
| 63 | memcpy(fr->d_bits + 2 * 6 + 0, ra_bits + 2 * 7 + 0, 6); |
| 64 | memcpy(fr->d_bits + 3 * 6 + 0, ra_bits + 3 * 7 + 0, 6); |
| 65 | memcpy(fr->d_bits + 4 * 6 + 0, ra_bits + 4 * 7 + 4, 3); |
| 66 | memcpy(fr->d_bits + 4 * 6 + 3, ra_bits + 5 * 7 + 0, 3); |
| 67 | memcpy(fr->d_bits + 5 * 6 + 0, ra_bits + 5 * 7 + 4, 3); |
| 68 | memcpy(fr->d_bits + 5 * 6 + 3, ra_bits + 6 * 7 + 0, 3); |
| 69 | memcpy(fr->d_bits + 6 * 6 + 0, ra_bits + 6 * 7 + 4, 3); |
| 70 | memcpy(fr->d_bits + 6 * 6 + 3, ra_bits + 7 * 7 + 0, 3); |
| 71 | memcpy(fr->d_bits + 7 * 6 + 0, ra_bits + 7 * 7 + 4, 3); |
| 72 | memcpy(fr->d_bits + 7 * 6 + 3, ra_bits + 8 * 7 + 0, 3); |
| 73 | |
| 74 | return 0; |
| 75 | } |
| 76 | |
| 77 | int osmo_csd_12k_6k_encode_frame(ubit_t *ra_bits, size_t ra_bits_size, const struct osmo_v110_decoded_frame *fr) |
| 78 | { |
| 79 | if (ra_bits_size < 60) |
| 80 | return -EINVAL; |
| 81 | |
| 82 | /* X1 .. X2 */ |
| 83 | ra_bits[1 * 7 + 6] = fr->x_bits[0]; |
| 84 | ra_bits[6 * 7 + 3] = fr->x_bits[1]; |
| 85 | |
| 86 | /* S1, S3, S4, S6, S8, S9 */ |
| 87 | ra_bits[0 * 7 + 6] = fr->s_bits[0]; |
| 88 | ra_bits[2 * 7 + 6] = fr->s_bits[2]; |
| 89 | ra_bits[3 * 7 + 6] = fr->s_bits[3]; |
| 90 | ra_bits[5 * 7 + 3] = fr->s_bits[5]; |
| 91 | ra_bits[7 * 7 + 3] = fr->s_bits[7]; |
| 92 | ra_bits[8 * 7 + 3] = fr->s_bits[8]; |
| 93 | |
| 94 | /* E1 .. E3 are dropped */ |
| 95 | |
| 96 | /* E4 .. E7 */ |
| 97 | memcpy(ra_bits + 4 * 7 + 0, fr->e_bits+3, 4); |
| 98 | |
| 99 | /* D-bits */ |
| 100 | memcpy(ra_bits + 0 * 7 + 0, fr->d_bits + 0 * 6 + 0, 6); |
| 101 | memcpy(ra_bits + 1 * 7 + 0, fr->d_bits + 1 * 6 + 0, 6); |
| 102 | memcpy(ra_bits + 2 * 7 + 0, fr->d_bits + 2 * 6 + 0, 6); |
| 103 | memcpy(ra_bits + 3 * 7 + 0, fr->d_bits + 3 * 6 + 0, 6); |
| 104 | memcpy(ra_bits + 4 * 7 + 4, fr->d_bits + 4 * 6 + 0, 3); |
| 105 | memcpy(ra_bits + 5 * 7 + 0, fr->d_bits + 4 * 6 + 3, 3); |
| 106 | memcpy(ra_bits + 5 * 7 + 4, fr->d_bits + 5 * 6 + 0, 3); |
| 107 | memcpy(ra_bits + 6 * 7 + 0, fr->d_bits + 5 * 6 + 3, 3); |
| 108 | memcpy(ra_bits + 6 * 7 + 4, fr->d_bits + 6 * 6 + 0, 3); |
| 109 | memcpy(ra_bits + 7 * 7 + 0, fr->d_bits + 6 * 6 + 3, 3); |
| 110 | memcpy(ra_bits + 7 * 7 + 4, fr->d_bits + 7 * 6 + 0, 3); |
| 111 | memcpy(ra_bits + 8 * 7 + 0, fr->d_bits + 7 * 6 + 3, 3); |
| 112 | |
| 113 | return 60; |
| 114 | } |
| 115 | |
| 116 | /*! Decode a 36-bit GSM 3k6kbit/s CSD frame present as 36 ubits into a struct osmo_v110_decoded_frame. |
| 117 | * \param[out] caller-allocated output data structure, filled by this function |
| 118 | * \param[in] ra_bits One V.110 frame as 36 unpacked bits. */ |
| 119 | int osmo_csd_3k6_decode_frame(struct osmo_v110_decoded_frame *fr, const ubit_t *ra_bits, size_t n_bits) |
| 120 | { |
| 121 | |
| 122 | /* 3GPP TS 44.021 Section 8.1.4 |
| 123 | D1 D2 D3 S1 D4 D5 D6 X |
| 124 | D7 D8 D9 S3 D10 D11 D12 S4 |
| 125 | E4 E5 E6 E7 D13 D14 D15 S6 |
| 126 | D16 D17 D18 X D19 D20 D21 S8 |
| 127 | D22 D23 D24 S9 |
| 128 | */ |
| 129 | |
| 130 | if (n_bits < 36) |
| 131 | return -EINVAL; |
| 132 | |
| 133 | /* X1 .. X2 */ |
| 134 | fr->x_bits[0] = ra_bits[0 * 8 + 7]; |
| 135 | fr->x_bits[1] = ra_bits[3 * 8 + 3]; |
| 136 | |
| 137 | /* S1, S3, S4, S6, S8, S9 */ |
| 138 | fr->s_bits[0] = ra_bits[0 * 8 + 3]; |
| 139 | fr->s_bits[2] = ra_bits[1 * 8 + 3]; |
| 140 | fr->s_bits[3] = ra_bits[1 * 8 + 7]; |
| 141 | fr->s_bits[5] = ra_bits[2 * 8 + 7]; |
| 142 | fr->s_bits[7] = ra_bits[3 * 8 + 7]; |
| 143 | fr->s_bits[8] = ra_bits[4 * 8 + 3]; |
| 144 | |
| 145 | /* E1 .. E3 must be set by out-of-band knowledge! */ |
| 146 | |
| 147 | /* E4 .. E7 */ |
| 148 | memcpy(fr->e_bits+3, ra_bits + 2 * 8 + 0, 4); |
| 149 | |
| 150 | /* D-bits */ |
| 151 | unsigned int d_idx = 0; |
| 152 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 0]; /* D1 */ |
| 153 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 0]; /* D1 */ |
| 154 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 1]; /* D2 */ |
| 155 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 1]; /* D2 */ |
| 156 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 2]; /* D3 */ |
| 157 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 2]; /* D3 */ |
| 158 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 4]; /* D4 */ |
| 159 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 4]; /* D4 */ |
| 160 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 5]; /* D5 */ |
| 161 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 5]; /* D5 */ |
| 162 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 6]; /* D6 */ |
| 163 | fr->d_bits[d_idx++] = ra_bits[0 * 8 + 6]; /* D6 */ |
| 164 | |
| 165 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 0]; /* D7 */ |
| 166 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 0]; /* D7 */ |
| 167 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 1]; /* D8 */ |
| 168 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 1]; /* D8 */ |
| 169 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 2]; /* D9 */ |
| 170 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 2]; /* D9 */ |
| 171 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 4]; /* D10 */ |
| 172 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 4]; /* D10 */ |
| 173 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 5]; /* D11 */ |
| 174 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 5]; /* D11 */ |
| 175 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 6]; /* D12 */ |
| 176 | fr->d_bits[d_idx++] = ra_bits[1 * 8 + 6]; /* D12 */ |
| 177 | |
| 178 | fr->d_bits[d_idx++] = ra_bits[2 * 8 + 4]; /* D13 */ |
| 179 | fr->d_bits[d_idx++] = ra_bits[2 * 8 + 4]; /* D13 */ |
| 180 | fr->d_bits[d_idx++] = ra_bits[2 * 8 + 5]; /* D14 */ |
| 181 | fr->d_bits[d_idx++] = ra_bits[2 * 8 + 5]; /* D14 */ |
| 182 | fr->d_bits[d_idx++] = ra_bits[2 * 8 + 6]; /* D15 */ |
| 183 | fr->d_bits[d_idx++] = ra_bits[2 * 8 + 6]; /* D15 */ |
| 184 | |
| 185 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 0]; /* D16 */ |
| 186 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 0]; /* D16 */ |
| 187 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 1]; /* D17 */ |
| 188 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 1]; /* D17 */ |
| 189 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 2]; /* D18 */ |
| 190 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 2]; /* D18 */ |
| 191 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 4]; /* D19 */ |
| 192 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 4]; /* D19 */ |
| 193 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 5]; /* D20 */ |
| 194 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 5]; /* D20 */ |
| 195 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 6]; /* D21 */ |
| 196 | fr->d_bits[d_idx++] = ra_bits[3 * 8 + 6]; /* D21 */ |
| 197 | |
| 198 | fr->d_bits[d_idx++] = ra_bits[4 * 8 + 0]; /* D22 */ |
| 199 | fr->d_bits[d_idx++] = ra_bits[4 * 8 + 0]; /* D22 */ |
| 200 | fr->d_bits[d_idx++] = ra_bits[4 * 8 + 1]; /* D23 */ |
| 201 | fr->d_bits[d_idx++] = ra_bits[4 * 8 + 1]; /* D23 */ |
| 202 | fr->d_bits[d_idx++] = ra_bits[4 * 8 + 2]; /* D24 */ |
| 203 | fr->d_bits[d_idx++] = ra_bits[4 * 8 + 2]; /* D24 */ |
| 204 | |
| 205 | OSMO_ASSERT(d_idx == 48); |
| 206 | |
| 207 | return 0; |
| 208 | } |
| 209 | |
| 210 | int osmo_csd_3k6_encode_frame(ubit_t *ra_bits, size_t ra_bits_size, const struct osmo_v110_decoded_frame *fr) |
| 211 | { |
| 212 | if (ra_bits_size < 36) |
| 213 | return -EINVAL; |
| 214 | |
| 215 | /* X1 .. X2 */ |
| 216 | ra_bits[0 * 8 + 7] = fr->x_bits[0]; |
| 217 | ra_bits[3 * 8 + 3] = fr->x_bits[1]; |
| 218 | |
| 219 | /* S1, S3, S4, S6, S8, S9 */ |
| 220 | ra_bits[0 * 8 + 3] = fr->s_bits[0]; |
| 221 | ra_bits[1 * 8 + 3] = fr->s_bits[2]; |
| 222 | ra_bits[1 * 8 + 7] = fr->s_bits[3]; |
| 223 | ra_bits[2 * 8 + 7] = fr->s_bits[5]; |
| 224 | ra_bits[3 * 8 + 7] = fr->s_bits[7]; |
| 225 | ra_bits[4 * 8 + 3] = fr->s_bits[8]; |
| 226 | |
| 227 | /* E1 .. E3 are ignored */ |
| 228 | |
| 229 | /* E4 .. E7 */ |
| 230 | memcpy(ra_bits + 2 * 8 + 0, fr->e_bits+3, 4); |
| 231 | |
| 232 | /* D-bits */ |
| 233 | unsigned int d_idx = 0; |
| 234 | ra_bits[0 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2; |
| 235 | ra_bits[0 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2; |
| 236 | ra_bits[0 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2; |
| 237 | ra_bits[0 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2; |
| 238 | ra_bits[0 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2; |
| 239 | ra_bits[0 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2; |
| 240 | |
| 241 | ra_bits[1 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2; |
| 242 | ra_bits[1 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2; |
| 243 | ra_bits[1 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2; |
| 244 | ra_bits[1 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2; |
| 245 | ra_bits[1 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2; |
| 246 | ra_bits[1 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2; |
| 247 | |
| 248 | ra_bits[2 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2; |
| 249 | ra_bits[2 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2; |
| 250 | ra_bits[2 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2; |
| 251 | |
| 252 | ra_bits[3 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2; |
| 253 | ra_bits[3 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2; |
| 254 | ra_bits[3 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2; |
| 255 | ra_bits[3 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2; |
| 256 | ra_bits[3 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2; |
| 257 | ra_bits[3 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2; |
| 258 | |
| 259 | ra_bits[4 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2; |
| 260 | ra_bits[4 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2; |
| 261 | ra_bits[4 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2; |
| 262 | |
| 263 | OSMO_ASSERT(d_idx == 48); |
| 264 | |
| 265 | return 36; |
| 266 | } |
| 267 | |
| 268 | /*! Print a encoded "CSD modififed V.110" frame in the same table-like structure as the spec. |
| 269 | * \param outf output FILE stream to which to dump |
| 270 | * \param[in] fr unpacked bits to dump |
| 271 | * \param[in] in_len length of unpacked bits available at fr. */ |
| 272 | void osmo_csd_ubit_dump(FILE *outf, const ubit_t *fr, size_t in_len) |
| 273 | { |
| 274 | switch (in_len) { |
| 275 | case 60: |
| 276 | for (unsigned int septet = 0; septet < 9; septet++) { |
| 277 | if (septet < 8) { |
| 278 | fprintf(outf, "%d\t%d\t%d\t%d\t%d\t%d\t%d\n", fr[septet * 7 + 0], |
| 279 | fr[septet * 7 + 1], fr[septet * 7 + 2], fr[septet * 7 + 3], |
| 280 | fr[septet * 7 + 4], fr[septet * 7 + 5], fr[septet*7 + 6]); |
| 281 | } else { |
| 282 | fprintf(outf, "%d\t%d\t%d\t%d\n", fr[septet * 7 + 0], |
| 283 | fr[septet * 7 + 1], fr[septet * 7 + 2], fr[septet * 7 + 3]); |
| 284 | } |
| 285 | } |
| 286 | break; |
| 287 | case 36: |
| 288 | for (unsigned int octet = 0; octet < 5; octet++) { |
| 289 | if (octet < 4) { |
| 290 | fprintf(outf, "%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\n", |
| 291 | fr[octet * 8 + 0], fr[octet * 8 + 1], fr[octet * 8 + 2], |
| 292 | fr[octet * 8 + 3], fr[octet * 8 + 4], fr[octet * 8 + 5], |
| 293 | fr[octet * 8 + 6], fr[octet * 8 + 7]); |
| 294 | } else { |
| 295 | fprintf(outf, "%d\t%d\t%d\t%d\n", fr[octet * 8 + 0], |
| 296 | fr[octet * 8 + 1], fr[octet * 8 + 2], fr[octet * 8 + 3]); |
| 297 | } |
| 298 | } |
| 299 | break; |
| 300 | default: |
| 301 | fprintf(outf, "invalid input data length: %zu\n", in_len); |
| 302 | } |
| 303 | } |