ptrkrysik | 8038b2e | 2014-12-15 23:10:48 +0100 | [diff] [blame] | 1 | /* |
| 2 | The Hacker's Choice - http://www.thc.org |
| 3 | Part of THC's GSM SCANNER PROJECT |
| 4 | */ |
| 5 | |
piotr | faacc72 | 2014-07-20 23:48:32 +0200 | [diff] [blame] | 6 | //#include "system.h" |
| 7 | #include <stdio.h> |
| 8 | #include <stdlib.h> |
| 9 | #include <unistd.h> |
| 10 | #include <string.h> |
| 11 | #include <ctype.h> |
| 12 | |
| 13 | //#include <exception> |
| 14 | //#include <stdexcept> |
| 15 | #include <math.h> |
| 16 | //#include "burst_types.h" |
| 17 | #include "cch.h" |
| 18 | #include "fire_crc.h" |
| 19 | |
| 20 | |
| 21 | /* |
| 22 | * GSM SACCH -- Slow Associated Control Channel |
| 23 | * |
| 24 | * These messages are encoded exactly the same as on the BCCH. |
| 25 | * (Broadcast Control Channel.) |
| 26 | * |
| 27 | * Input: 184 bits |
| 28 | * |
| 29 | * 1. Add parity and flushing bits. (Output 184 + 40 + 4 = 228 bit) |
| 30 | * 2. Convolutional encode. (Output 228 * 2 = 456 bit) |
| 31 | * 3. Interleave. (Output 456 bit) |
| 32 | * 4. Map on bursts. (4 x 156 bit bursts with each 2x57 bit content data) |
| 33 | */ |
| 34 | |
| 35 | |
| 36 | /* |
| 37 | * Parity (FIRE) for the GSM SACCH channel. |
| 38 | * |
| 39 | * g(x) = (x^23 + 1)(x^17 + x^3 + 1) |
| 40 | * = x^40 + x^26 + x^23 + x^17 + x^3 + 1 |
| 41 | */ |
| 42 | |
| 43 | static const unsigned char parity_polynomial[PARITY_SIZE + 1] = { |
| 44 | 1, 0, 0, 0, 0, 0, 0, 0, |
| 45 | 0, 0, 0, 0, 0, 0, 1, 0, |
| 46 | 0, 1, 0, 0, 0, 0, 0, 1, |
| 47 | 0, 0, 0, 0, 0, 0, 0, 0, |
| 48 | 0, 0, 0, 0, 0, 1, 0, 0, |
| 49 | 1 |
| 50 | }; |
| 51 | |
| 52 | // remainder after dividing data polynomial by g(x) |
| 53 | static const unsigned char parity_remainder[PARITY_SIZE] = { |
| 54 | 1, 1, 1, 1, 1, 1, 1, 1, |
| 55 | 1, 1, 1, 1, 1, 1, 1, 1, |
| 56 | 1, 1, 1, 1, 1, 1, 1, 1, |
| 57 | 1, 1, 1, 1, 1, 1, 1, 1, |
| 58 | 1, 1, 1, 1, 1, 1, 1, 1 |
| 59 | }; |
| 60 | |
| 61 | |
| 62 | /* |
| 63 | static void parity_encode(unsigned char *d, unsigned char *p) { |
| 64 | |
| 65 | int i; |
| 66 | unsigned char buf[DATA_BLOCK_SIZE + PARITY_SIZE], *q; |
| 67 | |
| 68 | memcpy(buf, d, DATA_BLOCK_SIZE); |
| 69 | memset(buf + DATA_BLOCK_SIZE, 0, PARITY_SIZE); |
| 70 | |
| 71 | for(q = buf; q < buf + DATA_BLOCK_SIZE; q++) |
| 72 | if(*q) |
| 73 | for(i = 0; i < PARITY_SIZE + 1; i++) |
| 74 | q[i] ^= parity_polynomial[i]; |
| 75 | for(i = 0; i < PARITY_SIZE; i++) |
| 76 | p[i] = !buf[DATA_BLOCK_SIZE + i]; |
| 77 | } |
| 78 | */ |
| 79 | |
| 80 | |
| 81 | int parity_check(unsigned char *d) { |
| 82 | |
| 83 | unsigned int i; |
| 84 | unsigned char buf[DATA_BLOCK_SIZE + PARITY_SIZE], *q; |
| 85 | |
| 86 | memcpy(buf, d, DATA_BLOCK_SIZE + PARITY_SIZE); |
| 87 | |
| 88 | for(q = buf; q < buf + DATA_BLOCK_SIZE; q++) |
| 89 | if(*q) |
| 90 | for(i = 0; i < PARITY_SIZE + 1; i++) |
| 91 | q[i] ^= parity_polynomial[i]; |
| 92 | return memcmp(buf + DATA_BLOCK_SIZE, parity_remainder, PARITY_SIZE); |
| 93 | } |
| 94 | |
| 95 | |
| 96 | /* |
| 97 | * Convolutional encoding and Viterbi decoding for the GSM SACCH channel. |
| 98 | */ |
| 99 | |
| 100 | /* |
| 101 | * Convolutional encoding: |
| 102 | * |
| 103 | * G_0 = 1 + x^3 + x^4 |
| 104 | * G_1 = 1 + x + x^3 + x^4 |
| 105 | * |
| 106 | * i.e., |
| 107 | * |
| 108 | * c_{2k} = u_k + u_{k - 3} + u_{k - 4} |
| 109 | * c_{2k + 1} = u_k + u_{k - 1} + u_{k - 3} + u_{k - 4} |
| 110 | */ |
| 111 | #define K 5 |
| 112 | #define MAX_ERROR (2 * CONV_INPUT_SIZE + 1) |
| 113 | |
| 114 | |
| 115 | /* |
| 116 | * Given the current state and input bit, what are the output bits? |
| 117 | * |
| 118 | * encode[current_state][input_bit] |
| 119 | */ |
| 120 | static const unsigned int encode[1 << (K - 1)][2] = { |
| 121 | {0, 3}, {3, 0}, {3, 0}, {0, 3}, |
| 122 | {0, 3}, {3, 0}, {3, 0}, {0, 3}, |
| 123 | {1, 2}, {2, 1}, {2, 1}, {1, 2}, |
| 124 | {1, 2}, {2, 1}, {2, 1}, {1, 2} |
| 125 | }; |
| 126 | |
| 127 | |
| 128 | /* |
| 129 | * Given the current state and input bit, what is the next state? |
| 130 | * |
| 131 | * next_state[current_state][input_bit] |
| 132 | */ |
| 133 | static const unsigned int next_state[1 << (K - 1)][2] = { |
| 134 | {0, 8}, {0, 8}, {1, 9}, {1, 9}, |
| 135 | {2, 10}, {2, 10}, {3, 11}, {3, 11}, |
| 136 | {4, 12}, {4, 12}, {5, 13}, {5, 13}, |
| 137 | {6, 14}, {6, 14}, {7, 15}, {7, 15} |
| 138 | }; |
| 139 | |
| 140 | |
| 141 | /* |
| 142 | * Given the previous state and the current state, what input bit caused |
| 143 | * the transition? If it is impossible to transition between the two |
| 144 | * states, the value is 2. |
| 145 | * |
| 146 | * prev_next_state[previous_state][current_state] |
| 147 | */ |
| 148 | static const unsigned int prev_next_state[1 << (K - 1)][1 << (K - 1)] = { |
| 149 | { 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2}, |
| 150 | { 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2}, |
| 151 | { 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2}, |
| 152 | { 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2}, |
| 153 | { 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2}, |
| 154 | { 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2}, |
| 155 | { 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2}, |
| 156 | { 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2}, |
| 157 | { 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2}, |
| 158 | { 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2}, |
| 159 | { 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2}, |
| 160 | { 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2}, |
| 161 | { 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2}, |
| 162 | { 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2}, |
| 163 | { 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1}, |
| 164 | { 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1} |
| 165 | }; |
| 166 | |
| 167 | |
| 168 | static inline unsigned int hamming_distance2(unsigned int w) { |
| 169 | |
| 170 | return (w & 1) + !!(w & 2); |
| 171 | } |
| 172 | |
| 173 | |
| 174 | /* |
| 175 | static void conv_encode(unsigned char *data, unsigned char *output) { |
| 176 | |
| 177 | unsigned int i, state = 0, o; |
| 178 | |
| 179 | // encode data |
| 180 | for(i = 0; i < CONV_INPUT_SIZE; i++) { |
| 181 | o = encode[state][data[i]]; |
| 182 | state = next_state[state][data[i]]; |
| 183 | *output++ = !!(o & 2); |
| 184 | *output++ = o & 1; |
| 185 | } |
| 186 | } |
| 187 | */ |
| 188 | |
| 189 | |
| 190 | int conv_decode(unsigned char *output, unsigned char *data) { |
| 191 | |
| 192 | int i, t; |
| 193 | unsigned int rdata, state, nstate, b, o, distance, accumulated_error, |
| 194 | min_state, min_error, cur_state; |
| 195 | |
| 196 | unsigned int ae[1 << (K - 1)]; // accumulated error |
| 197 | unsigned int nae[1 << (K - 1)]; // next accumulated error |
| 198 | unsigned int state_history[1 << (K - 1)][CONV_INPUT_SIZE + 1]; |
| 199 | |
| 200 | // initialize accumulated error, assume starting state is 0 |
| 201 | for(i = 0; i < (1 << (K - 1)); i++){ |
| 202 | ae[i] = nae[i] = MAX_ERROR; |
| 203 | } |
| 204 | |
| 205 | ae[0] = 0; |
| 206 | |
| 207 | // build trellis |
| 208 | for(t = 0; t < CONV_INPUT_SIZE; t++) { |
| 209 | |
| 210 | // get received data symbol |
| 211 | rdata = (data[2 * t] << 1) | data[2 * t + 1]; |
| 212 | |
| 213 | // for each state |
| 214 | for(state = 0; state < (1 << (K - 1)); state++) { |
| 215 | |
| 216 | // make sure this state is possible |
| 217 | if(ae[state] >= MAX_ERROR) |
| 218 | continue; |
| 219 | |
| 220 | // find all states we lead to |
| 221 | for(b = 0; b < 2; b++) { |
| 222 | |
| 223 | // get next state given input bit b |
| 224 | nstate = next_state[state][b]; |
| 225 | |
| 226 | // find output for this transition |
| 227 | o = encode[state][b]; |
| 228 | |
| 229 | // calculate distance from received data |
| 230 | distance = hamming_distance2(rdata ^ o); |
| 231 | |
| 232 | // choose surviving path |
| 233 | accumulated_error = ae[state] + distance; |
| 234 | if(accumulated_error < nae[nstate]) { |
| 235 | |
| 236 | // save error for surviving state |
| 237 | nae[nstate] = accumulated_error; |
| 238 | |
| 239 | // update state history |
| 240 | state_history[nstate][t + 1] = state; |
| 241 | } |
| 242 | } |
| 243 | } |
| 244 | |
| 245 | // get accumulated error ready for next time slice |
| 246 | for(i = 0; i < (1 << (K - 1)); i++) { |
| 247 | ae[i] = nae[i]; |
| 248 | nae[i] = MAX_ERROR; |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | // the final state is the state with the fewest errors |
| 253 | min_state = (unsigned int)-1; |
| 254 | min_error = MAX_ERROR; |
| 255 | for(i = 0; i < (1 << (K - 1)); i++) { |
| 256 | if(ae[i] < min_error) { |
| 257 | min_state = i; |
| 258 | min_error = ae[i]; |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | // trace the path |
| 263 | cur_state = min_state; |
| 264 | for(t = CONV_INPUT_SIZE; t >= 1; t--) { |
| 265 | min_state = cur_state; |
| 266 | cur_state = state_history[cur_state][t]; // get previous |
| 267 | output[t - 1] = prev_next_state[cur_state][min_state]; |
| 268 | } |
| 269 | |
| 270 | // return the number of errors detected (hard-decision) |
| 271 | return min_error; |
| 272 | } |
| 273 | |
| 274 | |
| 275 | /* |
| 276 | * GSM SACCH interleaving and burst mapping |
| 277 | * |
| 278 | * Interleaving: |
| 279 | * |
| 280 | * Given 456 coded input bits, form 4 blocks of 114 bits: |
| 281 | * |
| 282 | * i(B, j) = c(n, k) k = 0, ..., 455 |
| 283 | * n = 0, ..., N, N + 1, ... |
| 284 | * B = B_0 + 4n + (k mod 4) |
| 285 | * j = 2(49k mod 57) + ((k mod 8) div 4) |
| 286 | * |
| 287 | * Mapping on Burst: |
| 288 | * |
| 289 | * e(B, j) = i(B, j) |
| 290 | * e(B, 59 + j) = i(B, 57 + j) j = 0, ..., 56 |
| 291 | * e(B, 57) = h_l(B) |
| 292 | * e(B, 58) = h_n(B) |
| 293 | * |
| 294 | * Where h_l(B) and h_n(B) are bits in burst B indicating flags. |
| 295 | */ |
| 296 | |
| 297 | /* |
| 298 | static void interleave(unsigned char *data, unsigned char *iBLOCK) { |
| 299 | |
| 300 | int j, k, B; |
| 301 | |
| 302 | // for each bit in input data |
| 303 | for(k = 0; k < CONV_SIZE; k++) { |
| 304 | B = k % 4; |
| 305 | j = 2 * ((49 * k) % 57) + ((k % 8) / 4); |
| 306 | iBLOCK[B * iBLOCK_SIZE + j] = data[k]; |
| 307 | } |
| 308 | } |
| 309 | */ |
| 310 | |
| 311 | |
| 312 | #if 0 |
| 313 | static void decode_interleave(unsigned char *data, unsigned char *iBLOCK) { |
| 314 | |
| 315 | int j, k, B; |
| 316 | |
| 317 | for(k = 0; k < CONV_SIZE; k++) { |
| 318 | B = k % 4; |
| 319 | j = 2 * ((49 * k) % 57) + ((k % 8) / 4); |
| 320 | data[k] = iBLOCK[B * iBLOCK_SIZE + j]; |
| 321 | } |
| 322 | } |
| 323 | |
| 324 | #endif |
| 325 | |
| 326 | /* |
| 327 | static void burstmap(unsigned char *iBLOCK, unsigned char *eBLOCK, |
| 328 | unsigned char hl, unsigned char hn) { |
| 329 | |
| 330 | int j; |
| 331 | |
| 332 | for(j = 0; j < 57; j++) { |
| 333 | eBLOCK[j] = iBLOCK[j]; |
| 334 | eBLOCK[j + 59] = iBLOCK[j + 57]; |
| 335 | } |
| 336 | eBLOCK[57] = hl; |
| 337 | eBLOCK[58] = hn; |
| 338 | } |
| 339 | */ |
| 340 | |
| 341 | |
| 342 | static void decode_burstmap(unsigned char *iBLOCK, unsigned char *eBLOCK, |
| 343 | unsigned char *hl, unsigned char *hn) { |
| 344 | |
| 345 | int j; |
| 346 | |
| 347 | for(j = 0; j < 57; j++) { |
| 348 | iBLOCK[j] = eBLOCK[j]; |
| 349 | iBLOCK[j + 57] = eBLOCK[j + 59]; |
| 350 | } |
| 351 | *hl = eBLOCK[57]; |
| 352 | *hn = eBLOCK[58]; |
| 353 | } |
| 354 | |
| 355 | |
| 356 | /* |
| 357 | * Transmitted bits are sent least-significant first. |
| 358 | */ |
| 359 | static int compress_bits(unsigned char *dbuf, unsigned int dbuf_len, |
| 360 | unsigned char *sbuf, unsigned int sbuf_len) { |
| 361 | |
| 362 | unsigned int i, j, c, pos = 0; |
| 363 | |
| 364 | if(dbuf_len < ((sbuf_len + 7) >> 3)) |
| 365 | return -1; |
| 366 | |
| 367 | for(i = 0; i < sbuf_len; i += 8) { |
| 368 | for(j = 0, c = 0; (j < 8) && (i + j < sbuf_len); j++) |
| 369 | c |= (!!sbuf[i + j]) << j; |
| 370 | dbuf[pos++] = c & 0xff; |
| 371 | } |
| 372 | return pos; |
| 373 | } |
| 374 | |
| 375 | |
| 376 | #if 0 |
| 377 | int get_ns_l3_len(unsigned char *data, unsigned int datalen) { |
| 378 | |
| 379 | if((data[0] & 3) != 1) { |
| 380 | fprintf(stderr, "error: get_ns_l3_len: pseudo-length reserved " |
| 381 | "bits bad (%2.2x)\n", data[0] & 3); |
| 382 | return -1; |
| 383 | } |
| 384 | return (data[0] >> 2); |
| 385 | } |
| 386 | |
| 387 | #endif |
| 388 | |
| 389 | |
| 390 | /*static unsigned char *decode_sacch(GS_CTX *ctx, unsigned char *burst, unsigned int *datalen) {*/ |
| 391 | |
| 392 | /* int errors, len, data_size;*/ |
| 393 | /* unsigned char conv_data[CONV_SIZE], iBLOCK[BLOCKS][iBLOCK_SIZE],*/ |
| 394 | /* hl, hn, decoded_data[PARITY_OUTPUT_SIZE];*/ |
| 395 | /* FC_CTX fc_ctx;*/ |
| 396 | |
| 397 | /* data_size = sizeof ctx->msg;*/ |
| 398 | /* if(datalen)*/ |
| 399 | /* *datalen = 0;*/ |
| 400 | |
| 401 | /* // unmap the bursts*/ |
| 402 | /* decode_burstmap(iBLOCK[0], burst, &hl, &hn); // XXX ignore stealing bits*/ |
| 403 | /* decode_burstmap(iBLOCK[1], burst + 116, &hl, &hn);*/ |
| 404 | /* decode_burstmap(iBLOCK[2], burst + 116 * 2, &hl, &hn);*/ |
| 405 | /* decode_burstmap(iBLOCK[3], burst + 116 * 3, &hl, &hn);*/ |
| 406 | |
| 407 | /* // remove interleave*/ |
| 408 | /* interleave_decode(&ctx->interleave_ctx, conv_data, (unsigned char *)iBLOCK);*/ |
| 409 | /* //decode_interleave(conv_data, (unsigned char *)iBLOCK);*/ |
| 410 | |
| 411 | /* // Viterbi decode*/ |
| 412 | /* errors = conv_decode(decoded_data, conv_data);*/ |
| 413 | /* //DEBUGF("conv_decode: %d\n", errors);*/ |
| 414 | |
| 415 | /* // check parity*/ |
| 416 | /* // If parity check error detected try to fix it.*/ |
| 417 | /* if (parity_check(decoded_data))*/ |
| 418 | /* {*/ |
| 419 | /* unsigned char crc_result[224];*/ |
| 420 | /* if (FC_check_crc(&fc_ctx, decoded_data, crc_result) == 0)*/ |
| 421 | /* {*/ |
| 422 | /* errors = -1;*/ |
| 423 | /* //DEBUGF("error: sacch: parity error (%d fn=%d)\n",*/ |
| 424 | /* // errors, ctx->fn);*/ |
| 425 | /* return NULL;*/ |
| 426 | /* } else {*/ |
| 427 | /* //DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n",*/ |
| 428 | /* // errors, ctx->fn);*/ |
| 429 | /* memcpy(decoded_data, crc_result, sizeof crc_result);*/ |
| 430 | /* errors = 0;*/ |
| 431 | /* }*/ |
| 432 | /* }*/ |
| 433 | |
| 434 | /* if (errors)*/ |
| 435 | /* printf("WRN: errors=%d fn=%d\n", errors, ctx->fn);*/ |
| 436 | |
| 437 | /* if((len = compress_bits(ctx->msg, data_size, decoded_data,*/ |
| 438 | /* DATA_BLOCK_SIZE)) < 0) {*/ |
| 439 | /* fprintf(stderr, "error: compress_bits\n");*/ |
| 440 | /* return NULL;*/ |
| 441 | /* }*/ |
| 442 | /* if(len < data_size) {*/ |
| 443 | /* fprintf(stderr, "error: buf too small (%d < %d)\n",*/ |
| 444 | /* sizeof(ctx->msg), len);*/ |
| 445 | /* return NULL;*/ |
| 446 | /* }*/ |
| 447 | |
| 448 | /* if(datalen)*/ |
| 449 | /* *datalen = (unsigned int)len;*/ |
| 450 | /* return ctx->msg;*/ |
| 451 | /*}*/ |
| 452 | |
| 453 | |
| 454 | /* |
| 455 | * decode_cch |
| 456 | * |
| 457 | * Decode a "common" control channel. Most control channels use |
| 458 | * the same burst, interleave, Viterbi and parity configuration. |
| 459 | * The documentation for the control channels defines SACCH first |
| 460 | * and then just keeps referring to that. |
| 461 | * |
| 462 | * The current (investigated) list is as follows: |
| 463 | * |
| 464 | * BCCH Norm |
| 465 | * BCCH Ext |
| 466 | * PCH |
| 467 | * AGCH |
| 468 | * CBCH (SDCCH/4) |
| 469 | * CBCH (SDCCH/8) |
| 470 | * SDCCH/4 |
| 471 | * SACCH/C4 |
| 472 | * SDCCH/8 |
| 473 | * SACCH/C8 |
| 474 | * |
| 475 | * We provide two functions, one for where all four bursts are |
| 476 | * contiguous, and one where they aren't. |
| 477 | */ |
| 478 | /*unsigned char *decode_cch(GS_CTX *ctx, unsigned char *burst, unsigned int *datalen) {*/ |
| 479 | |
| 480 | /* return decode_sacch(ctx, burst, datalen);*/ |
| 481 | /*}*/ |
| 482 | |
| 483 | |
| 484 | #if 0 |
| 485 | unsigned char *decode_cch(GS_CTX *ctx, unsigned char *e, unsigned int *datalen) { |
| 486 | |
| 487 | return decode_sacch(ctx, e, e + eBLOCK_SIZE, e + 2 * eBLOCK_SIZE, |
| 488 | e + 3 * eBLOCK_SIZE, datalen); |
| 489 | } |
| 490 | #endif |
| 491 | |
| 492 | /*unsigned char *decode_facch(GS_CTX *ctx, unsigned char *burst, unsigned int *datalen, int offset) {*/ |
| 493 | |
| 494 | /* int errors, len, data_size;*/ |
| 495 | /* unsigned char conv_data[CONV_SIZE], iBLOCK[BLOCKS * 2][iBLOCK_SIZE],*/ |
| 496 | /* hl, hn, decoded_data[PARITY_OUTPUT_SIZE];*/ |
| 497 | /* FC_CTX fc_ctx;*/ |
| 498 | |
| 499 | /* data_size = sizeof ctx->msg;*/ |
| 500 | /* if(datalen)*/ |
| 501 | /* *datalen = 0;*/ |
| 502 | |
| 503 | /* // unmap the bursts*/ |
| 504 | /* decode_burstmap(iBLOCK[0], burst, &hl, &hn); // XXX ignore stealing bits*/ |
| 505 | /* decode_burstmap(iBLOCK[1], burst + 116, &hl, &hn);*/ |
| 506 | /* decode_burstmap(iBLOCK[2], burst + 116 * 2, &hl, &hn);*/ |
| 507 | /* decode_burstmap(iBLOCK[3], burst + 116 * 3, &hl, &hn);*/ |
| 508 | /* decode_burstmap(iBLOCK[4], burst + 116 * 4, &hl, &hn);*/ |
| 509 | /* decode_burstmap(iBLOCK[5], burst + 116 * 5, &hl, &hn);*/ |
| 510 | /* decode_burstmap(iBLOCK[6], burst + 116 * 6, &hl, &hn);*/ |
| 511 | /* decode_burstmap(iBLOCK[7], burst + 116 * 7, &hl, &hn);*/ |
| 512 | |
| 513 | /* // remove interleave*/ |
| 514 | /* if (offset == 0)*/ |
| 515 | /* interleave_decode(&ctx->interleave_facch_f1_ctx, conv_data, (unsigned char *)iBLOCK);*/ |
| 516 | /* else*/ |
| 517 | /* interleave_decode(&ctx->interleave_facch_f2_ctx, conv_data, (unsigned char *)iBLOCK);*/ |
| 518 | /* //decode_interleave(conv_data, (unsigned char *)iBLOCK);*/ |
| 519 | |
| 520 | /* // Viterbi decode*/ |
| 521 | /* errors = conv_decode(decoded_data, conv_data);*/ |
| 522 | /* //DEBUGF("conv_decode: %d\n", errors);*/ |
| 523 | |
| 524 | /* // check parity*/ |
| 525 | /* // If parity check error detected try to fix it.*/ |
| 526 | /* if (parity_check(decoded_data)) {*/ |
| 527 | /* FC_init(&fc_ctx, 40, 184);*/ |
| 528 | /* unsigned char crc_result[224];*/ |
| 529 | /* if (FC_check_crc(&fc_ctx, decoded_data, crc_result) == 0)*/ |
| 530 | /* {*/ |
| 531 | /* //DEBUGF("error: sacch: parity error (errors=%d fn=%d)\n", errors, ctx->fn);*/ |
| 532 | /* errors = -1;*/ |
| 533 | /* return NULL;*/ |
| 534 | /* } else {*/ |
| 535 | /* //DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n", errors, ctx->fn);*/ |
| 536 | /* memcpy(decoded_data, crc_result, sizeof crc_result);*/ |
| 537 | /* errors = 0;*/ |
| 538 | /* }*/ |
| 539 | /* }*/ |
| 540 | |
| 541 | /* if (errors)*/ |
| 542 | /* fprintf(stderr, "WRN: errors=%d fn=%d\n", errors, ctx->fn);*/ |
| 543 | |
| 544 | /* if ((len = compress_bits(ctx->msg, data_size, decoded_data,*/ |
| 545 | /* DATA_BLOCK_SIZE)) < 0) {*/ |
| 546 | /* fprintf(stderr, "error: compress_bits\n");*/ |
| 547 | /* return NULL;*/ |
| 548 | /* }*/ |
| 549 | /* if (len < data_size) {*/ |
| 550 | /* fprintf(stderr, "error: buf too small (%d < %d)\n",*/ |
| 551 | /* sizeof(ctx->msg), len);*/ |
| 552 | /* return NULL;*/ |
| 553 | /* }*/ |
| 554 | |
| 555 | /* if (datalen)*/ |
| 556 | /* *datalen = (unsigned int)len;*/ |
| 557 | /* return ctx->msg;*/ |
| 558 | /*}*/ |