/* GMR-1 Demo RX application */ /* (C) 2011-2019 by Sylvain Munaut * All Rights Reserved * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as published by * the Free Software Foundation; either version 3 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 Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see . */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define START_DISCARD 8000 static struct gsmtap_inst *g_gti; static const struct gmr1_fcch_burst *fcch_type = &gmr1_fcch_burst; struct tch3_state { /* Status */ int active; /* Channel params */ int tn; int p; int ciph; /* Energy */ float energy_dkab; float energy_burst; int weak_cnt; /* FACCH state */ sbit_t ebits[104*4]; uint32_t bi_fn[4]; int sync_id; int burst_cnt; }; struct tch9_state { /* Status */ int active; /* Channel params */ int tn; /* Interleaver */ struct gmr1_interleaver il; }; struct chan_desc { /* Sample source */ struct cfile *bcch; struct cfile *tch; struct cfile *tch_csd; int sps; /* SDR alignement */ int align; float freq_err; /* TDMA alignement */ int fn; int sa_sirfn_delay; int sa_bcch_stn; /* TCH */ struct tch3_state tch3_state; struct tch9_state tch9_state; /* A5 */ uint8_t kc[8]; }; /* Helpers ---------------------------------------------------------------- */ static inline float to_ms(struct chan_desc *cd, int s) { return (1000.0f * (float)s) / (cd->sps * GMR1_SYM_RATE); } static inline float to_hz(float f_rps) { return (GMR1_SYM_RATE * f_rps) / (2.0f * M_PIf); } static inline float to_db(float v) { return 10.0f * log10f(v); } static int win_map(struct osmo_cxvec *win, struct cfile *cf, int begin, int len) { if ((begin + len) > cf->len) return -1; osmo_cxvec_init_from_data(win, &cf->data[begin], len); return 0; } static int burst_map(struct osmo_cxvec *burst, struct chan_desc *cd, struct gmr1_pi4cxpsk_burst *burst_type, int tn, int win, int tch) { int begin, len; int etoa; struct cfile *df = tch == 2 ? cd->tch_csd : (tch ? cd->tch : cd->bcch); if (!df) return -EINVAL; etoa = win >> 1; begin = cd->align + (cd->sps * tn * 39) - etoa; len = (burst_type->len * cd->sps) + win; if ((begin + len) > cd->bcch->len) return -EIO; osmo_cxvec_init_from_data(burst, &df->data[begin], len); return etoa; } static float burst_energy(struct osmo_cxvec *burst) { int i; float e = 0.0f; int b = (burst->len >> 5); /* exclude the borders */ for (i=b; ilen-b; i++) e += osmo_normsqf(burst->data[i]); e /= burst->len; return e; } /* wrapper around gsmtap_sendmsg() to avoid memory leaks */ static void _gsmtap_sendmsg(struct gsmtap_inst *gti, struct msgb *msg) { if (gsmtap_sendmsg(gti, msg) < 0) msgb_free(msg); } /* Message parsing -------------------------------------------------------- */ static int bcch_tdma_align(struct chan_desc *cd, uint8_t *l2) { int sa_sirfn_delay, sa_bcch_stn; int superframe_num, multiframe_num, mffn_high_bit; int fn; /* Check if it's a SI1 */ if ((l2[0] & 0xf8) != 0x08) return 0; /* Check if it contains a Seg 2A bis */ if ((l2[9] & 0xfc) != 0x80) return 0; /* Retrieve SA_SIRFN_DELAY, SA_BCCH_STN, * Superframe number, Multiframe number, MFFN high bit */ sa_sirfn_delay = (l2[10] >> 3) & 0x0f; sa_bcch_stn = ((l2[10] << 2) & 0x1c) | (l2[11] >> 6); superframe_num = ((l2[11] & 0x3f) << 7) | (l2[12] >> 1); multiframe_num = ((l2[12] & 0x01) << 1) | (l2[13] >> 7); mffn_high_bit = ((l2[13] & 0x40) >> 6); /* Compute frame number */ fn = (superframe_num << 6) | (multiframe_num << 4) | (mffn_high_bit << 3) | ((2 + sa_sirfn_delay) & 7); /* Fix SDR alignement */ cd->align += (cd->sa_bcch_stn - sa_bcch_stn) * 39 * cd->sps; /* Align TDMA */ cd->fn = fn; cd->sa_sirfn_delay = sa_sirfn_delay; cd->sa_bcch_stn = sa_bcch_stn; return 0; } static inline int ccch_is_imm_ass(const uint8_t *l2) { return (l2[1] == 0x06) && (l2[2] == 0x3f); } static void ccch_imm_ass_parse(const uint8_t *l2, int *rx_tn, int *p) { *p = (l2[8] & 0xfc) >> 2; *rx_tn = ((l2[8] & 0x03) << 3) | (l2[9] >> 5); } static inline int facch3_is_ass_cmd_1(const uint8_t *l2) { return (l2[3] == 0x06) && (l2[4] == 0x2e); } static void facch3_ass_cmd_1_parse(const uint8_t *l2, int *rx_tn) { *rx_tn = ((l2[5] & 0x03) << 3) | (l2[6] >> 5); } /* TCH9 Procesing --------------------------------------------------------- */ static void rx_tch9_init(struct chan_desc *cd, const uint8_t *ass_cmd) { /* Activate */ cd->tch9_state.active = 1; /* Extract TN */ facch3_ass_cmd_1_parse(ass_cmd, &cd->tch9_state.tn); /* Init interleaver */ gmr1_interleaver_init(&cd->tch9_state.il, 3, 648); } static int rx_tch9(struct chan_desc *cd) { struct osmo_cxvec _burst, *burst = &_burst; int e_toa, rv, sync_id, crc, conv; sbit_t ebits[662], bits_sacch[10], bits_status[4]; ubit_t ciph[658]; float toa; /* Is TCH active at all ? */ if (!cd->tch9_state.active) return 0; /* Map potential burst */ e_toa = burst_map(burst, cd, &gmr1_nt9_burst, cd->tch9_state.tn, cd->sps + (cd->sps/2), 2); if (e_toa < 0) return e_toa; /* Demodulate burst */ rv = gmr1_pi4cxpsk_demod( &gmr1_nt9_burst, burst, cd->sps, -cd->freq_err, ebits, &sync_id, &toa, NULL ); fprintf(stderr, "[.] %s\n", sync_id ? "TCH9" : "FACCH9"); fprintf(stderr, "toa=%.1f, sync_id=%d\n", toa, sync_id); /* Process depending on type */ if (!sync_id) { /* FACCH9 */ uint8_t l2[38]; /* Generate cipher stream */ gmr1_a5(1, cd->kc, cd->fn, 658, ciph, NULL); /* Decode */ crc = gmr1_facch9_decode(l2, bits_sacch, bits_status, ebits, ciph, &conv); fprintf(stderr, "crc=%d, conv=%d\n", crc, conv); /* Send to GSMTap if correct */ if (!crc) _gsmtap_sendmsg(g_gti, gmr1_gsmtap_makemsg( GSMTAP_GMR1_TCH9 | GSMTAP_GMR1_FACCH, cd->fn, cd->tch9_state.tn, l2, 38)); } else { /* TCH9 */ uint8_t l2[60]; int i, s = 0; /* Generate cipher stream */ gmr1_a5(1, cd->kc, cd->fn, 658, ciph, NULL); for (i=0; i<662; i++) s += ebits[i] < 0 ? -ebits[i] : ebits[i]; s /= 662; /* Decode */ gmr1_tch9_decode(l2, bits_sacch, bits_status, ebits, GMR1_TCH9_9k6, ciph, &cd->tch9_state.il, &conv); fprintf(stderr, "fn=%d, conv9=%d, avg=%d\n", cd->fn, conv, s); /* Forward to GSMTap (no CRC to validate :( ) */ _gsmtap_sendmsg(g_gti, gmr1_gsmtap_makemsg( GSMTAP_GMR1_TCH9, cd->fn, cd->tch9_state.tn, l2, 60)); /* Save to file */ { static FILE *f = NULL; if (!f) f = fopen("/tmp/csd.data", "wb"); fwrite(l2, 60, 1, f); } } /* Done */ return rv; } /* TCH3 Procesing --------------------------------------------------------- */ static void rx_tch3_init(struct chan_desc *cd, const uint8_t *imm_ass, float ref_energy) { /* Activate */ cd->tch3_state.active = 1; /* Extract TN & DKAB position */ ccch_imm_ass_parse(imm_ass, &cd->tch3_state.tn, &cd->tch3_state.p); /* Estimate energy threshold */ cd->tch3_state.energy_burst = ref_energy * 0.75f; cd->tch3_state.energy_dkab = cd->tch3_state.energy_burst / 8.0f; /* ~ 8 times less pwr */ cd->tch3_state.weak_cnt = 0; /* Init FACCH state */ cd->tch3_state.sync_id = 0; memset(&cd->tch3_state.ebits, 0x00, sizeof(sbit_t) * 104 * 4); } static int _rx_tch3_dkab(struct chan_desc *cd, struct osmo_cxvec *burst) { sbit_t ebits[8]; float toa; int rv; fprintf(stderr, "[.] DKAB\n"); rv = gmr1_dkab_demod(burst, cd->sps, -cd->freq_err, cd->tch3_state.p, ebits, &toa); fprintf(stderr, "toa=%f\n", toa); return rv; } static int _rx_tch3_facch_flush(struct chan_desc *cd) { struct tch3_state *st = &cd->tch3_state; ubit_t _ciph[96*4], *ciph; uint8_t l2[10]; ubit_t sbits[8*4]; int i, crc, conv; /* Cipher stream ? */ if (st->ciph) { ciph = _ciph; for (i=0; i<4; i++) gmr1_a5(1, cd->kc, st->bi_fn[i], 96, ciph+(96*i), NULL); } else ciph = NULL; /* Decode the burst */ crc = gmr1_facch3_decode(l2, sbits, st->ebits, ciph, &conv); fprintf(stderr, "crc=%d, conv=%d\n", crc, conv); /* Retry with ciphering ? */ if (!st->ciph && crc) { ciph = _ciph; for (i=0; i<4; i++) gmr1_a5(1, cd->kc, st->bi_fn[i], 96, ciph+(96*i), NULL); crc = gmr1_facch3_decode(l2, sbits, st->ebits, ciph, &conv); fprintf(stderr, "crc=%d, conv=%d\n", crc, conv); if (!crc) st->ciph = 1; } /* Send to GSMTap if correct */ if (!crc) _gsmtap_sendmsg(g_gti, gmr1_gsmtap_makemsg( GSMTAP_GMR1_TCH3 | GSMTAP_GMR1_FACCH, cd->fn-3, st->tn, l2, 10)); /* Parse for assignement */ if (!crc && facch3_is_ass_cmd_1(l2)) { /* Follow if we have the data */ if (cd->tch_csd) rx_tch9_init(cd, l2); } /* Clear state */ st->sync_id ^= 1; st->burst_cnt = 0; memset(st->bi_fn, 0xff, sizeof(uint32_t) * 4); memset(st->ebits, 0x00, sizeof(sbit_t) * 104 * 4); /* Done */ return 0; } static int _rx_tch3_facch(struct chan_desc *cd, struct osmo_cxvec *burst) { struct tch3_state *st = &cd->tch3_state; sbit_t ebits[104]; int rv, bi, sync_id; float toa; /* Burst index */ bi = cd->fn & 3; /* Debug */ fprintf(stderr, "[.] FACCH3 (bi=%d)\n", bi); /* Demodulate burst */ rv = gmr1_pi4cxpsk_demod( &gmr1_nt3_facch_burst, burst, cd->sps, -cd->freq_err, ebits, &sync_id, &toa, NULL ); if (rv < 0) return rv; fprintf(stderr, "toa=%.1f, sync_id=%d\n", toa, sync_id); /* Does this burst belong with previous ones ? */ if (sync_id != st->sync_id) _rx_tch3_facch_flush(cd); /* Store this burst */ memcpy(&st->ebits[104*bi], ebits, sizeof(sbit_t) * 104); st->sync_id = sync_id; st->bi_fn[bi] = cd->fn; st->burst_cnt += 1; /* Is it time to flush ? */ if (st->burst_cnt == 4) _rx_tch3_facch_flush(cd); return 0; } static int _rx_tch3_speech(struct chan_desc *cd, struct osmo_cxvec *burst) { sbit_t ebits[212]; ubit_t sbits[4], ciph[208]; uint8_t frame0[10], frame1[10]; int rv, conv[2]; float toa; /* Debug */ fprintf(stderr, "[.] TCH3\n"); /* Demodulate burst */ rv = gmr1_pi4cxpsk_demod( &gmr1_nt3_speech_burst, burst, cd->sps, -cd->freq_err, ebits, NULL, &toa, NULL ); if (rv < 0) return rv; /* Decode it */ gmr1_a5(cd->tch3_state.ciph, cd->kc, cd->fn, 208, ciph, NULL); gmr1_tch3_decode(frame0, frame1, sbits, ebits, ciph, 0, &conv[0], &conv[1]); /* More debug */ fprintf(stderr, "toa=%.1f\n", toa); fprintf(stderr, "conv=%3d,%3d\n", conv[0], conv[1]); fprintf(stderr, "frame0=%s\n", osmo_hexdump_nospc(frame0, 10)); fprintf(stderr, "frame1=%s\n", osmo_hexdump_nospc(frame1, 10)); return 0; } static int rx_tch3(struct chan_desc *cd) { static struct gmr1_pi4cxpsk_burst *burst_types[] = { &gmr1_nt3_facch_burst, &gmr1_nt3_speech_burst, NULL }; struct osmo_cxvec _burst, *burst = &_burst; int e_toa, rv, btid, sid; float be, det, toa; /* Is TCH active at all ? */ if (!cd->tch3_state.active) return 0; /* Map potential burst (use FACCH3 as reference) */ e_toa = burst_map(burst, cd, &gmr1_nt3_facch_burst, cd->tch3_state.tn, cd->sps + (cd->sps/2), 1); if (e_toa < 0) return e_toa; /* Burst energy (and check for DKAB) */ be = burst_energy(burst); det = (cd->tch3_state.energy_dkab + cd->tch3_state.energy_burst) / 4.0f; if (be < det) { rv = _rx_tch3_dkab(cd, burst); if (rv < 0) return rv; else if (rv == 1) { if (cd->tch3_state.weak_cnt++ > 8) { fprintf(stderr, "END @%d\n", cd->fn); cd->tch3_state.active = 0; } } else { cd->tch3_state.energy_dkab = (0.1f * be) + (0.9f * cd->tch3_state.energy_dkab); } return 0; } else cd->tch3_state.weak_cnt = 0; cd->tch3_state.energy_burst = (0.1f * be) + (0.9f * cd->tch3_state.energy_burst); /* Detect burst type */ rv = gmr1_pi4cxpsk_detect( burst_types, (float)e_toa, burst, cd->sps, -cd->freq_err, &btid, &sid, &toa ); if (rv < 0) return rv; /* Delegate appropriately */ if (btid == 0) rv = _rx_tch3_facch(cd, burst); else rv = _rx_tch3_speech(cd, burst); /* Done */ return rv; } /* Procesing -------------------------------------------------------------- */ static int fcch_single_init(struct chan_desc *cd) { struct osmo_cxvec _win, *win = &_win; int rv, toa; /* FCCH rough detection in the first 330 ms */ rv = win_map(win, cd->bcch, cd->align, (330 * GMR1_SYM_RATE * cd->sps) / 1000); if (rv) { fprintf(stderr, "[!] Not enough samples\n"); return rv; } rv = gmr1_fcch_rough(fcch_type, win, cd->sps, 0.0f, &toa); if (rv) { fprintf(stderr, "[!] Error during FCCH rough acquisition (%d)\n", rv); return rv; } cd->align += toa; /* Fine FCCH detection*/ win_map(win, cd->bcch, cd->align, fcch_type->len * cd->sps); rv = gmr1_fcch_fine(fcch_type, win, cd->sps, 0.0f, &toa, &cd->freq_err); if (rv) { fprintf(stderr, "[!] Error during FCCH fine acquisition (%d)\n", rv); return rv; } cd->align += toa; /* Done */ return 0; } typedef int (*fcch_multi_cb_t)(struct chan_desc *cd); static int fcch_multi_process(struct chan_desc *cd, fcch_multi_cb_t cb) { struct osmo_cxvec _win, *win = &_win; int base_align, mtoa[16]; int i, j, rv, n_fcch; float ref_snr, ref_freq_err; fprintf(stderr, "[+] FCCH multi acquisition\n"); /* Multi FCCH detection (need 650 ms of signals) */ base_align = cd->align - fcch_type->len * cd->sps; if (base_align < 0) base_align = 0; rv = win_map(win, cd->bcch, base_align, (650 * GMR1_SYM_RATE * cd->sps) / 1000); if (rv) { fprintf(stderr, "[!] Not enough samples\n"); return rv; } rv = gmr1_fcch_rough_multi(fcch_type, win, cd->sps, -cd->freq_err, mtoa, 16); if (rv < 0) { fprintf(stderr, "[!] Error during FCCH rough mutli-acquisition (%d)\n", rv); return rv; } n_fcch = rv; /* Check each of them for validity */ ref_snr = ref_freq_err = 0.0f; for (i=0, j=0; ibcch, base_align + mtoa[i], fcch_type->len * cd->sps); rv = gmr1_fcch_fine(fcch_type, win, cd->sps, -cd->freq_err, &toa, &freq_err); if (rv) { fprintf(stderr, "[!] Error during FCCH fine acquisition (%d)\n", rv); return rv; } /* Compute SNR */ win_map(win, cd->bcch, base_align + mtoa[i] + toa, fcch_type->len * cd->sps ); rv = gmr1_fcch_snr(fcch_type, win, cd->sps, -(cd->freq_err + freq_err), &snr); if (rv) { fprintf(stderr, "[!] Error during FCCH SNR estimation (%d)\n", rv); } /* Check against strongest */ if (i==0) { /* This _is_ the reference */ ref_snr = snr; ref_freq_err = freq_err; } else { /* Check if SNR is 'good enough' */ if (snr < 2.0f) continue; if (snr < (ref_snr / 6.0f)) continue; /* Check if frequency error is not too "off" */ if (to_hz(fabs(ref_freq_err - freq_err)) > 500.0f) continue; } /* Debug print */ fprintf(stderr, "[.] Potential FCCH @%d (%.3f ms). [snr = %.1f dB, freq_err = %.1f Hz]\n", base_align + mtoa[i] + toa, to_ms(cd, base_align + mtoa[i] + toa), to_db(snr), to_hz(freq_err + cd->freq_err) ); /* Save it */ mtoa[j++] = mtoa[i] + toa; } n_fcch = j; /* Now process each survivor */ for (i=0; ialign = base_align + mtoa[i]; rv = cb(cdl); if (rv) break; } return rv; } static int rx_bcch(struct chan_desc *cd, float *energy) { struct osmo_cxvec _burst, *burst = &_burst; sbit_t ebits[424]; uint8_t l2[24]; float freq_err, toa; int rv, crc, conv, e_toa; /* Debug */ fprintf(stderr, "[.] BCCH\n"); /* Demodulate burst */ e_toa = burst_map(burst, cd, &gmr1_bcch_burst, cd->sa_bcch_stn, 20 * cd->sps, 0); if (e_toa < 0) return e_toa; rv = gmr1_pi4cxpsk_demod( &gmr1_bcch_burst, burst, cd->sps, -cd->freq_err, ebits, NULL, &toa, &freq_err ); if (rv) return rv; /* Measure energy as a reference */ if (energy) *energy = burst_energy(burst); /* Decode burst */ crc = gmr1_bcch_decode(l2, ebits, &conv); fprintf(stderr, "crc=%d, conv=%d\n", crc, conv); /* If burst turned out OK, use data to align channel */ if (!crc) { /* SDR alignement */ cd->align += ((int)roundf(toa)) - e_toa; cd->freq_err += freq_err; /* Acquire TDMA alignement */ bcch_tdma_align(cd, l2); } /* Send to GSMTap if correct */ if (!crc) _gsmtap_sendmsg(g_gti, gmr1_gsmtap_makemsg( GSMTAP_GMR1_BCCH, cd->fn, cd->sa_bcch_stn, l2, 24)); return 0; } static int rx_ccch(struct chan_desc *cd, float min_energy) { struct osmo_cxvec _burst, *burst = &_burst; sbit_t ebits[432]; uint8_t l2[24]; int rv, crc, conv, e_toa; /* Map potential burst */ e_toa = burst_map(burst, cd, &gmr1_dc6_burst, cd->sa_bcch_stn, 10 * cd->sps, 0); if (e_toa < 0) return e_toa; /* Energy detection */ if (burst_energy(burst) < min_energy) return 0; /* Nothing to do */ /* Debug */ fprintf(stderr, "[.] CCCH\n"); /* Demodulate burst */ rv = gmr1_pi4cxpsk_demod( &gmr1_dc6_burst, burst, cd->sps, -cd->freq_err, ebits, NULL, NULL, NULL ); if (rv) return rv; /* Decode burst */ crc = gmr1_ccch_decode(l2, ebits, &conv); fprintf(stderr, "crc=%d, conv=%d\n", crc, conv); /* Check for IMM.ASS */ if (!crc) { if (ccch_is_imm_ass(l2)) { rx_tch3_init(cd, l2, min_energy); fprintf(stderr, "\n[+] TCH3 assigned on TN %d\n", cd->tch3_state.tn); } } /* Send to GSMTap if correct */ if (!crc) _gsmtap_sendmsg(g_gti, gmr1_gsmtap_makemsg( GSMTAP_GMR1_CCCH, cd->fn, cd->sa_bcch_stn, l2, 24)); return 0; } static int process_bcch(struct chan_desc *cd) { int frame_len; int sirfn; float bcch_energy = nan("inf"); fprintf(stderr, "[+] Processing BCCH @%d (%.3f ms). [freq_err = %.1f Hz]\n", cd->align, to_ms(cd, cd->align), to_hz(cd->freq_err)); /* Process frame by frame */ frame_len = cd->sps * 24 * 39; while (1) { /* Debug */ fprintf(stderr, "[-] FN: %6d (%10.3f ms)\n", cd->fn, to_ms(cd, cd->align)); /* SI relative frame number inside an hyperframe */ sirfn = (cd->fn - cd->sa_sirfn_delay) & 63; /* BCCH */ if (sirfn % 8 == 2) rx_bcch(cd, &bcch_energy); /* CCCH */ if ((sirfn % 8 != 0) && (sirfn % 8 != 2)) rx_ccch(cd, bcch_energy / 2.0f); /* TCH */ rx_tch3(cd); rx_tch9(cd); /* Next frame */ cd->fn++; cd->align += frame_len; /* Stop if we don't have 2 complete frame * (with TN offset, we can go beyond one) */ if ((cd->align + 2*frame_len) > cd->bcch->len) break; } return 0; } /* Main ------------------------------------------------------------------- */ int main(int argc, char *argv[]) { struct chan_desc _cd, *cd = &_cd; int rv=0; /* Init channel description */ memset(cd, 0x00, sizeof(struct chan_desc)); cd->align = START_DISCARD; cd->freq_err = 0.0f; /* Arg check */ if (argc < 3 || argc > 6) { fprintf(stderr, "Usage: %s sps bcch.cfile [tch.cfile [key [tch_csd.cfile]]]\n", argv[0]); return -EINVAL; } cd->sps = atoi(argv[1]); if (cd->sps < 1 || cd->sps > 16) { fprintf(stderr, "[!] sps must be within [1,16]\n"); return -EINVAL; } cd->bcch = cfile_load(argv[2]); if (!cd->bcch) { fprintf(stderr, "[!] Failed to load bcch input file\n"); rv = -EIO; goto err; } if (argc > 3) { cd->tch = cfile_load(argv[3]); if (!cd->tch) { fprintf(stderr, "[!] Failed to load tch input file\n"); rv = -EIO; goto err; } } if (argc > 4) { if (osmo_hexparse(argv[4], cd->kc, 8) != 8) { fprintf(stderr, "[!] Invalid key\n"); rv = -EINVAL; goto err; } } if (argc > 5) { cd->tch_csd = cfile_load(argv[5]); if (!cd->tch_csd) { fprintf(stderr, "[!] Failed to load tch CSD input file\n"); rv = -EIO; goto err; } } /* Init GSMTap */ g_gti = gsmtap_source_init("127.0.0.1", GSMTAP_UDP_PORT, 0); gsmtap_source_add_sink(g_gti); /* Use best FCCH for inital sync / freq error */ rv = fcch_single_init(cd); if (rv) { fprintf(stderr, "[!] Failed to acquired primary FCCH\n"); goto err; } fprintf(stderr, "[+] Primary FCCH found @%d (%.3f ms). [freq_err = %.1f Hz]\n", cd->align, to_ms(cd, cd->align), to_hz(cd->freq_err)); /* Detect all 'visible' FCCH and process them */ rv = fcch_multi_process(cd, process_bcch); if (rv) goto err; /* Done ! */ rv = 0; /* Clean up */ err: if (cd->tch_csd) cfile_release(cd->tch_csd); if (cd->tch) cfile_release(cd->tch); if (cd->bcch) cfile_release(cd->bcch); return rv; }