/* * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc. * Copyright (C) 2016 Furrtek * * This file is part of PortaPack. * * 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, 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. * * You should have received a copy of the GNU General Public License * along with this program; see the file COPYING. If not, write to * the Free Software Foundation, Inc., 51 Franklin Street, * Boston, MA 02110-1301, USA. */ #include "adsb.hpp" #include "portapack_persistent_memory.hpp" namespace adsb { void make_frame_mode_s(uint8_t * const adsb_frame, const uint32_t ICAO_address) { adsb_frame[0] = (17 << 3) | 5; // DF and CA adsb_frame[1] = ICAO_address >> 16; adsb_frame[2] = (ICAO_address >> 8) & 0xFF; adsb_frame[3] = ICAO_address & 0xFF; memset(&adsb_frame[4], 0, 10); } void generate_frame_id(uint8_t * const adsb_frame, const uint32_t ICAO_address, std::string & callsign) { std::string callsign_formatted(8, '_'); uint64_t callsign_coded = 0; uint32_t c, s; char ch; make_frame_mode_s(adsb_frame, ICAO_address); adsb_frame[4] = 4 << 3; // TC = 4: Aircraft ID // Translate and encode callsign for (c = 0; c < 8; c++) { ch = callsign[c]; for (s = 0; s < 64; s++) if (ch == icao_id_lut[s]) break; if (s >= 64) { ch = ' '; // Invalid character s = 32; } callsign_coded |= ((uint64_t)s << ((7 - c) * 6)); callsign[c] = ch; } // Insert callsign in frame for (c = 0; c < 6; c++) adsb_frame[c + 5] = (callsign_coded >> ((5 - c) * 8)) & 0xFF; ADSB_generate_CRC(adsb_frame); } void generate_frame_emergency(uint8_t * const adsb_frame, const uint32_t ICAO_address, const uint8_t code) { make_frame_mode_s(adsb_frame, ICAO_address); adsb_frame[4] = (28 << 3) + 1; // TC = 28 (Emergency), subtype = 1 (Emergency) adsb_frame[5] = code << 5; ADSB_generate_CRC(adsb_frame); } /* void generate_frame_pos(uint8_t * const adsb_frame, const uint32_t ICAO_address, const uint32_t altitude, const float latitude, const float longitude) { uint8_t c, time_parity; uint32_t altitude_coded; uint32_t LAT, LON; float delta_lat, yz, rlat, delta_lon, xz; LAT = 0; make_frame_mode_s(adsb_frame, ICAO_address); adsb_frame[4] = 11 << 3; // TC = 11: Airborne position altitude_coded = (altitude + 1000) / 25; // Can be coded in 100ft steps also // LAT: // index j = floor(59*latcprE-60*latcprO+0.50) // latE = DlatE*(mod(j,60)+latcprE) // latO = DlatO*(mod(j,59)+latcprO) // if latE >= 270 -> latE -= 360 // if latO >= 270 -> latO -= 360 //time_parity = 0; // 0~1 //delta_lat = 90.0 / (60.0 - (time_parity / 4.0)); //yz = 524288.0 * (mod(lat, delta_lat) / delta_lat); // Round to int ! //rlat = delta_lat * ((yz / 524288.0) + int(lat / delta_lat)); //delta_lon = 360.0 / (NL(rlat) - time_parity); //xz = 524288.0 * (mod(lon, delta_lon) / delta_lon); // Round to int ! if (time_parity) { A = sign(rlat0)[NL(rlat0) - NL(rlat1)]; } // int xz and yz, then: // xz >>= 2; // yz >>= 2; // To get 17 bits // aaaaaaa Q bbbb adsb_frame[5] = ((altitude_coded & 0x7F0) >> 3) | 1; adsb_frame[6] = ((altitude_coded & 0x00F) << 4) | (LAT >> 15); // Then 0, even/odd, and the 2 LAT-CPR MSBs } */ void ADSB_generate_CRC(uint8_t * const in_frame) { uint8_t adsb_crc[14]; // Temp buffer uint8_t b, c, s, bitn; const uint32_t crc_poly = 0x1205FFF; // Clear CRC in_frame[11] = 0x00; in_frame[12] = 0x00; in_frame[13] = 0x00; // Compute CRC memcpy(adsb_crc, in_frame, 14); for (c = 0; c < 11; c++) { for (b = 0; b < 8; b++) { if ((adsb_crc[c] << b) & 0x80) { for (s = 0; s < 25; s++) { bitn = (c * 8) + b + s; if ((crc_poly >> s) & 1) adsb_crc[bitn >> 3] ^= (0x80 >> (bitn & 7)); } } } } // Insert CRC in frame memcpy(&in_frame[11], &adsb_crc[11], 3); } } /* namespace adsb */