HackRF-Treasure-Chest/Software/portapack-mayhem/firmware/common/adsb_frame.hpp
2022-09-22 09:26:57 -07:00

132 lines
3.1 KiB
C++

/*
* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
* Copyright (C) 2017 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.
*/
#ifndef __ADSB_FRAME_H__
#define __ADSB_FRAME_H__
#include <cstring>
#include <string>
namespace adsb {
alignas(4) const uint8_t adsb_preamble[16] = { 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0 };
alignas(4) const char icao_id_lut[65] = "#ABCDEFGHIJKLMNOPQRSTUVWXYZ##### ###############0123456789######";
class ADSBFrame {
public:
uint8_t get_DF() {
return (raw_data[0] >> 3);
}
uint8_t get_msg_type() {
return (raw_data[4] >> 3);
}
uint8_t get_msg_sub() {
return (raw_data[4] & 7);
}
uint32_t get_ICAO_address() {
return (raw_data[1] << 16) + (raw_data[2] << 8) + raw_data[3];
}
void set_rx_timestamp(uint32_t timestamp) {
rx_timestamp = timestamp;
}
uint32_t get_rx_timestamp() {
return rx_timestamp;
}
void clear() {
index = 0;
memset(raw_data, 0, 14);
}
void push_byte(uint8_t byte) {
if (index >= 14)
return;
raw_data[index++] = byte;
}
uint8_t * get_raw_data() const {
return (uint8_t* )raw_data;
}
void make_CRC() {
uint32_t computed_CRC = compute_CRC();
// Insert CRC in frame
raw_data[11] = (computed_CRC >> 16) & 0xFF;
raw_data[12] = (computed_CRC >> 8) & 0xFF;
raw_data[13] = computed_CRC & 0xFF;
}
bool check_CRC() {
uint32_t computed_CRC = compute_CRC();
if ((raw_data[11] != ((computed_CRC >> 16) & 0xFF)) ||
(raw_data[12] != ((computed_CRC >> 8) & 0xFF)) ||
(raw_data[13] != (computed_CRC & 0xFF))) return false;
return true;
}
bool empty() {
return (index == 0);
}
private:
static const uint8_t adsb_preamble[16];
static const char icao_id_lut[65];
alignas(4) uint8_t index { 0 };
alignas(4) uint8_t raw_data[14] { }; // 112 bits at most
uint32_t rx_timestamp { };
uint32_t compute_CRC() {
uint8_t adsb_crc[14] = { 0 }; // Temp buffer
uint8_t b, c, s, bitn;
const uint32_t crc_poly = 0x1205FFF;
// Copy frame data
memcpy(adsb_crc, raw_data, 11);
// Compute CRC
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));
}
}
}
}
return (adsb_crc[11] << 16) + (adsb_crc[12] << 8) + adsb_crc[13];
}
};
} /* namespace adsb */
#endif/*__ADSB_FRAME_H__*/