mirror of
https://github.com/portapack-mayhem/mayhem-firmware.git
synced 2024-12-13 19:54:39 +00:00
133 lines
3.5 KiB
C++
133 lines
3.5 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>
|
|
#include <cstdint>
|
|
|
|
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__*/
|