108 lines
2.6 KiB
C++

/*
* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
* Copyright (C) 2018 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 "acars_packet.hpp"
#include "crc.hpp"
#include <cstdlib>
namespace acars {
size_t Packet::length() const {
return packet_.size();
}
bool Packet::is_valid() const {
return true; //length_valid() && crc_ok();
}
Timestamp Packet::received_at() const {
return packet_.timestamp();
}
uint8_t Packet::block_id() const {
return field_.read(96, 8);
}
std::string Packet::registration_number() const {
std::string result;
result.reserve(7);
const size_t character_length = 8;
for(size_t i=16; i<(16+7*character_length); i+=character_length) {
result += (field_.read(i, character_length) & 0x7F);
}
return result;
}
uint32_t Packet::read(const size_t start_bit, const size_t length) const {
return field_.read(start_bit, length);
}
/*std::string Packet::text(
const size_t start_bit,
const size_t character_count
) const {
std::string result;
result.reserve(character_count);
const size_t character_length = 6;
const size_t end_bit = start_bit + character_count * character_length;
for(size_t i=start_bit; i<end_bit; i+=character_length) {
result += char_to_ascii(field_.read(i, character_length));
}
return result;
}*/
bool Packet::crc_ok() const {
CRCReader field_crc { packet_ };
CRC<16> acars_fcs { 0x1021, 0x0000, 0x0000 };
for(size_t i=0; i<data_length(); i+=8) {
acars_fcs.process_byte(field_crc.read(i, 8));
}
return (acars_fcs.checksum() == (unsigned)field_crc.read(data_length(), fcs_length));
}
size_t Packet::data_and_fcs_length() const {
return length() - 8;
}
size_t Packet::data_length() const {
return data_and_fcs_length() - fcs_length;
}
bool Packet::length_valid() const {
const size_t extra_bits = data_and_fcs_length() & 7;
if( extra_bits != 0 ) {
return false;
}
return true;
}
} /* namespace ais */