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/*
* 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.
*/
#include "ax25.hpp"
#include "portapack_shared_memory.hpp"
namespace ax25 {
void AX25Frame::make_extended_field(char* const data, size_t length) {
size_t i = 0;
for (i = 0; i < length - 1; i++)
add_data(data[i] << 1);
add_data((data[i] << 1) | 1);
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}
void AX25Frame::NRZI_add_bit(const uint32_t bit) {
if (!bit)
current_bit ^= 1; // Zero: flip
current_byte <<= 1;
current_byte |= current_bit;
bit_counter++;
if (bit_counter == 8) {
bit_counter = 0;
*bb_data_ptr = current_byte;
bb_data_ptr++;
}
}
void AX25Frame::add_byte(uint8_t byte, bool is_flag, bool is_data) {
bool bit;
if (is_data)
crc_ccitt.process_byte(byte);
for (uint32_t i = 0; i < 8; i++) {
bit = (byte >> i) & 1;
NRZI_add_bit(bit);
if (bit) {
ones_counter++;
if ((ones_counter == 5) && (!is_flag)) {
NRZI_add_bit(0);
ones_counter = 0;
}
} else
ones_counter = 0;
}
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}
void AX25Frame::flush() {
if (bit_counter)
*bb_data_ptr = current_byte << (8 - bit_counter); // euquiq: This was 7 but there are 8 bits
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};
void AX25Frame::add_flag() {
add_byte(AX25_FLAG, true, false);
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};
void AX25Frame::add_data(uint8_t byte) {
add_byte(byte, false, true);
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};
void AX25Frame::add_checksum() {
auto checksum = crc_ccitt.checksum();
add_byte(checksum, false, false);
add_byte(checksum >> 8, false, false);
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}
void AX25Frame::make_ui_frame(char* const address, const uint8_t control, const uint8_t protocol, const std::string& info) {
size_t i;
bb_data_ptr = (uint16_t*)shared_memory.bb_data.data;
memset(bb_data_ptr, 0, sizeof(shared_memory.bb_data.data));
bit_counter = 0;
current_bit = 0;
current_byte = 0;
ones_counter = 0;
crc_ccitt.reset();
add_flag();
add_flag();
add_flag();
add_flag();
make_extended_field(address, 14);
add_data(control);
add_data(protocol);
for (i = 0; i < info.size(); i++)
add_data(info[i]);
add_checksum();
add_flag();
add_flag();
flush();
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}
} /* namespace ax25 */