mirror of
https://github.com/eried/portapack-mayhem.git
synced 2024-10-01 01:26:06 -04:00
121 lines
2.6 KiB
C++
121 lines
2.6 KiB
C++
/*
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* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
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* Copyright (C) 2017 Furrtek
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "ax25.hpp"
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#include "portapack_shared_memory.hpp"
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namespace ax25 {
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void AX25Frame::make_extended_field(char * const data, size_t length) {
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size_t i = 0;
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for (i = 0; i < length - 1; i++)
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add_data(data[i] << 1);
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add_data((data[i] << 1) | 1);
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}
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void AX25Frame::add_byte(uint8_t byte, bool is_flag, bool is_data) {
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size_t i;
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for (i = 0; i < 8; ) {
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if (!(byte & 1)) {
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current_bit ^= 1; // Zero: flip
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ones_counter = 0;
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byte >>= 1;
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i++;
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} else {
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ones_counter++;
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if ((ones_counter == 5) && (!is_flag)) {
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current_bit ^= 1; // Stuff zero: flip
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ones_counter = 0;
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} else {
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byte >>= 1;
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i++;
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}
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}
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if (is_data)
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crc_ccitt.process_bit(current_bit);
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current_byte <<= 1;
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current_byte |= current_bit;
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if (bit_counter == 7) {
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bit_counter = 0;
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*bb_data_ptr = current_byte;
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bb_data_ptr++;
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} else {
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bit_counter++;
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}
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}
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}
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void AX25Frame::flush() {
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if (bit_counter)
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*bb_data_ptr = current_byte << (7 - bit_counter);
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};
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void AX25Frame::add_flag() {
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add_byte(AX25_FLAG, true, false);
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};
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void AX25Frame::add_data(uint8_t byte) {
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add_byte(byte, false, true);
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};
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void AX25Frame::add_checksum() {
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auto checksum = crc_ccitt.checksum();
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add_byte(checksum >> 8, false, false);
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add_byte(checksum, false, false);
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}
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void AX25Frame::make_ui_frame(char * const address, const uint8_t control,
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const uint8_t protocol, uint8_t * const info, size_t length) {
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size_t i;
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bb_data_ptr = shared_memory.bb_data.data;
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bit_counter = 0;
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current_bit = 0;
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current_byte = 0;
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ones_counter = 0;
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crc_ccitt.reset();
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add_flag();
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make_extended_field(address, 14);
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add_data(control);
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add_data(protocol);
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for (i = 0; i < length; i++)
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add_data(info[i]);
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add_checksum();
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add_flag();
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flush();
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}
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} /* namespace ax25 */
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