portapack-mayhem/firmware/application/protocols/ax25.hpp

/*
 * 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 "crc.hpp"

#include <cstring>
#include <string>

#ifndef __AX25_H__
#define __AX25_H__

#define AX25_FLAG 0x7E

namespace ax25 {

enum protocol_id_t {
    X25_PLP = 0x01,
    COMP_TCPIP = 0x06,
    UNCOMP_TCPIP = 0x07,
    SEG_FRAG = 0x08,
    FLEXNET = 0xCE,
    NO_LAYER3 = 0xF0
};

class AX25Frame {
   public:
    void make_ui_frame(char* const address, const uint8_t control, const uint8_t protocol, const std::string& info);

   private:
    void NRZI_add_bit(const uint32_t bit);
    void make_extended_field(char* const data, size_t length);
    void add_byte(uint8_t byte, bool is_flag, bool is_data);
    void add_data(uint8_t byte);
    void add_checksum();
    void add_flag();
    void flush();

    uint16_t* bb_data_ptr{nullptr};
    uint8_t current_bit{0};
    uint8_t current_byte{0};
    size_t bit_counter{0};
    uint8_t ones_counter{0};

    CRC<16, true, true> crc_ccitt{0x1021, 0xFFFF, 0xFFFF};
};

} /* namespace ax25 */

#endif /*__AX25_H__*/