Started work on APRS (AX25)

firmware/application/protocols/ax25.hpp

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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 "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,
+						uint8_t * const info, size_t length);
+	
+private:
+	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();
+	
+	uint8_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> crc_ccitt { 0x1021, 0xFFFF };
+};
+
+} /* namespace ax25 */
+
+#endif/*__AX25_H__*/