msgbuffer.h

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/*
 * libmavconn
 * Copyright 2014,2015,2016 Vladimir Ermakov, All rights reserved.
 *
 * This file is part of the mavros package and subject to the license terms
 * in the top-level LICENSE file of the mavros repository.
 * https://github.com/mavlink/mavros/tree/master/LICENSE.md
 */
 
#pragma once
 
#include <cassert>
#include <mavconn/mavlink_dialect.h>
 
namespace mavconn {
struct MsgBuffer {
        static constexpr ssize_t MAX_SIZE = MAVLINK_MAX_PACKET_LEN + 16;
        uint8_t data[MAX_SIZE];
        ssize_t len;
        ssize_t pos;
 
        MsgBuffer() :
                len(0),
                pos(0)
        { }
 
        explicit MsgBuffer(const mavlink::mavlink_message_t *msg) :
                pos(0)
        {
                len = mavlink::mavlink_msg_to_send_buffer(data, msg);
                // paranoic check, it must be less than MAVLINK_MAX_PACKET_LEN
                assert(len < MAX_SIZE);
        }
 
        MsgBuffer(const mavlink::Message &obj, mavlink::mavlink_status_t *status, uint8_t sysid, uint8_t compid) :
                pos(0)
        {
                mavlink::mavlink_message_t msg;
                mavlink::MsgMap map(msg);
 
                auto mi = obj.get_message_info();
 
                obj.serialize(map);
                mavlink::mavlink_finalize_message_buffer(&msg, sysid, compid, status, mi.min_length, mi.length, mi.crc_extra);
 
                len = mavlink::mavlink_msg_to_send_buffer(data, &msg);
                // paranoic check, it must be less than MAVLINK_MAX_PACKET_LEN
                assert(len < MAX_SIZE);
        }
 
        MsgBuffer(const uint8_t *bytes, ssize_t nbytes) :
                len(nbytes),
                pos(0)
        {
                assert(0 < nbytes && nbytes < MAX_SIZE);
                memcpy(data, bytes, nbytes);
        }
 
        virtual ~MsgBuffer() {
                pos = 0;
                len = 0;
        }
 
        uint8_t *dpos() {
                return data + pos;
        }
 
        ssize_t nbytes() {
                return len - pos;
        }
};
}       // namespace mavconn