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/*
* Copyright 2021 Chipeng Li (chplee@gmail.com)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.traccar.protocol;
import java.net.SocketAddress;
import java.time.Instant;
import java.util.Date;
import org.traccar.BaseProtocolDecoder;
import org.traccar.DeviceSession;
import org.traccar.Protocol;
import org.traccar.helper.UnitsConverter;
import org.traccar.model.Position;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
public class Mavlink2ProtocolDecoder extends BaseProtocolDecoder {
public Mavlink2ProtocolDecoder(Protocol protocol) {
super(protocol);
}
@Override
protected Object decode(Channel channel, SocketAddress remoteAddress, Object msg) throws Exception {
ByteBuf buf = (ByteBuf) msg;
if (buf.readUnsignedByte() != 0xFD) { //Packet start marker
return null;
}
buf.readUnsignedByte(); // Payload length
buf.readUnsignedByte(); // Incompatibility Flags
buf.readUnsignedByte(); // Compatibility Flags
buf.readUnsignedByte(); // Packet sequence number
int senderSystemId = buf.readUnsignedByte(); // System ID (sender)
DeviceSession deviceSession = getDeviceSession(channel, remoteAddress, Integer.toString(senderSystemId));
buf.readUnsignedByte(); // Component ID (sender)
if (deviceSession == null) {
return null;
}
int messageId = buf.readUnsignedMediumLE(); // Message ID (low, middle, high bytes)
if (messageId == 33) {
Position position = new Position(getProtocolName());
position.setDeviceId(deviceSession.getDeviceId());
position.setValid(true);
position.setTime(Date.from(Instant.now()));
position.set("timeBootms", buf.readUnsignedIntLE()); // Timestamp (time since system boot).
position.setLatitude(buf.readIntLE() / 10000000.0);
position.setLongitude(buf.readIntLE() / 10000000.0);
position.setAltitude(buf.readIntLE() / 1000.0); // Altitude (MSL).
position.set("relativeAltitude", buf.readIntLE() / 1000.0); // Altitude above ground
int groundSpeedX = buf.readShortLE();
int groundSpeedY = buf.readShortLE();
buf.readShortLE(); // Ground Z Speed
double speed = Math.sqrt(Math.pow(groundSpeedX, 2) + Math.pow(groundSpeedY, 2));
position.setSpeed(UnitsConverter.knotsFromCps(speed));
position.setCourse(buf.readUnsignedShortLE() / 100.0);
return position;
}
return null;
}
}
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