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This package supports the parsing of AIS messages in Java. AIS, the Automatic Identification System, is a system aiming at improving maritime safety by exchanging messages between ships, other vehicles in particular aircraft involved in search-and-rescue (SAR), and (fixed) base stations. To be precise, this package support the ITU-R M.1371-4 AIS standard. See our extensive javadoc and in particular the class AISParser for more information on how to use this package. The parser was used in the Poseidon project, and is improved in the Metis project to better handle uncertain information. Both projects were led by the Embedded Systems Institute. In both projects Thales Nederlands was the carrying industrial partner, and multiple Dutch universities participated.

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package nl.esi.metis.aisparser;

/* ESI AIS Parser
 * 
 * Copyright 2011/2012 by Pierre van de Laar, Pierre America (Embedded Systems Institute)
 * Copyright 2008 by Brian C. Lane 
 * All Rights Reserved
 */

/** This class represents the destination area that is returned by {@link AISMessage22#getDestination} or {@link AISMessage23#getDestinationArea}.
 * @author Pierre van de Laar
 * @author Pierre America
 * @author Brian C. Lane
 */
public class DestinationArea extends Destination {
	private double       	   lon_UR;               // 18 bits : Long in degrees	Upper Right corner (north east)
	private double       	   lat_UR;               // 17 bits : Lat in degrees    Upper Right corner (north east)
	private double       	   lon_LL;               // 18 bits : Long in degrees	Lower Left corner (South West)
	private double       	   lat_LL;               // 17 bits : Lat in degrees    Lower Left corner (South West)

	/** Returns the longitude of the upper right corner of the area. 
	 * This value can be analyzed further with utility class {@link UtilsPositionInfo}.
	 * @return a double value representing the longitude in degrees (±180°, East = positive, West = negative).
	 */
	public double longitudeUpperRightCornerInDegrees() { return this.lon_UR; }

	/** Returns the latitude of the upper right corner of the area. 
	 * This value can be analyzed further with utility class {@link UtilsPositionInfo}.
	 * @return a double value representing the latitude in 1/10 minute (±90°, North = positive, South = negative).
	 */
	public double latitudeUpperRightCornerInDegrees() { return this.lat_UR; }

	/** Returns the longitude of the lower left corner of the area. 
	 * This value can be analyzed further with utility class {@link UtilsPositionInfo}.
	 * @return a double value representing the longitude in degrees (±180°, East = positive, West = negative).
	 */
	public double longitudeLowerLeftCornerInDegrees() { return this.lon_LL; }

	/** Returns the latitude of the lower left corner of the area. 
	 * This value can be analyzed further with utility class {@link UtilsPositionInfo}.
	 * @return a double value representing the latitude in degrees (±90°, North = positive, South = negative).
	 */
	public double latitudeLowerLeftCornerInDegrees() { return this.lat_LL; }

	/** Constructs a DestinationArea object.
	 * This constructor is used in the implementation classes.
	 * @param offset the offset from the beginning of the AIS message where the destination area starts.
	 * @param content the content of the AIS message
	 */
	public DestinationArea (int offset, Sixbit content)
	{
		lon_UR = UtilsLongitude18.toDegrees( UtilsTwosComplement.convertFrom18Bits( content.getIntFromTo(offset,offset+17) ) );
		lat_UR = UtilsLatitude17.toDegrees( UtilsTwosComplement.convertFrom17Bits( content.getIntFromTo(offset+18,offset+34) ) ); 
		
		lon_LL = UtilsLongitude18.toDegrees( UtilsTwosComplement.convertFrom18Bits( content.getIntFromTo(offset+35, offset+52) ) );
		lat_LL = UtilsLatitude17.toDegrees( UtilsTwosComplement.convertFrom17Bits( content.getIntFromTo(offset+53, offset+69) ) );
	}
}