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messages.go
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messages.go
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package ais
import (
"reflect"
)
type processFunc func(packet Packet) Packet
type msgMapType struct {
rType reflect.Type
}
var msgMap [28]msgMapType
// Packet is an interface describing coded and decoded ais packets
type Packet interface {
GetHeader() *Header
}
// Header contains the header prepended to each packet
type Header struct {
MessageID uint8 `aisWidth:"6"`
RepeatIndicator uint8 `aisWidth:"2"`
UserID uint32 `aisWidth:"30"`
}
// GetHeader returns the header of the packet
func (h Header) GetHeader() *Header {
return &h
}
// PositionReport should be output periodically by mobile stations. The message ID is 1, 2 or 3
// depending on the system mode.
type PositionReport struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
NavigationalStatus uint8 `aisWidth:"4"`
RateOfTurn int16 `aisWidth:"8"`
Sog Field10 `aisWidth:"10"`
PositionAccuracy bool `aisWidth:"1"`
Longitude FieldLatLonFine `aisWidth:"28"`
Latitude FieldLatLonFine `aisWidth:"27"`
Cog Field10 `aisWidth:"12"`
TrueHeading uint16 `aisWidth:"9"`
Timestamp uint8 `aisWidth:"6"`
SpecialManoeuvreIndicator uint8 `aisWidth:"2"`
Spare uint8 `aisWidth:"3" aisEncodeAs:"0"`
Raim bool `aisWidth:"1"`
CommunicationStateNoItdma `aisWidth:"19"`
}
// BaseStationReport should be used for reporting UTC time and date and, at the same time, position.
// A base station should use Message 4 in its periodical transmissions. Message 4 is used by AIS stations
// for determining if it is within 120 NM for response to Messages 20 and 23. A mobile station should output
// Message 11 only in response to interrogation by Message 10. Message 11 is only transmitted as a result
// of a UTC request message (Message 10). The UTC and date response should be transmitted on the channel,
// where the UTC request message was received. */
type BaseStationReport struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
UtcYear uint16 `aisWidth:"14"`
UtcMonth uint8 `aisWidth:"4"`
UtcDay uint8 `aisWidth:"5"`
UtcHour uint8 `aisWidth:"5"`
UtcMinute uint8 `aisWidth:"6"`
UtcSecond uint8 `aisWidth:"6"`
PositionAccuracy bool `aisWidth:"1"`
Longitude FieldLatLonFine `aisWidth:"28"`
Latitude FieldLatLonFine `aisWidth:"27"`
FixType uint8 `aisWidth:"4"`
LongRangeEnable bool `aisWidth:"1"`
Spare uint16 `aisWidth:"9" aisEncodeAs:"0"`
Raim bool `aisWidth:"1"`
CommunicationStateNoItdma `aisWidth:"19"`
}
// ShipStaticData should only be used by Class A shipborne and SAR aircraft AIS stations when reporting static
// or voyage related data.
type ShipStaticData struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"424"`
AisVersion uint8 `aisWidth:"2"`
ImoNumber uint32 `aisWidth:"30"`
CallSign string `aisWidth:"42"`
Name string `aisWidth:"120"`
Type uint8 `aisWidth:"8"`
Dimension FieldDimension `aisWidth:"30"`
FixType uint8 `aisWidth:"4"`
Eta FieldETA `aisWidth:"20"`
MaximumStaticDraught Field10 `aisWidth:"8"`
Destination string `aisWidth:"120"`
Dte bool `aisWidth:"1"`
Spare bool `aisWidth:"1" aisEncodeAs:"0"`
}
// AddressedBinaryMessage should be variable in length, based on the amount of binary data.
// The length should vary between 1 and 5 slots. See application identifiers in § 2.1, Annex 5.
type AddressedBinaryMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"1008"`
SequenceNumber uint8 `aisWidth:"2"`
DestinationID uint32 `aisWidth:"30"`
Retransmission bool `aisWidth:"1"`
Spare bool `aisWidth:"1" aisEncodeAs:"0"`
ApplicationID FieldApplicationIdentifier `aisWidth:"16"`
BinaryData []byte `aisWidth:"-1"`
}
// BinaryBroadcastMessage will be variable in length, based on the amount of binary data.
// The length should vary between 1 and 5 slots.
type BinaryBroadcastMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"1008"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
ApplicationID FieldApplicationIdentifier `aisWidth:"16"`
BinaryData []byte `aisWidth:"-1"`
}
// StandardSearchAndRescueAircraftReport should be used as a standard position report for
// aircraft involved in SAR operations. Stations other than aircraft involved in SAR operations
// should not transmit this message. The default reporting interval for this message should be 10 s.
type StandardSearchAndRescueAircraftReport struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
Altitude uint16 `aisWidth:"12"`
Sog uint16 `aisWidth:"10"`
PositionAccuracy bool `aisWidth:"1"`
Longitude FieldLatLonFine `aisWidth:"28"`
Latitude FieldLatLonFine `aisWidth:"27"`
Cog Field10 `aisWidth:"12"`
Timestamp uint8 `aisWidth:"6"`
AltFromBaro bool `aisWidth:"1"`
Spare1 uint8 `aisWidth:"7" aisEncodeAs:"0"`
Dte bool `aisWidth:"1"`
Spare2 uint8 `aisWidth:"3" aisEncodeAs:"0"`
AssignedMode bool `aisWidth:"1"`
Raim bool `aisWidth:"1"`
CommunicationStateItdma `aisWidth:"20"`
}
// CoordinatedUTCInquiry should be used when a station is requesting UTC and date from another
// station.
type CoordinatedUTCInquiry struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"72"`
Spare1 uint8 `aisWidth:"2" aisEncodeAs:"0"`
DestinationID uint32 `aisWidth:"30"`
Spare2 uint8 `aisWidth:"2" aisEncodeAs:"0"`
}
// AddessedSafetyMessage could be variable in length, based on the amount of safety related text.
// The length should vary between 1 and 5 slots.
type AddessedSafetyMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"1008"`
SequenceNumber uint8 `aisWidth:"2"`
DestinationID uint32 `aisWidth:"30"`
Retransmission bool `aisWidth:"1"`
Spare bool `aisWidth:"1" aisEncodeAs:"0"`
Text string `aisWidth:"-1"`
}
// SafetyBroadcastMessage could be variable in length, based on the amount of safety related
// text. The length should vary between 1 and 5 slots.
type SafetyBroadcastMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"1008"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
Text string `aisWidth:"-1"`
}
// GnssBroadcastBinaryMessage should be transmitted by a base station, which is connected to a DGNSS
// reference source, and configured to provide DGNSS data to receiving stations. The contents of the
// data should be in accordance with Recommendation ITU-R M.823, excluding preamble and parity formatting.
type GnssBroadcastBinaryMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"816"`
Spare1 uint8 `aisWidth:"2" aisEncodeAs:"0"`
Longitude FieldLatLonCoarse `aisWidth:"18"`
Latitude FieldLatLonCoarse `aisWidth:"17"`
Spare2 uint8 `aisWidth:"5" aisEncodeAs:"0"`
Data []byte `aisWidth:"-1"`
}
// StandardClassBPositionReport should be output periodically and autonomously instead of
// Messages 1, 2, or 3 by Class B shipborne mobile equipment, only. The reporting interval should default to
// the values given in Table 2, Annex 1, unless otherwise specified by reception of a Message 16 or 23; and
// depending on the current SOG and navigational status flag setting.
type StandardClassBPositionReport struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
Spare1 uint8 `aisWidth:"8" aisEncodeAs:"0"`
Sog Field10 `aisWidth:"10"`
PositionAccuracy bool `aisWidth:"1"`
Longitude FieldLatLonFine `aisWidth:"28"`
Latitude FieldLatLonFine `aisWidth:"27"`
Cog Field10 `aisWidth:"12"`
TrueHeading uint16 `aisWidth:"9"`
Timestamp uint8 `aisWidth:"6"`
Spare2 uint8 `aisWidth:"2" aisEncodeAs:"0"`
ClassBUnit bool `aisWidth:"1"`
ClassBDisplay bool `aisWidth:"1"`
ClassBDsc bool `aisWidth:"1"`
ClassBBand bool `aisWidth:"1"`
ClassBMsg22 bool `aisWidth:"1"`
AssignedMode bool `aisWidth:"1"`
Raim bool `aisWidth:"1"`
CommunicationStateItdma `aisWidth:"20"`
}
// ExtendedClassBPositionReport should be transmitted once every 6 min in two slots allocated by the
// use of Message 18 in the ITDMA communication state. This message should be transmitted immediately
// after the following parameter values change: dimension of ship/reference for position or type of
// electronic position fixing device.
// For future equipment: this message is not needed and should not be used. All content is covered by
// Message 18, Message 24A and 24B.
// For legacy equipment: this message should be used by Class B shipborne mobile equipment.
type ExtendedClassBPositionReport struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"312"`
Spare1 uint8 `aisWidth:"8" aisEncodeAs:"0"`
Sog Field10 `aisWidth:"10"`
PositionAccuracy bool `aisWidth:"1"`
Longitude FieldLatLonFine `aisWidth:"28"`
Latitude FieldLatLonFine `aisWidth:"27"`
Cog Field10 `aisWidth:"12"`
TrueHeading uint16 `aisWidth:"9"`
Timestamp uint8 `aisWidth:"6"`
Spare2 uint8 `aisWidth:"4" aisEncodeAs:"0"`
Name string `aisWidth:"120"`
Type uint8 `aisWidth:"8"`
Dimension FieldDimension `aisWidth:"30"`
FixType uint8 `aisWidth:"4"`
Raim bool `aisWidth:"1"`
Dte bool `aisWidth:"1"`
AssignedMode bool `aisWidth:"1"`
Spare3 uint8 `aisWidth:"4" aisEncodeAs:"0"`
}
// AidsToNavigationReport should be used by an Aids to navigation (AtoN) AIS station. This station
// may be mounted on an aid-to-navigation or this message may be transmitted by a fixed station when
// the functionality of an AtoN station is integrated into the fixed station. This message should be
// transmitted autonomously at a Rr of once every three (3) min or it may be assigned by an assigned
// mode command (Message 16) via the VHF data link, or by an external command. This message
// should not occupy more than two slots.
type AidsToNavigationReport struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"356"`
Type uint8 `aisWidth:"5"`
Name string `aisWidth:"120"`
PositionAccuracy bool `aisWidth:"1"`
Longitude FieldLatLonFine `aisWidth:"28"`
Latitude FieldLatLonFine `aisWidth:"27"`
Dimension FieldDimension `aisWidth:"30"`
Fixtype uint8 `aisWidth:"4"`
Timestamp uint8 `aisWidth:"6"`
OffPosition bool `aisWidth:"1"`
AtoN uint8 `aisWidth:"8"`
Raim bool `aisWidth:"1"`
VirtualAtoN bool `aisWidth:"1"`
AssignedMode bool `aisWidth:"1"`
Spare bool `aisWidth:"1" aisEncodeAs:"0"`
NameExtension string `aisWidth:"-1"`
}
// GroupAssignmentCommand is transmitted by a base station when operating as a controlling
// entity(see § 4.3.3.3.2 Annex 7 and § 3.20). This message should be applied to a mobile station within
// the defined region and as selected by “Ship and Cargo Type” or “Station type”. The receiving station
// should consider all selector fields concurrently. It controls the following operating parameters of a
// mobile station:
// * transmit/receive mode;
// * reporting interval;
// * the duration of a quiet time.
// Station type 10 should be used to define the base station coverage area for control of Message 27
// transmissions by Class A and Class B “SO” mobile stations. When station type is 10 only the fields
// latitude, longitude are used, all other fields should be ignored. This information will be relevant until
// three minutes after the last reception of controlling Message 4 from the same base station (same MMSI).
type GroupAssignmentCommand struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"160"`
Spare1 uint8 `aisWidth:"2" aisEncodeAs:"0"`
Longitude1 FieldLatLonCoarse `aisWidth:"18"`
Latitude1 FieldLatLonCoarse `aisWidth:"17"`
Longitude2 FieldLatLonCoarse `aisWidth:"18"`
Latitude2 FieldLatLonCoarse `aisWidth:"17"`
StationType uint8 `aisWidth:"4"`
ShipType uint8 `aisWidth:"8"`
Spare2 uint32 `aisWidth:"22" aisEncodeAs:"0"`
TxRxMode uint8 `aisWidth:"2"`
ReportingInterval uint8 `aisWidth:"4"`
QuietTime uint8 `aisWidth:"4"`
Spare3 uint8 `aisWidth:"6" aisEncodeAs:"0"`
}
// StaticDataReportA is the A part of message 24
type StaticDataReportA struct {
Valid bool
Name string `aisWidth:"120"`
}
// StaticDataReportB is the B part of message 24
type StaticDataReportB struct {
Valid bool
ShipType uint8 `aisWidth:"8"`
VendorIDName string `aisWidth:"18"`
VenderIDModel uint8 `aisWidth:"4"`
VenderIDSerial uint32 `aisWidth:"20"`
CallSign string `aisWidth:"42"`
Dimension FieldDimension `aisWidth:"30"`
FixType uint8 `aisWidth:"4"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
}
// StaticDataReport part A shall transmit once every 6 min alternating between
// channels.
// Message 24 Part A may be used by any AIS station to associate a MMSI with a name.
// Message 24 Part A and Part B should be transmitted once every 6 min by Class B “CS” and Class B
// “SO” shipborne mobile equipment. The message consists of two parts. Message 24B should be
// transmitted within 1 min following Message 24A.
type StaticDataReport struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
Reserved uint8 `aisWidth:"1" aisEncodeAs:"0" aisCheckValue:"0"`
PartNumber bool `aisWidth:"1"`
ReportA StaticDataReportA `aisWidth:"120" aisDependsBit:"~39" aisDependsField:"~PartNumber"`
ReportB StaticDataReportB `aisWidth:"120" aisDependsBit:"39" aisDependsField:"PartNumber"`
}
// LongRangeAisBroadcastMessage is primarily intended for long-range detection of AIS Class A
// and Class B “SO” equipped vessels (typically by satellite). This message has a similar content
// to Messages 1, 2 and 3, but the total number of bits has been compressed to allow for increased
// propagation delays associated with long-range detection. Refer to Annex 4 for details on
//Long-Range applications.
type LongRangeAisBroadcastMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"96"`
PositionAccuracy bool `aisWidth:"1"`
Raim bool `aisWidth:"1"`
NavigationalStatus uint8 `aisWidth:"4"`
Longitude FieldLatLonCoarse `aisWidth:"18"`
Latitude FieldLatLonCoarse `aisWidth:"17"`
Sog uint8 `aisWidth:"6"`
Cog uint16 `aisWidth:"9"`
PositionLatency bool `aisWidth:"1"`
Spare bool `aisWidth:"1" aisEncodeAs:"0"`
}
// BinaryAcknowledgeData is the data part of BinaryAcknowledge
type BinaryAcknowledgeData struct {
Valid bool
DestinationID uint32 `aisWidth:"30"`
SequenceNumber uint8 `aisWidth:"2"`
}
// BinaryAcknowledge should be used as an acknowledgement of up to four Message 6 messages received
// (see § 5.3.1, Annex 2) and should be transmitted on the channel, where the addressed message to be
// acknowledged was received.
type BinaryAcknowledge struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
Destinations [4]BinaryAcknowledgeData `aisWidth:"0"`
}
// InterrogationStation1Message1 is the station 1 part of Interrogation
type InterrogationStation1Message1 struct {
Valid bool
StationID uint32 `aisWidth:"30"`
MessageID uint8 `aisWidth:"6"`
SlotOffset uint16 `aisWidth:"12"`
}
// InterrogationStation1Message2 is the second station 1 part of interrogation
type InterrogationStation1Message2 struct {
Valid bool `aisOptional:"1"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
MessageID uint8 `aisWidth:"6"`
SlotOffset uint16 `aisWidth:"12"`
}
// InterrogationStation2 is the station 2 part of Interrogation
type InterrogationStation2 struct {
Valid bool `aisOptional:"1"`
Spare1 uint8 `aisWidth:"2" aisEncodeAs:"0"`
StationID uint32 `aisWidth:"30"`
MessageID uint8 `aisWidth:"6"`
SlotOffset uint16 `aisWidth:"12"`
Spare2 uint8 `aisWidth:"2" aisEncodeAs:"0"`
}
// Interrogation should be used for interrogations via the TDMA (not DSC) VHF data link except for
// requests for UTC and date. The response should be transmitted on the channel where the interrogation
// was received.
type Interrogation struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"160"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
Station1Msg1 InterrogationStation1Message1 `aisWidth:"48"`
Station1Msg2 InterrogationStation1Message2 `aisWidth:"0"`
Station2 InterrogationStation2 `aisWidth:"0"`
}
// AssignedModeCommandData is the data part of AssignedModeCommand
type AssignedModeCommandData struct {
Valid bool
DestinationID uint32 `aisWidth:"30"`
Offset uint16 `aisWidth:"12"`
Increment uint16 `aisWidth:"10"`
}
// AssignedModeCommand be transmitted by a base station when operating as a controlling entity. Other
// stations can be assigned a transmission schedule, other than the currently used one. If a station is
// assigned a schedule, it will also enter assigned mode.
type AssignedModeCommand struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"144"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
Commands [2]AssignedModeCommandData `aisWidth:"0"`
}
// DataLinkManagementMessageData is the data part of DataLinkManagementMessage
type DataLinkManagementMessageData struct {
Valid bool
Offset uint16 `aisWidth:"12"`
NumberOfSlots uint8 `aisWidth:"4"`
TimeOut uint8 `aisWidth:"3"`
Increment uint16 `aisWidth:"11"`
}
// DataLinkManagementMessage should be used by base station(s) to pre-announce the fixed allocation
// schedule (FATDMA) for one or more base station(s) and it should be repeated as often as required. This
// way the system can provide a high level of integrity for base station(s). This is especially important in
// regions where several base stations are located adjacent to each other and mobile station(s) move
// between these different regions. These reserved slots cannot be autonomously allocated by mobile
// stations.
type DataLinkManagementMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"160"`
Spare uint8 `aisWidth:"2" aisEncodeAs:"0"`
Data [4]DataLinkManagementMessageData `aisWidth:"0"`
}
// ChannelManagementBroadcastData contains the boundrary for a broadcasted channel mangement packet.
type ChannelManagementBroadcastData struct {
Longitude1 FieldLatLonCoarse `aisWidth:"18"`
Latitude1 FieldLatLonCoarse `aisWidth:"17"`
Longitude2 FieldLatLonCoarse `aisWidth:"18"`
Latitude2 FieldLatLonCoarse `aisWidth:"17"`
}
// ChannelManagementUnicastData contains the destination addresses for a unicast channel mangement packet.
type ChannelManagementUnicastData struct {
AddressStation1 uint32 `aisWidth:"30"`
Spare2 uint8 `aisWidth:"5" aisEncodeAs:"0"`
AddressStation2 uint32 `aisWidth:"30"`
Spare3 uint8 `aisWidth:"5" aisEncodeAs:"0"`
}
// ChannelManagement should be transmitted by a base station (as a broadcast message) to command the VHF
// data link parameters for the geographical area designated in this message and should be accompanied
// by a Message 4 transmission for evaluation of the message within 120 NM. The geographical area
// designated by this message should be as defined in § 4.1, Annex 2. Alternatively, this message may
// be used by a base station (as an addressed message) to command individual AIS mobile stations to
// adopt the specified VHF data link parameters. When interrogated and no channel management
// performed by the interrogated base station, the not available and/or international default settings
// should be transmitted (see § 4.1, Annex 2).
type ChannelManagement struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
Spare1 uint8 `aisWidth:"2" aisEncodeAs:"0"`
ChannelA uint16 `aisWidth:"12"`
ChannelB uint16 `aisWidth:"12"`
TxRxMode uint8 `aisWidth:"4"`
LowPower bool `aisWidth:"1"`
Area ChannelManagementBroadcastData `aisWidth:"70" aisDependsBit:"~139" aisDependsField:"~IsAddressed"`
Unicast ChannelManagementUnicastData `aisWidth:"70" aisDependsBit:"139" aisDependsField:"IsAddressed"`
IsAddressed bool `aisWidth:"1"`
BwA bool `aisWidth:"1"`
BwB bool `aisWidth:"1"`
TransitionalZoneSize uint8 `aisWidth:"3"`
Spare4 uint32 `aisWidth:"23" aisEncodeAs:"0"`
}
// SingleSlotBinaryMessage is primarily intended short infrequent data transmissions. The single slot
// binary message can contain up to 128 data-bits depending on the coding method used for the contents,
// and the destination indication of broadcast or addressed. The length should not exceed one slot. See
// application identifiers in § 2.1, Annex 5.
type SingleSlotBinaryMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"168"`
DestinationIDValid bool `aisWidth:"1"`
ApplicationIDValid bool `aisWidth:"1"`
DestinationID uint32 `aisWidth:"30" aisDependsBit:"38" aisDependsField:"DestinationIDValid"`
Spare uint8 `aisWidth:"2" aisDependsBit:"38" aisDependsField:"DestinationIDValid" aisEncodeAs:"0"`
ApplicationID FieldApplicationIdentifier `aisWidth:"16" aisDependsBit:"39" aisDependsField:"ApplicationIDValid"`
Payload []byte `aisWidth:"-1"`
}
// MultiSlotBinaryMessage is primarily intended for scheduled binary data transmissions by applying either
// the SOTDMA or ITDMA access scheme. This multiple slot binary message can contain up to 1 004 data-
// bits (using 5 slots) depending on the coding method used for the contents, and the destination
// indication of broadcast or addressed. See application identifiers in § 2.1, Annex 5.
type MultiSlotBinaryMessage struct {
Header `aisWidth:"38"`
Valid bool `aisEncodeMaxLen:"1064"`
DestinationIDValid bool `aisWidth:"1"`
ApplicationIDValid bool `aisWidth:"1"`
DestinationID uint32 `aisWidth:"30" aisDependsBit:"38" aisDependsField:"DestinationIDValid"`
Spare1 uint8 `aisWidth:"2" aisDependsBit:"38" aisDependsField:"DestinationIDValid" aisEncodeAs:"0"`
ApplicationID FieldApplicationIdentifier `aisWidth:"16" aisDependsBit:"39" aisDependsField:"ApplicationIDValid"`
Payload []byte `aisWidth:"-1"`
Spare2 uint8 `aisWidth:"4" aisEncodeAs:"0"`
CommunicationStateItdma `aisWidth:"20"`
}
// FieldETA represents the encoding of the estimated time of arrival
type FieldETA struct {
Month uint8 `aisWidth:"4"`
Day uint8 `aisWidth:"5"`
Hour uint8 `aisWidth:"5"`
Minute uint8 `aisWidth:"6"`
}
// FieldDimension represents the encoding of the dimension
type FieldDimension struct {
A uint16 `aisWidth:"9"`
B uint16 `aisWidth:"9"`
C uint8 `aisWidth:"6"`
D uint8 `aisWidth:"6"`
}
// FieldApplicationIdentifier represents the encoding of the application identifier
type FieldApplicationIdentifier struct {
Valid bool
DesignatedAreaCode uint16 `aisWidth:"10"`
FunctionIdentifier uint8 `aisWidth:"6"`
}
// HasCommunicationState indicates that a message contains commuication state
type HasCommunicationState interface {
IsItdma() int
GetState() uint32
}
// CommunicationStateItdma represents the encoding of the communication state if the
// ITDMA type is included in the message
type CommunicationStateItdma struct {
CommunicationStateIsItdma bool `aisWidth:"1"`
CommunicationState uint32 `aisWidth:"19"`
}
// IsItdma indicates if Itdma is used.
func (c CommunicationStateItdma) IsItdma() int {
if c.CommunicationStateIsItdma {
return 1
}
return 0
}
// GetState will return the communication state
func (c CommunicationStateItdma) GetState() uint32 {
return c.CommunicationState
}
// CommunicationStateNoItdma represents the encoding of the communication state if the
// type is fixed
type CommunicationStateNoItdma struct {
CommunicationState uint32 `aisWidth:"19"`
}
// IsItdma indicates if Itdma is used. Return -1 for unknown as it depends
// on the message
func (c CommunicationStateNoItdma) IsItdma() int {
return -1
}
// GetState will return the communication state
func (c CommunicationStateNoItdma) GetState() uint32 {
return c.CommunicationState
}
// Field10 represents an unsigned value multiplied by 10
type Field10 float64
// FieldLatLonCoarse represents a 1/10' position
type FieldLatLonCoarse float64
// FieldLatLonFine represents a 1/10000' position
type FieldLatLonFine float64
func init() {
msgMap[1].rType = reflect.TypeOf(PositionReport{})
msgMap[2].rType = reflect.TypeOf(PositionReport{})
msgMap[3].rType = reflect.TypeOf(PositionReport{})
msgMap[4].rType = reflect.TypeOf(BaseStationReport{})
msgMap[5].rType = reflect.TypeOf(ShipStaticData{})
msgMap[6].rType = reflect.TypeOf(AddressedBinaryMessage{})
msgMap[7].rType = reflect.TypeOf(BinaryAcknowledge{})
msgMap[8].rType = reflect.TypeOf(BinaryBroadcastMessage{})
msgMap[9].rType = reflect.TypeOf(StandardSearchAndRescueAircraftReport{})
msgMap[10].rType = reflect.TypeOf(CoordinatedUTCInquiry{})
msgMap[11].rType = reflect.TypeOf(BaseStationReport{})
msgMap[12].rType = reflect.TypeOf(AddessedSafetyMessage{})
msgMap[13].rType = reflect.TypeOf(BinaryAcknowledge{})
msgMap[14].rType = reflect.TypeOf(SafetyBroadcastMessage{})
msgMap[15].rType = reflect.TypeOf(Interrogation{})
msgMap[16].rType = reflect.TypeOf(AssignedModeCommand{})
msgMap[17].rType = reflect.TypeOf(GnssBroadcastBinaryMessage{})
msgMap[18].rType = reflect.TypeOf(StandardClassBPositionReport{})
msgMap[19].rType = reflect.TypeOf(ExtendedClassBPositionReport{})
msgMap[20].rType = reflect.TypeOf(DataLinkManagementMessage{})
msgMap[21].rType = reflect.TypeOf(AidsToNavigationReport{})
msgMap[22].rType = reflect.TypeOf(ChannelManagement{})
msgMap[23].rType = reflect.TypeOf(GroupAssignmentCommand{})
msgMap[24].rType = reflect.TypeOf(StaticDataReport{})
msgMap[25].rType = reflect.TypeOf(SingleSlotBinaryMessage{})
msgMap[26].rType = reflect.TypeOf(MultiSlotBinaryMessage{})
msgMap[27].rType = reflect.TypeOf(LongRangeAisBroadcastMessage{})
}
func encodeHelper(p Packet) Packet {
switch x := p.(type) {
case Interrogation:
if x.Station2.Valid && !x.Station1Msg2.Valid {
/* All values should be set to zero and the field must be encoded! */
x.Station1Msg2 = InterrogationStation1Message2{Valid: true}
}
return x
}
return p
}
func decodeHelper(p Packet) Packet {
switch x := p.(type) {
case Interrogation:
if x.Station2.Valid {
/* If Station1Msg2 is all zeros it actually is not valid */
if x.Station1Msg2.MessageID == 0 && x.Station1Msg2.SlotOffset == 0 {
x.Station1Msg2.Valid = false
}
}
return x
}
return p
}