fsfw/tmtcpacket/SpacePacket.h

71 lines
2.7 KiB
C++

#ifndef SPACEPACKET_H_
#define SPACEPACKET_H_
#include "../tmtcpacket/SpacePacketBase.h"
/**
* The SpacePacket class is a representation of a simple CCSDS Space Packet
* without (control over) a secondary header.
* It can be instantiated with a size smaller than \c PACKET_MAX_SIZE. Its
* main use is to serve as an idle packet in case no other packets are sent.
* For the ECSS PUS part the TcPacket and TmPacket classes are used.
* A pointer to \c local_data is passed to the \c SpacePacketBase parent class,
* so the parent's methods are reachable.
* @ingroup tmtcpackets
*/
class SpacePacket: public SpacePacketBase {
public:
static const uint16_t PACKET_MAX_SIZE = 1024;
/**
* The constructor initializes the packet and sets all header information
* according to the passed parameters.
* @param packetDataLength Sets the packet data length field and therefore specifies the size of the packet.
* @param isTelecommand Sets the packet type field to either TC (true) or TM (false).
* @param apid Sets the packet's APID field. The default value describes an idle packet.
* @param sequenceCount ets the packet's Source Sequence Count field.
*/
SpacePacket(uint16_t packetDataLength, bool isTelecommand = false,
uint16_t apid = APID_IDLE_PACKET, uint16_t sequenceCount = 0);
/**
* The class's default destructor.
*/
virtual ~SpacePacket();
/**
* With this call, the complete data content (including the CCSDS Primary
* Header) is overwritten with the byte stream given.
* @param p_data Pointer to data to overwrite the content with
* @param packet_size Size of the data
* @return @li \c true if packet_size is smaller than \c MAX_PACKET_SIZE.
* @li \c false else.
*/
bool addWholeData(const uint8_t* p_data, uint32_t packet_size);
protected:
/**
* This structure defines the data structure of a Space Packet as local data.
* There's a buffer which corresponds to the Space Packet Data Field with a
* maximum size of \c PACKET_MAX_SIZE.
*/
struct PacketStructured {
CCSDSPrimaryHeader header;
uint8_t buffer[PACKET_MAX_SIZE];
};
/**
* This union simplifies accessing the full data content of the Space Packet.
* This is achieved by putting the \c PacketStructured struct in a union with
* a plain buffer.
*/
union SpacePacketData {
PacketStructured fields;
uint8_t byteStream[PACKET_MAX_SIZE + sizeof(CCSDSPrimaryHeader)];
};
/**
* This is the data representation of the class.
* It is a struct of CCSDS Primary Header and a data field, which again is
* packed in an union, so the data can be accessed as a byte stream without
* a cast.
*/
SpacePacketData localData;
};
#endif /* SPACEPACKET_H_ */