space_packet_parser.generators.ccsds

Packet generator utilities for CCSDS packets.

The parsing begins with binary data representing CCSDS Packets. A user can then create a generator from the binary data reading from a filelike object or a socket. The ccsds_generator function yields CCSDSPacketBytes objects that are the raw binary data of a single CCSDS packet. The CCSDSPacketBytes class can be used to inspect the CCSDS header fields of the packet, but it does not have any parsed content from the data field. This generator is useful for debugging and passing off to other parsing functions.

Attributes

logger

Classes

SequenceFlags

Enumeration of the possible sequence flags in a CCSDS packet.

CCSDSPacketBytes

Binary (bytes) representation of a CCSDS packet.

CCSDSPacket

Packet representing parsed data items from CCSDS packet(s). DEPRECATED

Functions

create_ccsds_packet(→ CCSDSPacketBytes)

Create a binary CCSDS packet from input values.

ccsds_generator(...)

A generator that reads raw packet data from a filelike object or a socket.

Module Contents

space_packet_parser.generators.ccsds.logger
class space_packet_parser.generators.ccsds.SequenceFlags

Bases: enum.IntEnum

Enumeration of the possible sequence flags in a CCSDS packet.

CONTINUATION = 0
FIRST = 1
LAST = 2
UNSEGMENTED = 3
class space_packet_parser.generators.ccsds.CCSDSPacketBytes

Bases: bytes

Binary (bytes) representation of a CCSDS packet.

Methods to extract the header fields are added to the raw bytes object.

HEADER_LENGTH_BYTES = 6
__str__() → str

Return str(self).

property version_number: int

CCSDS Packet Version Number

property type: int

CCSDS Packet Type

0 = Telemetry Packet 1 = Telecommand Packet

property secondary_header_flag: int

CCSDS Secondary Header Flag

0 = No secondary header 1 = Secondary header present

property apid: int

CCSDS Application Process Identifier (APID)

property sequence_flags: int

CCSDS Packet Sequence Flags

00 = Continuation packet 01 = First packet 10 = Last packet 11 = Unsegmented packet (standalone)

property sequence_count: int

CCSDS Packet Sequence Count

property data_length: int

CCSDS Packet Data Length

Section 4.1.3.5.3 The length count C shall be expressed as: C = (Total Number of Octets in the Packet Data Field) - 1

property header_values: tuple[int, Ellipsis]

Convenience property for tuple of header values

property header: bytes

Convenience property returns the CCSDS header bytes

property user_data: bytes

Convenience property returns only the user data bytes (no header)

Notes:

This includes the secondary header, if present

space_packet_parser.generators.ccsds.create_ccsds_packet(data=b'\x00', *, version_number=0, type=0, secondary_header_flag=0, apid=2047, sequence_flags=SequenceFlags.UNSEGMENTED, sequence_count=0) → CCSDSPacketBytes

Create a binary CCSDS packet from input values.

Pack the header fields into the proper bit locations and append the data bytes.

Parameters:

  • data (bytes) – User data bytes (up to 65536 bytes)

  • version_number (int) – CCSDS Packet Version Number (3 bits)

  • type (int) – CCSDS Packet Type (1 bit)

  • secondary_header_flag (int) – CCSDS Secondary Header Flag (1 bit)

  • apid (int) – CCSDS Application Process Identifier (APID) (11 bits)

  • sequence_flags (int) – CCSDS Packet Sequence Flags (2 bits)

  • sequence_count (int) – CCSDS Packet Sequence Count (14 bits)

Returns:

Resulting binary packet

Return type:

CCSDSPacketBytes

Notes

This function is extremely useful for generating test packets for debugging or mocking purposes.

class space_packet_parser.generators.ccsds.CCSDSPacket(*args, **kwargs)

Bases: space_packet_parser.common.SpacePacket

Packet representing parsed data items from CCSDS packet(s). DEPRECATED

This class is deprecated and will be removed in a future release. Use the SpacePacket class instead. In an XTCE representation, there is no guarantee that the CCSDS packet header will be defined as individual elements. If you want to access those elements, you can use the CCSDSPacketBytes class to extract the header fields with specific methods.

Container that stores the raw packet data (bytes) as an instance attribute and the parsed data items in a dictionary interface. A CCSDSPacket generally begins as an empty dictionary that gets filled as the packet is parsed. The first 7 items in the dictionary make up the packet header (accessed with CCSDSPacket.header), and the rest of the items make up the user data (accessed with CCSDSPacket.user_data). To access the raw bytes of the packet, use the CCSDSPacket.binary_data attribute.

space_packet_parser.generators.ccsds.ccsds_generator(binary_data: BinaryIO | socket.socket | bytes, *, buffer_read_size_bytes: int | None = None, show_progress: bool = False, skip_header_bytes: int = 0, combine_segmented_packets: bool = False, secondary_header_bytes: int = 0) → collections.abc.Iterator[CCSDSPacketBytes]

A generator that reads raw packet data from a filelike object or a socket.

Each iteration of the generator yields a CCSDSPacketBytes object that makes up a single CCSDS packet. If combining segmented packets is enabled, the generator will combine segmented packets into a single packet for parsing. This is useful for parsing packets that are split into multiple packets due to size constraints.

Parameters:

  • binary_data (Union[BinaryIO, socket.socket, bytes]) – Binary data source containing CCSDSPackets.

  • buffer_read_size_bytes (int, optional) – Number of bytes to read from e.g. a BufferedReader or socket binary data source on each read attempt. If None, defaults to 4096 bytes from a socket, -1 (full read) from a file.

  • show_progress (bool) – Default False. If True, prints a status bar. Note that for socket sources, the percentage will be zero until the generator ends.

  • skip_header_bytes (int) – Default 0. The parser skips this many bytes at the beginning of every packet. This allows dynamic stripping of additional header data that may be prepended to packets in “raw record” file formats.

  • combine_segmented_packets (bool) – Default False. If True, combines segmented packets into a single packet for parsing. This is useful for parsing packets that are split into multiple packets due to size constraints. The packet data is combined by concatenating the data from each packet together. The combined packet is then parsed as a single packet. Only the first CCSDS header is kept when concatenating continued packets. CCSDS headers (and secondary headers) from continuation packets are discarded.

  • secondary_header_bytes (int) – Default 0. The length of the secondary header in bytes. This is used to skip the secondary header of segmented packets. The byte layout within the returned packet has all data concatenated together as follows: [packet0header, packet0secondaryheader, packet0data, packet1data, packet2data, …].

Yields:

CCSDSPacketBytes – The bytes of a single CCSDS packet.