Initial commit

#! /usr/bin/env python3

from bitstring import BitStream

import spiceypy as spice

class PacketId:

    def __init__(self,data):

        pID = BitStream(hex=data).unpack('uint: 3, 2*bin: 1, bits: 11')

        self.VersionNum = pID[0]

        self.packetType = pID[1]

        self.dataFieldHeaderFlag = pID[2]

        self.Apid = pID[3].uint

        self.Pid = pID[3][0:7].uint

        self.Pcat = pID[3][7:].uint

        pass

    def serialize(self):

        return [self.VersionNum, self.packetType, self.dataFieldHeaderFlag,

                self.Apid, self.Pid, self.Pcat]

class SeqControl:

    def __init__(self,data):

        sq = BitStream(hex=data).unpack('bin:2,uint:14')

        self.SegmentationFlag = sq[0]

        self.SSC = sq[1]

    def serialize(self):

        return [self.SegmentationFlag, self.SSC]

class SourcePacketHeader:

    def __init__(self,data):

        # Read the Source Packet Header(48 bits)

        # - Packet ID (16 bits)

        self.packetId = PacketId(data[0:4])

        # - Packet Sequence Control (16 bits)

        self.sequeceControl = SeqControl(data[4:8])

        """ 

        - Packet Length (16 bits)

        In the packet is stored Packet length is an unsigned word 

        expressing “Number of octects contained in Packet Data Field” minus 1.

        """

        self.packetLength = BitStream(hex=data[8:12]).unpack('uint:16')[0]+1

        # Based on BepiColombo SIMBIO-SYS

        # ref: BC-SIM-GAF-IC-002 pag. 48

    def serialize(self):

        return [*self.packetId.serialize(), *self.sequeceControl.serialize(), self.packetLength]

class DataFieldHeader:

    def __init__(self,data):

        # Read The Data Field Header (80 bit)

        dfhData = BitStream(hex=data).unpack('bin:1,uint:3,bin:4,3*uint:8,uint:1,uint:31,uint:16')

        self.pusVersion = dfhData[1]

        self.ServiceType = dfhData[3]

        self.ServiceSubType = dfhData[4]

        self.DestinationId = dfhData[5]

        self.Synchronization = dfhData[6]

        self.CorseTime = dfhData[7]

        self.FineTime = dfhData[8]

        self.SCET = "%s.%s" % (self.CorseTime, self.FineTime)

        if self.Synchronization == 0:

            self.UTCTime = self.scet2UTC()

        else:

            self.UTCTime = '1970-01-01T00:00:00.00000Z'

        pass

    def serialize(self):

        return [self.pusVersion, self.ServiceType, self.ServiceSubType,

                self.DestinationId, self.SCET, self.UTCTime]

    def scet2UTC(self):

        et = spice.scs2e(-121, "{}.{}".format(self.CorseTime, self.FineTime))

        ScTime = spice.et2utc(et, 'ISOC', 5)

        return ScTime+'Z'

class PackeDataField:

    def __init__(self,data):

        # Data Field Header

        self.DFHeader = DataFieldHeader(data[0:20])

        # Data

        self.Data = data[20:]

        pass  

class CCSDS:

    """ Reader for the CCSDS header """

    """     Main Class   """

    def __init__(self,data):

        # Source Packet Header

        self.SPH = SourcePacketHeader(data[0:12])

        # Packet Data Field

        self.PDF = PackeDataField(data[12:])

        self.Data=self.PDF.Data

        pass