emane/ota/otamessage.py

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#
# Copyright (c) 2014,2017 - Adjacent Link LLC, Bridgewater, New Jersey
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from . import otaheader_pb2
from . import commonphyheader_pb2
import uuid
import struct

class OTAMessage:
    def __init__(self,
                 source,
                 destination,
                 registrationId,
                 subId,
                 bandwidthHz,
                 transmitters,
                 segments,
                 fixedAntennaGain = None):

        self._sequence = 0
        self._otaHeader = otaheader_pb2.OTAHeader()
        self._otaHeader.source = source
        self._otaHeader.destination = destination
        self._otaHeader.payloadInfo.eventLength = 0
        self._otaHeader.payloadInfo.controlLength = 2
        self._otaHeader.payloadInfo.dataLength = 0

        self._phyHeader = commonphyheader_pb2.CommonPHYHeader()
        self._phyHeader.registrationId = registrationId;
        self._phyHeader.subId = subId;
        self._phyHeader.bandwidthHz = bandwidthHz;

        if fixedAntennaGain is not None:
            self._phyHeader.fixedAntennaGain = fixedAntennaGain

        for nemId,powerdBm in transmitters:
            transmitter = self._phyHeader.transmitters.add()
            transmitter.nemId = nemId
            transmitter.powerdBm = powerdBm

        for frequencyHz, offsetMicroseconds, durationMicroseconds in segments:
            segment = self._phyHeader.frequencySegments.add()
            segment.frequencyHz = frequencyHz
            segment.offsetMicroseconds = offsetMicroseconds
            segment.durationMicroseconds = durationMicroseconds

    def generate(self,txTimeMicroseconds,sequence,uuid):
        self._otaHeader.uuid = uuid.bytes
        self._otaHeader.sequence = sequence
        self._phyHeader.sequenceNumber = self._sequence;
        self._sequence += 1
        self._phyHeader.txTimeMicroseconds = txTimeMicroseconds;

        phyHeader = self._phyHeader.SerializeToString()

        self._otaHeader.payloadInfo.dataLength = len(phyHeader) + 2;

        otaHeader = self._otaHeader.SerializeToString()

        return "".join((struct.pack("!H",len(otaHeader)),
                        otaHeader,
                        # PartInfo: no more parts, offset 0, size
                        struct.pack("!BII",
                                    0,
                                    0,
                                    self._otaHeader.payloadInfo.dataLength +
                                    self._otaHeader.payloadInfo.controlLength +
                                    self._otaHeader.payloadInfo.eventLength),
                        struct.pack("!H",0),
                        struct.pack("!H",len(phyHeader)),
                        phyHeader))