def GetKDPPacketHeaderInt(request=0, is_reply=False, seq=0, length=0, key=0):
    """ create a 64 bit number that could be saved as pkt_hdr_t
        params:
            request:int   - 7 bit kdp_req_t request type
            is_reply:bool - False => request, True => reply 
            seq: int      - 8  sequence number within session 
            length: int   - 16 bit length of entire pkt including hdr 
            key: int      - session key 
        returns:
            int - 64 bit number to be saved in memory
    """
    retval = request 
    if is_reply:
        retval = 1<<7 |retval
    retval = (seq << 8) | retval
    retval = (length << 16) | retval
    #retval = (retval << 32) | key
    retval = (key << 32) | retval
    return retval