Python struct.Struct() Examples

def send_dbman_msg(self, opcode, msg):
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.connect((self.target_ip, self.dbman_port))

        encodedMsg = encoder.encode(msg, defMode=True)
        msgLen = len(encodedMsg)
        values = (opcode, msgLen, encodedMsg)
        s = struct.Struct(">ii%ds" % msgLen)
        packed_data = s.pack(*values)

        sock.send(packed_data)

        res = sock.recv(1024)
        if res is not None:
            print "Received 10002 response..."
        sock.close() 

def go(fhs):
  fmt = None
  with open(opt_vocab, 'w') as vocab_out:
    with open(opt_output, 'w') as vecs_out:
      for lines in izip(*fhs):
        parts = [line.split() for line in lines]
        token = parts[0][0]
        if any(part[0] != token for part in parts[1:]):
          raise IOError('vector files must be aligned')

        print >> vocab_out, token

        vec = [sum(float(x) for x in xs) for xs in zip(*parts)[1:]]
        if not fmt:
          fmt = struct.Struct('%df' % len(vec))

        vecs_out.write(fmt.pack(*vec)) 

def parse(cls, buff, offset):
        """
        Given a buffer and offset, returns the parsed value and new offset.

        Parses the ``size_primitive`` first to determine how many more bytes to
        consume to extract the value.
        """
        size, offset = cls.size_primitive.parse(buff, offset)
        if size == -1:
            return None, offset

        var_struct = struct.Struct("!%ds" % size)

        value = var_struct.unpack_from(buff, offset)[0]
        value = cls.parse_value(value)
        offset += var_struct.size

        return value, offset 

def __init__(self):
        """
        A state machine that handles the functionality needed to create and transmit a message
        """
        # Constants
        self.MAX_PAYLOAD_LENGTH = 40  # TBD
        self.MAX_MSG_DATA_LENGTH = 38  # TDB
        # States
        self.STATE_IDLE = 0
        self.STATE_INIT = 1
        self.STATE_FRAGMENT = 2
        self.STATE_TX = 3
        # Frame Types
        self.MSG_START = 255
        self.MSG_DATA = 254
        self.MSG_END = 253
        # Variables
        self.list_packets = []
        # Frame Definitions
        self.pkt_datagram_frame = struct.Struct('1B 40s')  # Fixed
        self.pkt_start = struct.Struct('9s 3B')  # Fixed
        self.pkt_data = struct.Struct('2B 38s')  # Variable  Data Length
        self.pkt_end = struct.Struct('1B')  # Fixed 

def __init__(self):
        """
        The message application object contains all the functions, definitions, and state machines needed to implement
        a bare-bones text message application using the Faraday command application "experimental RF Packet Forward"
        functionality."
        """
        # Identification Variables
        self.local_device_callsign = 'kb1lqc'
        self.local_device_node_id = 1
        # Initialize objects
        self.faraday_Rx = faradaybasicproxyio.proxyio()
        self.faraday_Rx_SM = MsgStateMachineRx()
        # Initialize variables
        # Frame Definitions (Should be combined later with TX?)
        self.pkt_datagram_frame = struct.Struct('1B 41s')  # Fixed
        self.pkt_start = struct.Struct('9s 3B')  # Fixed
        self.pkt_data = struct.Struct('2B 39s')  # Variable  Data Length
        self.pkt_end = struct.Struct('1B')  # Fixed 

def __init__(self):
        """
        A state machine that handles the functionality needed to create and transmit a message
        """
        # Constants
        self.MAX_PAYLOAD_LENGTH = 40  # TBD
        self.MAX_MSG_DATA_LENGTH = 38  # TDB
        # States
        self.STATE_IDLE = 0
        self.STATE_INIT = 1
        self.STATE_FRAGMENT = 2
        self.STATE_TX = 3
        # Frame Types
        self.MSG_START = 255
        self.MSG_DATA = 254
        self.MSG_END = 253
        # Variables
        self.list_packets = []
        # Frame Definitions
        self.pkt_datagram_frame = struct.Struct('1B 40s')  # Fixed
        self.pkt_start = struct.Struct('9s 3B')  # Fixed
        self.pkt_data = struct.Struct('2B 38s')  # Variable  Data Length
        self.pkt_end = struct.Struct('1B')  # Fixed 

def __init__(self):
        """
        The message application object contains all the functions, definitions, and state machines needed to implement
        a bare-bones text message application using the Faraday command application "experimental RF Packet Forward"
        functionality."
        """
        # Identification Variables
        self.local_device_callsign = 'kb1lqc'
        self.local_device_node_id = 1
        # Initialize objects
        self.faraday_Rx = faradaybasicproxyio.proxyio()
        self.faraday_Rx_SM = MsgStateMachineRx()
        # Initialize variables
        # Frame Definitions (Should be combined later with TX?)
        self.pkt_datagram_frame = struct.Struct('1B 41s')  # Fixed
        self.pkt_start = struct.Struct('9s 3B')  # Fixed
        self.pkt_data = struct.Struct('2B 39s')  # Variable  Data Length
        self.pkt_end = struct.Struct('1B')  # Fixed 

def __init__(self):
        """
        A state machine that handles the functionality needed to create and transmit a message
        """
        # Constants
        self.MAX_PAYLOAD_LENGTH = 40  # TBD
        self.MAX_MSG_DATA_LENGTH = 38  # TDB
        # States
        self.STATE_IDLE = 0
        self.STATE_INIT = 1
        self.STATE_FRAGMENT = 2
        self.STATE_TX = 3
        # Frame Types
        self.MSG_START = 255
        self.MSG_DATA = 254
        self.MSG_END = 253
        # Variables
        self.list_packets = []
        # Frame Definitions
        self.pkt_datagram_frame = struct.Struct('1B 40s')  # Fixed
        self.pkt_start = struct.Struct('9s 3B')  # Fixed
        self.pkt_data = struct.Struct('2B 38s')  # Variable  Data Length
        self.pkt_end = struct.Struct('1B')  # Fixed 

def __init__(self):
        """
        A state machine that handles the functionality needed to create and transmit a message
        """
        #Constants
        self.MAX_PAYLOAD_LENGTH = 20  #TBD
        self.MAX_MSG_DATA_LENGTH = 18  #TDB
        #States
        self.STATE_IDLE = 0
        self.STATE_INIT = 1
        self.STATE_FRAGMENT = 2
        self.STATE_TX = 3
        #Frame Types
        self.MSG_START = 255
        self.MSG_DATA = 254
        self.MSG_END = 253
        #Variables
        self.list_packets = []
        #Frame Definitions
        self.pkt_datagram_frame = struct.Struct('1B 19s')
        self.pkt_start = struct.Struct('9s 3B')
        self.pkt_data = struct.Struct('2B 18s')
        self.pkt_end = struct.Struct('1B') 

def create_local_telem_update_packet():
    """
    A predefined command packet generator that provides a payload for the local telemetry update command.

    :Return: A completed packet

    .. todo:: This should be deprecated into a single "dummy" payload function
    """
    packet_struct = struct.Struct('>B')
    packet = packet_struct.pack(255)
    return packet


##############
## Command = Send RF Data Now
############## 

def create_rf_telem_update_packet():
    """
    A predefined command packet generator that provides a payload for the RF telemetry update command.

    :Return: A completed packet

    .. todo:: This should be deprecated into a single "dummy" payload function
    """
    packet_struct = struct.Struct('>B')
    packet = packet_struct.pack(255)
    return packet


##############
## Command = Update RF frequency
############## 

def create_update_rf_frequency_packet(frequency_mhz):
    """
    This function generates the command packet that updates the Faraday CC430 radio frequency.

    :param frequency_mhz: The frequency in MHz as an Integer or Float.

    :Return: A completed packet (string of bytes)

    """
    freq_list = create_freq_list(float(frequency_mhz))
    packet_struct = struct.Struct('3B')
    packet = packet_struct.pack(freq_list[0], freq_list[1], freq_list[2])
    return packet


##############
## Command = Change CC430 PATable Settings
## ucharPATable_Setting = Byte that is places into the PA Table
############## 

def create_update_rf_patable_packet(ucharPATable_Setting):
    """
    This function generates the command packet that updates the Faraday CC430 RF power setting.

    .. note:: A setting of 152 is the maximum output power, any number higher than 152 will be sent as a value of 152.

    :param ucharPATable_Setting: The RF power table register setting byte for the CC430.

    :Return: A completed packet (string of bytes)

    """
    packet_struct = struct.Struct('1B')
    packet = packet_struct.pack(ucharPATable_Setting)
    return packet


##############
## Command = RESET device debug Flash
## Note: Not payload packet needed, returing 1 byte of 0 just for placeholder
############## 

def CreatePacketMsgExperimental(msg_cmd, dest_callsign, dest_device_id, data_len, data):
    """
    This function creates the command packet expected by the command application routine that forwards a supplied payload over RF to a remote Faraday device. This is a very useful yet simple and un-optimized method of sending abritray data from one unit to another.

    :param dest_callsign: The callsign of the target Faraday unit
    :param dest_device_id: The device ID number of the target Faraday unit
    :param data_len: The length in bytes of the data payload supplied
    :param data: The data payload to be sent to the remote Faraday device over RF

    :Return: A completed packet (string of bytes)

    .. note: The data payload length cannot be larger than the maximum transmissible unit. Also, data only needs to be a string of bytes so both strings and packed binary data are acceptable.

    :Example: Creates an experiement message packet that sends "Testing" to the remote unit.

        >>> CreatePacketMsgExperimental(0, "KB1LQD", 1, 7, "Testing")


    """
    packet_struct = struct.Struct('1B9s2B42s')
    packet = packet_struct.pack(msg_cmd, str(dest_callsign).upper(), dest_device_id, data_len, data)
    return packet 

def __init__(self, input_channel, serial_physical_obj):
        #Initialize class variables
        self.rx_packet_queue = Queue.Queue()
        self.rx_data_payload_queue = Queue.Queue()
        self.logic_startbyte_received = False
        self.logic_escapebyte_received = False
        self.logic_stopbyte_received = False
        self.receiver_class = Receiver_Datalink_Device_State_Parser_Class(input_channel, serial_physical_obj)
        self.enable_flag = True
        self.max_payload_size = 6
        self.datalink_packet_format = 'c' + str(self.max_payload_size) + 'c' + 'c'
        self.reconstruct_data = ''
        self.timer_interval = 5
        self.timer = threading.Timer(self.timer_interval, self.timer_trip)
        self.datalink_packet_struct = struct.Struct('BBB125s')

        #Start
        threading.Thread.__init__(self)
        self.start()  #Starts the run() function and thread 

def __init__(self):
        """
        A state machine that handles the functionality needed to create and transmit a message
        """
        # Constants
        self.MAX_PAYLOAD_LENGTH = 40  # TBD
        self.MAX_MSG_DATA_LENGTH = 38  # TDB
        # States
        self.STATE_IDLE = 0
        self.STATE_INIT = 1
        self.STATE_FRAGMENT = 2
        self.STATE_TX = 3
        # Frame Types
        self.MSG_START = 255
        self.MSG_DATA = 254
        self.MSG_END = 253
        # Variables
        self.list_packets = []
        # Frame Definitions
        self.pkt_datagram_frame = struct.Struct('1B 40s')  # Fixed
        self.pkt_start = struct.Struct('9s 3B')  # Fixed
        self.pkt_data = struct.Struct('2B 38s')  # Variable  Data Length
        self.pkt_end = struct.Struct('1B')  # Fixed 

def __init__(self):
        """
        The message application object contains all the functions, definitions, and state machines needed to implement
        a bare-bones text message application using the Faraday command application "experimental RF Packet Forward"
        functionality."
        """
        # Identification Variables
        self.local_device_callsign = 'kb1lqc'
        self.local_device_node_id = 1
        # Initialize objects
        self.faraday_Rx = faradaybasicproxyio.proxyio()
        self.faraday_Rx_SM = MsgStateMachineRx()
        # Initialize variables
        # Frame Definitions (Should be combined later with TX?)
        self.pkt_datagram_frame = struct.Struct('1B 41s')  # Fixed
        self.pkt_start = struct.Struct('9s 3B')  # Fixed
        self.pkt_data = struct.Struct('2B 39s')  # Variable  Data Length
        self.pkt_end = struct.Struct('1B')  # Fixed 

def __init__(self, base, config, layered = False, **kwargs):
        addrspace.BaseAddressSpace.__init__(self, base, config, **kwargs)
        self.as_assert(base == None or layered, 'Must be first Address Space')
        self.as_assert(config.LOCATION.startswith("file://"), 'Location is not of file scheme')

        path = urllib.url2pathname(config.LOCATION[7:])
        self.as_assert(os.path.exists(path), 'Filename must be specified and exist')
        self.name = os.path.abspath(path)
        self.fname = self.name
        self.mode = 'rb'
        if config.WRITE:
            self.mode += '+'
        self.fhandle = open(self.fname, self.mode)
        self.fhandle.seek(0, 2)
        self.fsize = self.fhandle.tell()
        self._long_struct = struct.Struct("=I")

    # Abstract Classes cannot register options, and since this checks config.WRITE in __init__, we define the option here 

def push_vm_param(self, param):
        if isinstance(param, bytearray) or isinstance(param, bytes):
            self.push_bytearray(param)
        elif isinstance(param, str):
            self.push_bytearray(bytes(param.encode()))
        elif isinstance(param, bool):
            self.push_bool(param)
        elif isinstance(param, int):
            self.push_int(param)
        elif isinstance(param, dict):
            self.push_map(param)
        elif isinstance(param, list):
            self.create_code_params_script_builder(param)
            self.push_int(len(param))
            self.emit(PACK)
        elif isinstance(param, Struct):
            self.push_struct(param)
        elif isinstance(param, Address):
            self.push_bytearray(param.to_bytes())
        elif isinstance(param, Account):
            self.push_bytearray(param.get_address().to_bytes())
        else:
            raise SDKException(ErrorCode.other_error('parameter type is error')) 

def _85encode(b, chars, chars2, pad=False, foldnuls=False, foldspaces=False):
    # Helper function for a85encode and b85encode
    if not isinstance(b, bytes_types):
        b = memoryview(b).tobytes()

    padding = (-len(b)) % 4
    if padding:
        b = b + b'\0' * padding
    words = struct.Struct('!%dI' % (len(b) // 4)).unpack(b)

    chunks = [b'z' if foldnuls and not word else
              b'y' if foldspaces and word == 0x20202020 else
              (chars2[word // 614125] +
               chars2[word // 85 % 7225] +
               chars[word % 85])
              for word in words]

    if padding and not pad:
        if chunks[-1] == b'z':
            chunks[-1] = chars[0] * 5
        chunks[-1] = chunks[-1][:-padding]

    return b''.join(chunks) 

def get_option_flags(option_num):
        """
        Get Critical, UnSafe, NoCacheKey flags from the option number
        as per RFC 7252, section 5.4.6

        :param option_num: option number
        :return: option flags
        :rtype: 3-tuple (critical, unsafe, no-cache)
        """
        opt_bytes = array.array('B', '\0\0')
        if option_num < 256:
            s = struct.Struct("!B")
            s.pack_into(opt_bytes, 0, option_num)
        else:
            s = struct.Struct("H")
            s.pack_into(opt_bytes, 0, option_num)
        critical = (opt_bytes[0] & 0x01) > 0
        unsafe = (opt_bytes[0] & 0x02) > 0
        nocache = ((opt_bytes[0] & 0x1e) == 0x1c)
        return (critical, unsafe, nocache) 

def read_option_value_from_nibble(nibble, pos, values):
        """
        Calculates the value used in the extended option fields.

        :param nibble: the 4-bit option header value.
        :return: the value calculated from the nibble and the extended option value.
        """
        if nibble <= 12:
            return nibble, pos
        elif nibble == 13:
            tmp = struct.unpack("!B", values[pos].to_bytes(1, "big"))[0] + 13
            pos += 1
            return tmp, pos
        elif nibble == 14:
            s = struct.Struct("!H")
            tmp = s.unpack_from(values[pos:].to_bytes(2, "big"))[0] + 269
            pos += 2
            return tmp, pos
        else:
            raise AttributeError("Unsupported option nibble " + str(nibble)) 

def go(fhs):
  fmt = None
  with open(opt_vocab, 'w') as vocab_out:
    with open(opt_output, 'w') as vecs_out:
      for lines in izip(*fhs):
        parts = [line.split() for line in lines]
        token = parts[0][0]
        if any(part[0] != token for part in parts[1:]):
          raise IOError('vector files must be aligned')

        print >> vocab_out, token

        vec = [sum(float(x) for x in xs) for xs in zip(*parts)[1:]]
        if not fmt:
          fmt = struct.Struct('%df' % len(vec))

        vecs_out.write(fmt.pack(*vec)) 

def unpack(self, fmt):
        ''' Unpack values from contained buffer

        Unpacks values from ``self.buf`` and updates ``self.ptr`` to the
        position after the read data.

        Parameters
        ----------
        fmt : str
           format string as for ``unpack``

        Returns
        -------
        values : tuple
           values as unpacked from ``self.buf`` according to `fmt`
        '''
        # try and get a struct corresponding to the format string from
        # the cache
        pkst = self._cache.get(fmt)
        if pkst is None: # struct not in cache
            # if we've not got a default endian, or the format has an
            # explicit endianness, then we make a new struct directly
            # from the format string
            if self.endian is None or fmt[0] in _ENDIAN_CODES:
                pkst = Struct(fmt)
            else: # we're going to modify the endianness with our
                # default. 
                endian_fmt = self.endian + fmt
                pkst = Struct(endian_fmt)
                # add an entry in the cache for the modified format
                # string as well as (below) the unmodified format
                # string, in case we get a format string with the same
                # endianness as default, but specified explicitly.
                self._cache[endian_fmt] = pkst
            self._cache[fmt] = pkst
        values = pkst.unpack_from(self.buf, self.ptr)
        self.ptr += pkst.size
        return values 

def _to_byte_string(value, num_bits):
    """Convert an integer to a big-endian string of bytes with padding.

    Padding is added at the end (i.e. after the least-significant bit) if
    required.
    """

    shifts = range(num_bits - 8, -8, -8)
    byte_at = lambda off: (  # noqa: E731
        (value >> off if off >= 0 else value << -off) & 0xff)
    return ''.join(struct.Struct(">B").pack(byte_at(offset))
                   for offset in shifts) 

def read_struct(self, fmt):
        s = struct.Struct(fmt)
        result = s.unpack_from(self._data, self._position)
        self._position += s.size
        return result 

def _GenerateRequestLogId():
  """Generates the request log id for the current request."""
  sec = int(_request_time)
  usec = int(1000000 * (_request_time - sec))
  h = hashlib.sha1(str(_request_id)).digest()[:4]
  packed = struct.Struct('> L L').pack(sec, usec)
  return binascii.b2a_hex(packed + h) 

def make_header_packer(header_format_class, endian='>'):
    cformat, field_name_allocations = compile_struct(
        header_format_class,
        getattr(header_format_class, 'START_OFFSET_IN_BYTES', 0),
        getattr(header_format_class, 'LENGTH_IN_BYTES', None),
        endian)
    structure = Struct(cformat)

    one_to_one = all(len(fields) == 1 for fields in field_name_allocations)

    if one_to_one:
        return BijectiveHeaderPacker(header_format_class, structure, field_name_allocations)
    return SurjectiveHeaderPacker(header_format_class, structure, field_name_allocations) 

def __setstate__(self, state):
        if state['__version__'] != __version__:
            raise TypeError("Cannot unpickle {} version {} into version {}"
                            .format(self.__class__.__name__,
                                    state['__version__'],
                                    __version__))
        del state['__version__']

        structure = Struct(state['_structure_format'])
        state['_structure'] = structure
        del state['_structure_format']
        self.__dict__.update(state) 

def parse(cls, buff, offset):
        """
        Given a buffer and offset, returns the parsed value and new offset.

        Uses the ``format`` class attribute to unpack the data from the buffer
        and determine the used up number of bytes.
        """
        primitive_struct = struct.Struct("!" + cls.fmt)

        value = primitive_struct.unpack_from(buff, offset)[0]
        offset += primitive_struct.size

        return value, offset