def header(self, value):
#self._header need to contain header class instance
if (type(value) == type(Header())):
self._header = value
else:
raise Exception(
'Invalid Header : object is not an instance of Header class')
def __getattr__(self, name):
if (name in self._names):
return self.TypeItem(self._values[self._names.index(name)],
self._p_values[self._names.index(name)],
self._m_classes[self._names.index(name)])
else:
raise Exception('Message Type {0} not defined'.format(name))
def destination(self, destination):
if (not isinstance(destination, int) or destination < 0
or destination > 255):
raise Exception('Invalid header destination set value: {0}'.format(
destination))
else:
self._destination = destination
def __getattr__(self, name):
if (name in self._names):
return self.DestinationItem(
self._values[self._names.index(name)],
self._p_values[self._names.index(name)])
else:
raise Exception('Message Destination {0} not defined'.format(name))
def __getattr__(cls, name):
if (name in cls._clist):
return cls._clist.index(name)
elif (name.endswith('_P')):
return pack(_PACK_FORMAT, cls.__getattr__(name[:-2]))
else:
raise Exception('MSG_PLUG_TYPE {0} not existing'.format(name))
def data(self, value):
if (self._header == None):
raise Exception(
'Invalid Header : header has to be define ahead of data')
else:
#self._data need to contain data class instance
#header type must match data type
self.header.type = TYPE.get_value_from_class(type(value))
self._data = value
def header(self):
if (self._header == None):
raise Exception('Invalid Header : header not define')
else:
return self._header
def data(self):
if (self._data == None):
raise Exception('Invalid Data : data not define')
else:
return self._data
def timestamp(self, timestamp):
if (timestamp < 0):
raise Exception(
'Invalid header timestamp set value: {0}'.format(timestamp))
else:
self._timestamp = timestamp
def timestamp(self):
if (self._timestamp == None):
raise Exception('Invalid header data : timestamp not define')
else:
return self._timestamp
def type(self):
if (self._type == None):
raise Exception('Invalid header data : type not define')
else:
return self._type
def source(self, source):
if (not isinstance(source, int) or source < 0 or source > 255):
raise Exception(
'Invalid header source set value: {0}'.format(source))
else:
self._source = source
def source(self):
if (self._source == None):
raise Exception('Invalid header data : source not define')
else:
return self._source
def destination(self):
if (self._destination == None):
raise Exception('Invalid header data : destination not define')
else:
return self._destination
def _get_X_from_Y(self, value, X_table, Y_table):
if (value in Y_table):
return X_table[Y_table.index(value)]
else:
raise Exception(
'Message Type search item not defined'.format(value))
def value(self):
if (self._value == None):
raise Exception('Invalid value : value not define')
else:
return self._value
def type(self, type):
if (not type in TYPE.values):
raise Exception('Invalid header type set value: {0}'.format(type))
else:
self._type = type
def _decode(self, msgbuf):
'''
Decode a buffer as a MAVLink message
'''
try:
magic, mlen, seq, srcSystem, srcComponent, msgId = struct.unpack(
'cBBBBB', msgbuf[:6])
except struct.error as emsg:
raise Exception('Unable to unpack MAVLink header: %s' % emsg)
if ord(magic) != 254:
raise Exception("invalid MAVLink prefix '%s'" % magic)
if mlen != len(msgbuf) - 8:
raise Exception(
'invalid MAVLink message length. Got %u expected %u, msgId=%u'
% (len(msgbuf) - 8, mlen, msgId))
if not msgId in mavlink.mavlink_map:
raise Exception('unknown MAVLink message ID %u' % msgId)
# decode the payload
type = mavlink.mavlink_map[msgId]
fmt = type.format
order_map = type.orders
len_map = type.lengths
crc_extra = type.crc_extra
# decode the checksum
try:
crc, = struct.unpack('<H', msgbuf[-2:])
except struct.error as emsg:
raise Exception('Unable to unpack MAVLink CRC: %s' % emsg)
crcbuf = msgbuf[1:-2]
crcbuf = crcbuf + struct.pack('B', crc_extra)
crc2 = x25crc(crcbuf)
if crc != crc2.crc:
raise Exception(
'invalid MAVLink CRC in msgID %u 0x%04x should be 0x%04x' %
(msgId, crc, crc2.crc))
try:
t = struct.unpack(fmt, msgbuf[6:-2])
except struct.error as emsg:
raise Exception(
'Unable to unpack MAVLink payload type=%s fmt=%s payloadLength=%u: %s'
% (type, fmt, len(msgbuf[6:-2]), emsg))
tlist = list(t)
# handle sorted fields
if True:
t = tlist[:]
if sum(len_map) == len(len_map):
# message has no arrays in it
for i in range(0, len(tlist)):
tlist[i] = t[order_map[i]]
else:
# message has some arrays
tlist = []
for i in range(0, len(order_map)):
order = order_map[i]
L = len_map[order]
tip = sum(len_map[:order])
field = t[tip]
if L == 1 or isinstance(field, str):
tlist.append(field)
else:
tlist.append(t[tip:(tip + L)])
# terminate any strings
for i in range(0, len(tlist)):
if isinstance(tlist[i], str):
tlist[i] = str(mavlink.MAVString(tlist[i]))
t = tuple(tlist)
# construct the message object
try:
m = type(*t)
except Exception as emsg:
raise Exception(
'Unable to instantiate MAVLink message of type %s : %s' %
(type, emsg))
m._msgbuf = msgbuf
m._payload = msgbuf[6:-2]
m._crc = crc
m._header = mavlink.MAVLink_header(msgId, mlen, seq, srcSystem,
srcComponent)
self._value = m
return m