def test_pull_rx_message_corrupted():
""" Should not receive a corrupted message """
port = MockSerialPort()
frame = Frame(port)
# this is the serial representation of framed data, with checksum
port.serial_data_in = [
frame.SOF, 1, 2, frame.ESC, frame.SOF ^ frame.ESC_XOR, 4, frame.ESC,
frame.EOF ^ frame.ESC_XOR, 6, frame.ESC, frame.ESC ^ frame.ESC_XOR, 8,
9, 10, 148, 21, frame.EOF
]
time.sleep(0.1)
assert frame.pull_rx_message() == []
def test_pull_rx_message():
""" Test the retrieval of a message """
port = MockSerialPort()
frame = Frame(port)
# this is the serial representation of framed data, with checksum
port.serial_data_in = [
frame.SOF, 1, 2, frame.ESC, frame.SOF ^ frame.ESC_XOR, 4, frame.ESC,
frame.EOF ^ frame.ESC_XOR, 6, frame.ESC, frame.ESC ^ frame.ESC_XOR, 8,
9, 10, 148, 20, frame.EOF
]
time.sleep(0.1)
# this is the expected 'de-framed' data
data_to_receive = [1, 2, frame.SOF, 4, frame.EOF, 6, frame.ESC, 8, 9, 10]
assert frame.pull_rx_message() == data_to_receive
class SerialDispatch(object):
""" Sends and receives blocks of data through a byte-aligned interface """
format_specifiers = {
0: 'NONE',
1: 'STRING',
2: 'U8',
3: 'S8',
4: 'U16',
5: 'S16',
6: 'U32',
7: 'S32',
8: 'FLOAT'
}
topical_data = {}
subscribers = {}
def __init__(self, serial_port, timeout=0.0):
""" Initializes frame and threading """
self.timeout = timeout
if serial_port:
self.frame = Frame(serial_port)
self.run_thread = True
self.thread = threading.Thread(target=self.run, args=())
self.thread.daemon = True
self.thread.start()
else:
print("Serial port not provided")
def close(self):
self.run_thread = False
def subscribe(self, topic, callback):
""" Adds a callback method to a topic
Args:
topic: a string representing the topic which is being subscribed to
callback: a function which is to be called when the topic is received
"""
try:
self.subscribers[topic].append(callback)
except:
self.subscribers[topic] = [callback]
def unsubscribe(self, topic, callback):
""" Removes the callback from the specified topic
Args:
topic: a string representing the topic which is being unsubscribed from
callback: a function which is being removed from the subscribed topic
"""
if self.subscribers[topic]:
self.subscribers[topic].remove(callback)
if len(self.subscribers[topic]) == 0:
self.subscribers.pop(topic)
def get_data(self, topic):
""" Provides a method to receive the data relevant to a topic
Args:
topic: the topic string
Returns:
The data relating to a particular topic as a list of lists
"""
return self.topical_data[topic]
def publish(self, topic, data, format_specifier=['STRING']):
""" Publishes data to a particular topic
Args:
topic: the topic to which to publish
format_specifier: a list of format specifiers
data: a list of lists, each internal list
containing a complete set of data
"""
# reverse the format specifier dictionary for convenience in this function
format_specifiers = {}
for key in self.format_specifiers.keys():
value = self.format_specifiers[key]
format_specifiers[value] = key
if format_specifier == ['STRING']:
length = len(data[0][0])
else:
length = len(data[0])
dim = len(data)
print(length)
msg = []
# create the header
topic_bytes = bytearray(topic, 'utf-8')
for e in topic_bytes:
msg.append(e)
msg.append(0) # null string terminator
msg.append(dim)
msg.append(length & 255)
msg.append((length & 65280) >> 8)
for i, e in enumerate(format_specifier):
fs = format_specifiers[e]
if (i & 1) == 0:
msg.append(fs & 15)
else:
msg[-1] += ((fs & 15) << 4)
for i, e in enumerate(format_specifier):
if e == 'NONE' or e == 'STRING':
str_array = bytearray(data[0][0], 'utf-8')
for e in str_array:
msg.append(e)
elif e == 'U8' or e == 'S8':
unsigned_data8 = [x if x > 0 else x + 256 for x in data[i]]
msg.extend(unsigned_data8)
elif e == 'U16' or e == 'S16':
unsigned_data16 = [x if x > 0 else x + 65536 for x in data[i]]
for x in unsigned_data16:
msg.append(x & 255)
msg.append((x & 65280) >> 8)
elif e == 'U32' or e == 'S32':
unsigned_data32 = [
x if x > 0 else x + 4294967296 for x in data[i]
]
for x in unsigned_data32:
msg.append(x & 255)
msg.append((x & 65280) >> 8)
msg.append((x & 16711680) >> 16)
msg.append((x & 4278190080) >> 24)
else:
print('width not supported')
msg_to_send = copy.deepcopy(msg)
self.frame.push_tx_message(msg_to_send)
return msg
def run(self):
""" Monitors received data and properly formats it """
while self.run_thread:
while self.frame.rx_is_available():
msg = self.frame.pull_rx_message()
# find the first '0' in the msg
zero_index = 0
for i, element in enumerate(msg):
if element == 0:
zero_index = i
break
topic = ''.join(chr(c) for c in msg[0:zero_index])
msg = msg[zero_index + 1:]
dim = msg.pop(0)
length = msg.pop(0)
length += msg.pop(0) * 256
# pull off the format specifiers
format_specifiers = []
i = 0
while True:
fs0 = msg.pop(0)
format_specifiers.append(self.format_specifiers[fs0 & 15])
i += 1
if i == dim:
break
format_specifiers.append(
self.format_specifiers[(fs0 & 240) >> 4])
i += 1
if i == dim:
break
for element in format_specifiers:
if element == 'STRING':
string_message = ''.join(chr(c) for c in msg)
self.topical_data[topic] = string_message
elif element == 'U8':
if not self.topical_data:
self.topical_data[topic] = []
# pull the next row of U8 from the msg
self.topical_data[topic].append(msg[0:length])
msg = msg[length:]
elif element == 'S8':
if not self.topical_data:
self.topical_data[topic] = []
# pull the next row of U8 from the msg
row = msg[0:length]
# apply the sign to each row
row = [(e - 256) if e > 127 else e for e in row]
self.topical_data[topic].append(row)
msg = msg[length:]
elif element == 'U16':
if not self.topical_data:
self.topical_data[topic] = []
# pull the next row of U16 from the msg
row8 = msg[0:length * 2]
row16 = []
while row8:
num16 = row8.pop(0)
num16 += row8.pop(0) * 256
row16.append(num16)
self.topical_data[topic].append(row16)
msg = msg[length * 2:]
elif element == 'S16':
if not self.topical_data:
self.topical_data[topic] = []
# pull the next row of U16 from the msg
row8 = msg[0:length * 2]
row16 = []
while row8:
num16 = row8.pop(0)
num16 += row8.pop(0) * 256
row16.append(num16)
# apply the sign to each row
row16 = [(e - 65536) if e > 32767 else e
for e in row16]
self.topical_data[topic].append(row16)
msg = msg[length * 2:]
elif element == 'U32':
if not self.topical_data:
self.topical_data[topic] = []
# pull the next row of U16 from the msg
row8 = msg[0:length * 4]
row32 = []
while row8:
num32 = row8.pop(0)
num32 += row8.pop(0) * 256
num32 += row8.pop(0) * 65536
num32 += row8.pop(0) * 16777216
row32.append(num32)
self.topical_data[topic].append(row32)
msg = msg[length * 4:]
elif element == 'S32':
if not self.topical_data:
self.topical_data[topic] = []
# pull the next row of U16 from the msg
row8 = msg[0:length * 4]
row32 = []
while row8:
num32 = row8.pop(0)
num32 += row8.pop(0) * 256
num32 += row8.pop(0) * 65536
num32 += row8.pop(0) * 16777216
row32.append(num32)
# apply the sign to each row
row32 = [(e - 4294967296) if e > 2147483648 else e
for e in row32]
self.topical_data[topic].append(row32)
msg = msg[length * 4:]
elif element == 'FLOAT':
pass
else:
print('unrecognized message type: ', element)
# remove any data that doesn't have subscribers
temp_dict = copy.deepcopy(self.topical_data)
keys = temp_dict.keys()
for key in keys:
if key not in self.subscribers:
self.topical_data.pop(key)
else:
# execute callbacks
for element in self.subscribers[key]:
element()
''' at this point, the data should have
been consumed by the function and can
now be discarded, which helps keep memory
use low'''
self.topical_data.pop(key)
if self.timeout:
time.sleep(self.timeout)