Replace to_byte operations with pack and unpack for Python 2.x

boris-wenzlaff · boris-wenzlaff · commit dd0312dc33bf · 2017-09-07T23:14:45.000+02:00
diff --git a/can/interfaces/serial/serial_can.py b/can/interfaces/serial/serial_can.py
@@ -8,6 +8,7 @@
 """
 
 import logging
+import struct
 
 logger = logging.getLogger('can.serial')
 
@@ -77,9 +78,16 @@ def send(self, msg, timeout=None):
         """
         if isinstance(msg.timestamp, float):
             msg.timestamp = int(msg.timestamp)
-        timestamp = msg.timestamp.to_bytes(4, byteorder='little')
-        a_id = msg.arbitration_id.to_bytes(4, byteorder='little')
-        dlc = msg.dlc.to_bytes(1, byteorder='little')
+        try:
+            timestamp = struct.pack('<I', msg.timestamp)
+        except Exception:
+            raise ValueError('Timestamp is out of range')
+        try:
+            a_id = struct.pack('<I', msg.arbitration_id)
+        except Exception:
+            raise ValueError('Arbitration Id is out of range')
+        # dlc = msg.dlc.to_bytes(1, byteorder='little')
+        dlc = struct.pack('<B', msg.dlc)
         byte_msg = bytes([0xAA]) + timestamp + dlc + a_id + msg.data + \
                    bytes([0xBB])
         self.ser.write(byte_msg)
@@ -110,11 +118,11 @@ def recv(self, timeout=None):
 
         if len(rx_byte) and ord(rx_byte) == 0xAA:
             s = bytearray(self.ser.read(4))
-            timestamp = int.from_bytes(s, byteorder='little', signed=False)
+            timestamp = (struct.unpack('<I', s))[0]
             dlc = ord(self.ser.read())
 
             s = bytearray(self.ser.read(4))
-            arb_id = int.from_bytes(s, byteorder='little', signed=False)
+            arb_id = (struct.unpack('<I', s))[0]
 
             data = self.ser.read(dlc)
 
diff --git a/test/serial_test.py b/test/serial_test.py
@@ -125,10 +125,10 @@ def test_rx_tx_max_timestamp(self):
 
     def test_rx_tx_max_timestamp_error(self):
         """
-        Tests for an exception with an out of bound timestamp (max + 1)
+        Tests for an exception with an out of range timestamp (max + 1)
         """
         msg = can.Message(timestamp=0xFFFFFFFF+1)
-        self.assertRaises(OverflowError, self.bus.send, msg)
+        self.assertRaises(ValueError, self.bus.send, msg)
 
     def test_rx_tx_min_timestamp(self):
         """
@@ -141,10 +141,10 @@ def test_rx_tx_min_timestamp(self):
 
     def test_rx_tx_min_timestamp_error(self):
         """
-        Tests for an exception with an out of bound timestamp (min - 1)
+        Tests for an exception with an out of range timestamp (min - 1)
         """
         msg = can.Message(timestamp=-1)
-        self.assertRaises(OverflowError, self.bus.send, msg)
+        self.assertRaises(ValueError, self.bus.send, msg)
 
 
 if __name__ == '__main__':
