Send HighPriority Message to flush VectorBus Tx buffer (#1636)

* Refactor flush_tx_queue for VectorBus

* Remove test_flush_tx_buffer_mocked

Implementation cannot be tested due to Vector TX queue being not accessible

* Update formatting in flush_tx_queue

* Add tests for VectorBus flush_tx_queue

* Refactor docstring for VectorBus flush_tx_queue

Author: deronek

can/interfaces/vector/canlib.py

@@ -876,7 +876,40 @@ def _build_xl_can_tx_event(msg: Message) -> xlclass.XLcanTxEvent:
         return xl_can_tx_event
 
     def flush_tx_buffer(self) -> None:
-        self.xldriver.xlCanFlushTransmitQueue(self.port_handle, self.mask)
+        """
+        Flush the TX buffer of the bus.
+
+        Implementation does not use function ``xlCanFlushTransmitQueue`` of the XL driver, as it works only
+        for XL family devices.
+
+        .. warning::
+            Using this function will flush the queue and send a high voltage message (ID = 0, DLC = 0, no data).
+        """
+        if self._can_protocol is CanProtocol.CAN_FD:
+            xl_can_tx_event = xlclass.XLcanTxEvent()
+            xl_can_tx_event.tag = xldefine.XL_CANFD_TX_EventTags.XL_CAN_EV_TAG_TX_MSG
+            xl_can_tx_event.tagData.canMsg.msgFlags |= (
+                xldefine.XL_CANFD_TX_MessageFlags.XL_CAN_TXMSG_FLAG_HIGHPRIO
+            )
+
+            self.xldriver.xlCanTransmitEx(
+                self.port_handle,
+                self.mask,
+                ctypes.c_uint(1),
+                ctypes.c_uint(0),
+                xl_can_tx_event,
+            )
+        else:
+            xl_event = xlclass.XLevent()
+            xl_event.tag = xldefine.XL_EventTags.XL_TRANSMIT_MSG
+            xl_event.tagData.msg.flags |= (
+                xldefine.XL_MessageFlags.XL_CAN_MSG_FLAG_OVERRUN
+                | xldefine.XL_MessageFlags.XL_CAN_MSG_FLAG_WAKEUP
+            )
+
+            self.xldriver.xlCanTransmit(
+                self.port_handle, self.mask, ctypes.c_uint(1), xl_event
+            )
 
     def shutdown(self) -> None:
         super().shutdown()

test/test_vector.py

@@ -613,7 +613,38 @@ def test_receive_fd_non_msg_event() -> None:
 def test_flush_tx_buffer_mocked(mock_xldriver) -> None:
     bus = can.Bus(channel=0, interface="vector", _testing=True)
     bus.flush_tx_buffer()
-    can.interfaces.vector.canlib.xldriver.xlCanFlushTransmitQueue.assert_called()
+    transmit_args = can.interfaces.vector.canlib.xldriver.xlCanTransmit.call_args[0]
+
+    num_msg = transmit_args[2]
+    assert num_msg.value == ctypes.c_uint(1).value
+
+    event = transmit_args[3]
+    assert isinstance(event, xlclass.XLevent)
+    assert event.tag & xldefine.XL_EventTags.XL_TRANSMIT_MSG
+    assert event.tagData.msg.flags & (
+        xldefine.XL_MessageFlags.XL_CAN_MSG_FLAG_OVERRUN
+        | xldefine.XL_MessageFlags.XL_CAN_MSG_FLAG_WAKEUP
+    )
+
+
+def test_flush_tx_buffer_fd_mocked(mock_xldriver) -> None:
+    bus = can.Bus(channel=0, interface="vector", fd=True, _testing=True)
+    bus.flush_tx_buffer()
+    transmit_args = can.interfaces.vector.canlib.xldriver.xlCanTransmitEx.call_args[0]
+
+    num_msg = transmit_args[2]
+    assert num_msg.value == ctypes.c_uint(1).value
+
+    num_msg_sent = transmit_args[3]
+    assert num_msg_sent.value == ctypes.c_uint(0).value
+
+    event = transmit_args[4]
+    assert isinstance(event, xlclass.XLcanTxEvent)
+    assert event.tag & xldefine.XL_CANFD_TX_EventTags.XL_CAN_EV_TAG_TX_MSG
+    assert (
+        event.tagData.canMsg.msgFlags
+        & xldefine.XL_CANFD_TX_MessageFlags.XL_CAN_TXMSG_FLAG_HIGHPRIO
+    )
 
 
 @pytest.mark.skipif(not XLDRIVER_FOUND, reason="Vector XL API is unavailable")