def out_waiting(self):
"""Return how many bytes the in the outgoing buffer"""
flags = win32.DWORD()
comstat = win32.COMSTAT()
if not win32.ClearCommError(self._port_handle, ctypes.byref(flags), ctypes.byref(comstat)):
raise SerialException("ClearCommError failed ({!r})".format(win32.WinError()))
return comstat.cbOutQue
def in_waiting(self):
"""Return the number of bytes currently in the input buffer."""
flags = win32.DWORD()
comstat = win32.COMSTAT()
if not win32.ClearCommError(self._port_handle, ctypes.byref(flags), ctypes.byref(comstat)):
raise SerialException("ClearCommError failed ({!r})".format(win32.WinError()))
return comstat.cbInQue
def _cancel_overlapped_io(self, overlapped):
"""Cancel a blocking read operation, may be called from other thread"""
# check if read operation is pending
rc = win32.DWORD()
err = win32.GetOverlappedResult(
self._port_handle,
ctypes.byref(overlapped),
ctypes.byref(rc),
False)
if not err and win32.GetLastError() in (win32.ERROR_IO_PENDING, win32.ERROR_IO_INCOMPLETE):
# cancel, ignoring any errors (e.g. it may just have finished on its own)
win32.CancelIoEx(self._port_handle, overlapped)
def read(self, size=1):
"""\
Read size bytes from the serial port. If a timeout is set it may
return less characters as requested. With no timeout it will block
until the requested number of bytes is read.
"""
if not self.is_open:
raise PortNotOpenError()
if size > 0:
win32.ResetEvent(self._overlapped_read.hEvent)
flags = win32.DWORD()
comstat = win32.COMSTAT()
if not win32.ClearCommError(self._port_handle, ctypes.byref(flags), ctypes.byref(comstat)):
raise SerialException("ClearCommError failed ({!r})".format(win32.WinError()))
n = min(comstat.cbInQue, size) if self.timeout == 0 else size
if n > 0:
buf = ctypes.create_string_buffer(n)
rc = win32.DWORD()
read_ok = win32.ReadFile(
self._port_handle,
buf,
n,
ctypes.byref(rc),
ctypes.byref(self._overlapped_read))
if not read_ok and win32.GetLastError() not in (win32.ERROR_SUCCESS, win32.ERROR_IO_PENDING):
raise SerialException("ReadFile failed ({!r})".format(win32.WinError()))
result_ok = win32.GetOverlappedResult(
self._port_handle,
ctypes.byref(self._overlapped_read),
ctypes.byref(rc),
True)
if not result_ok:
if win32.GetLastError() != win32.ERROR_OPERATION_ABORTED:
raise SerialException("GetOverlappedResult failed ({!r})".format(win32.WinError()))
read = buf.raw[:rc.value]
else:
read = bytes()
else:
read = bytes()
return bytes(read)
def write(self, data):
"""Output the given byte string over the serial port."""
if not self.is_open:
raise PortNotOpenError()
#~ if not isinstance(data, (bytes, bytearray)):
#~ raise TypeError('expected %s or bytearray, got %s' % (bytes, type(data)))
# convert data (needed in case of memoryview instance: Py 3.1 io lib), ctypes doesn't like memoryview
data = to_bytes(data)
if data:
#~ win32event.ResetEvent(self._overlapped_write.hEvent)
n = win32.DWORD()
success = win32.WriteFile(self._port_handle, data, len(data), ctypes.byref(n), self._overlapped_write)
if self._write_timeout != 0: # if blocking (None) or w/ write timeout (>0)
if not success and win32.GetLastError() not in (win32.ERROR_SUCCESS, win32.ERROR_IO_PENDING):
raise SerialException("WriteFile failed ({!r})".format(win32.WinError()))
# Wait for the write to complete.
#~ win32.WaitForSingleObject(self._overlapped_write.hEvent, win32.INFINITE)
win32.GetOverlappedResult(self._port_handle, self._overlapped_write, ctypes.byref(n), True)
if win32.GetLastError() == win32.ERROR_OPERATION_ABORTED:
return n.value # canceled IO is no error
if n.value != len(data):
raise SerialTimeoutException('Write timeout')
return n.value
else:
errorcode = win32.ERROR_SUCCESS if success else win32.GetLastError()
if errorcode in (win32.ERROR_INVALID_USER_BUFFER, win32.ERROR_NOT_ENOUGH_MEMORY,
win32.ERROR_OPERATION_ABORTED):
return 0
elif errorcode in (win32.ERROR_SUCCESS, win32.ERROR_IO_PENDING):
# no info on true length provided by OS function in async mode
return len(data)
else:
raise SerialException("WriteFile failed ({!r})".format(win32.WinError()))
else:
return 0
def _GetCommModemStatus(self):
if not self.is_open:
raise PortNotOpenError()
stat = win32.DWORD()
win32.GetCommModemStatus(self._port_handle, ctypes.byref(stat))
return stat.value