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.hComPort: raise portNotOpenError if size > 0: win32.ResetEvent(self._overlappedRead.hEvent) flags = win32.DWORD() comstat = win32.COMSTAT() if not win32.ClearCommError(self.hComPort, ctypes.byref(flags), ctypes.byref(comstat)): raise SerialException('call to ClearCommError failed') if self.timeout == 0: n = min(comstat.cbInQue, size) if n > 0: buf = ctypes.create_string_buffer(n) rc = win32.DWORD() err = win32.ReadFile(self.hComPort, buf, n, ctypes.byref(rc), ctypes.byref(self._overlappedRead)) if not err and win32.GetLastError() != win32.ERROR_IO_PENDING: raise SerialException("ReadFile failed (%r)" % ctypes.WinError()) err = win32.WaitForSingleObject(self._overlappedRead.hEvent, win32.INFINITE) read = buf.raw[:rc.value] else: read = bytes() else: buf = ctypes.create_string_buffer(size) rc = win32.DWORD() err = win32.ReadFile(self.hComPort, buf, size, ctypes.byref(rc), ctypes.byref(self._overlappedRead)) if not err and win32.GetLastError() != win32.ERROR_IO_PENDING: raise SerialException("ReadFile failed (%r)" % ctypes.WinError()) err = win32.GetOverlappedResult(self.hComPort, ctypes.byref(self._overlappedRead), ctypes.byref(rc), True) read = buf.raw[:rc.value] else: read = bytes() return bytes(read)
def write(self, data): """Output the given string over the serial port.""" if not self.hComPort: 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._overlappedWrite.hEvent) n = win32.DWORD() err = win32.WriteFile(self.hComPort, data, len(data), ctypes.byref(n), self._overlappedWrite) if not err and win32.GetLastError() != win32.ERROR_IO_PENDING: raise SerialException("WriteFile failed (%r)" % ctypes.WinError()) if self._writeTimeout != 0: # if blocking (None) or w/ write timeout (>0) # Wait for the write to complete. #~ win32.WaitForSingleObject(self._overlappedWrite.hEvent, win32.INFINITE) err = win32.GetOverlappedResult(self.hComPort, self._overlappedWrite, ctypes.byref(n), True) if n.value != len(data): raise writeTimeoutError return n.value else: return 0
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 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( ctypes.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 writeTimeoutError 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( ctypes.WinError())) else: return 0
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( ctypes.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( ctypes.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( ctypes.WinError())) read = buf.raw[:rc.value] else: read = bytes() else: read = bytes() return bytes(read)