| #! python |
| # |
| # This module implements a loop back connection receiving itself what it sent. |
| # |
| # The purpose of this module is.. well... You can run the unit tests with it. |
| # and it was so easy to implement ;-) |
| # |
| # This file is part of pySerial. https://github.com/pyserial/pyserial |
| # (C) 2001-2020 Chris Liechti <[email protected]> |
| # |
| # SPDX-License-Identifier: BSD-3-Clause |
| # |
| # URL format: loop://[option[/option...]] |
| # options: |
| # - "debug" print diagnostic messages |
| from __future__ import absolute_import |
| |
| import logging |
| import numbers |
| import time |
| try: |
| import urlparse |
| except ImportError: |
| import urllib.parse as urlparse |
| try: |
| import queue |
| except ImportError: |
| import Queue as queue |
| |
| from serial.serialutil import SerialBase, SerialException, to_bytes, iterbytes, SerialTimeoutException, PortNotOpenError |
| |
| # map log level names to constants. used in from_url() |
| LOGGER_LEVELS = { |
| 'debug': logging.DEBUG, |
| 'info': logging.INFO, |
| 'warning': logging.WARNING, |
| 'error': logging.ERROR, |
| } |
| |
| |
| class Serial(SerialBase): |
| """Serial port implementation that simulates a loop back connection in plain software.""" |
| |
| BAUDRATES = (50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, |
| 9600, 19200, 38400, 57600, 115200) |
| |
| def __init__(self, *args, **kwargs): |
| self.buffer_size = 4096 |
| self.queue = None |
| self.logger = None |
| self._cancel_write = False |
| super(Serial, self).__init__(*args, **kwargs) |
| |
| def open(self): |
| """\ |
| Open port with current settings. This may throw a SerialException |
| if the port cannot be opened. |
| """ |
| if self.is_open: |
| raise SerialException("Port is already open.") |
| self.logger = None |
| self.queue = queue.Queue(self.buffer_size) |
| |
| if self._port is None: |
| raise SerialException("Port must be configured before it can be used.") |
| # not that there is anything to open, but the function applies the |
| # options found in the URL |
| self.from_url(self.port) |
| |
| # not that there anything to configure... |
| self._reconfigure_port() |
| # all things set up get, now a clean start |
| self.is_open = True |
| if not self._dsrdtr: |
| self._update_dtr_state() |
| if not self._rtscts: |
| self._update_rts_state() |
| self.reset_input_buffer() |
| self.reset_output_buffer() |
| |
| def close(self): |
| if self.is_open: |
| self.is_open = False |
| try: |
| self.queue.put_nowait(None) |
| except queue.Full: |
| pass |
| super(Serial, self).close() |
| |
| def _reconfigure_port(self): |
| """\ |
| Set communication parameters on opened port. For the loop:// |
| protocol all settings are ignored! |
| """ |
| # not that's it of any real use, but it helps in the unit tests |
| if not isinstance(self._baudrate, numbers.Integral) or not 0 < self._baudrate < 2 ** 32: |
| raise ValueError("invalid baudrate: {!r}".format(self._baudrate)) |
| if self.logger: |
| self.logger.info('_reconfigure_port()') |
| |
| def from_url(self, url): |
| """extract host and port from an URL string""" |
| parts = urlparse.urlsplit(url) |
| if parts.scheme != "loop": |
| raise SerialException( |
| 'expected a string in the form ' |
| '"loop://[?logging={debug|info|warning|error}]": not starting ' |
| 'with loop:// ({!r})'.format(parts.scheme)) |
| try: |
| # process options now, directly altering self |
| for option, values in urlparse.parse_qs(parts.query, True).items(): |
| if option == 'logging': |
| logging.basicConfig() # XXX is that good to call it here? |
| self.logger = logging.getLogger('pySerial.loop') |
| self.logger.setLevel(LOGGER_LEVELS[values[0]]) |
| self.logger.debug('enabled logging') |
| else: |
| raise ValueError('unknown option: {!r}'.format(option)) |
| except ValueError as e: |
| raise SerialException( |
| 'expected a string in the form ' |
| '"loop://[?logging={debug|info|warning|error}]": {}'.format(e)) |
| |
| # - - - - - - - - - - - - - - - - - - - - - - - - |
| |
| @property |
| def in_waiting(self): |
| """Return the number of bytes currently in the input buffer.""" |
| if not self.is_open: |
| raise PortNotOpenError() |
| if self.logger: |
| # attention the logged value can differ from return value in |
| # threaded environments... |
| self.logger.debug('in_waiting -> {:d}'.format(self.queue.qsize())) |
| return self.queue.qsize() |
| |
| 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 self._timeout is not None and self._timeout != 0: |
| timeout = time.time() + self._timeout |
| else: |
| timeout = None |
| data = bytearray() |
| while size > 0 and self.is_open: |
| try: |
| b = self.queue.get(timeout=self._timeout) # XXX inter char timeout |
| except queue.Empty: |
| if self._timeout == 0: |
| break |
| else: |
| if b is not None: |
| data += b |
| size -= 1 |
| else: |
| break |
| # check for timeout now, after data has been read. |
| # useful for timeout = 0 (non blocking) read |
| if timeout and time.time() > timeout: |
| if self.logger: |
| self.logger.info('read timeout') |
| break |
| return bytes(data) |
| |
| def cancel_read(self): |
| self.queue.put_nowait(None) |
| |
| def cancel_write(self): |
| self._cancel_write = True |
| |
| def write(self, data): |
| """\ |
| Output the given byte string over the serial port. Can block if the |
| connection is blocked. May raise SerialException if the connection is |
| closed. |
| """ |
| self._cancel_write = False |
| if not self.is_open: |
| raise PortNotOpenError() |
| data = to_bytes(data) |
| # calculate aprox time that would be used to send the data |
| time_used_to_send = 10.0 * len(data) / self._baudrate |
| # when a write timeout is configured check if we would be successful |
| # (not sending anything, not even the part that would have time) |
| if self._write_timeout is not None and time_used_to_send > self._write_timeout: |
| # must wait so that unit test succeeds |
| time_left = self._write_timeout |
| while time_left > 0 and not self._cancel_write: |
| time.sleep(min(time_left, 0.5)) |
| time_left -= 0.5 |
| if self._cancel_write: |
| return 0 # XXX |
| raise SerialTimeoutException('Write timeout') |
| for byte in iterbytes(data): |
| self.queue.put(byte, timeout=self._write_timeout) |
| return len(data) |
| |
| def reset_input_buffer(self): |
| """Clear input buffer, discarding all that is in the buffer.""" |
| if not self.is_open: |
| raise PortNotOpenError() |
| if self.logger: |
| self.logger.info('reset_input_buffer()') |
| try: |
| while self.queue.qsize(): |
| self.queue.get_nowait() |
| except queue.Empty: |
| pass |
| |
| def reset_output_buffer(self): |
| """\ |
| Clear output buffer, aborting the current output and |
| discarding all that is in the buffer. |
| """ |
| if not self.is_open: |
| raise PortNotOpenError() |
| if self.logger: |
| self.logger.info('reset_output_buffer()') |
| try: |
| while self.queue.qsize(): |
| self.queue.get_nowait() |
| except queue.Empty: |
| pass |
| |
| @property |
| def out_waiting(self): |
| """Return how many bytes the in the outgoing buffer""" |
| if not self.is_open: |
| raise PortNotOpenError() |
| if self.logger: |
| # attention the logged value can differ from return value in |
| # threaded environments... |
| self.logger.debug('out_waiting -> {:d}'.format(self.queue.qsize())) |
| return self.queue.qsize() |
| |
| def _update_break_state(self): |
| """\ |
| Set break: Controls TXD. When active, to transmitting is |
| possible. |
| """ |
| if self.logger: |
| self.logger.info('_update_break_state({!r})'.format(self._break_state)) |
| |
| def _update_rts_state(self): |
| """Set terminal status line: Request To Send""" |
| if self.logger: |
| self.logger.info('_update_rts_state({!r}) -> state of CTS'.format(self._rts_state)) |
| |
| def _update_dtr_state(self): |
| """Set terminal status line: Data Terminal Ready""" |
| if self.logger: |
| self.logger.info('_update_dtr_state({!r}) -> state of DSR'.format(self._dtr_state)) |
| |
| @property |
| def cts(self): |
| """Read terminal status line: Clear To Send""" |
| if not self.is_open: |
| raise PortNotOpenError() |
| if self.logger: |
| self.logger.info('CTS -> state of RTS ({!r})'.format(self._rts_state)) |
| return self._rts_state |
| |
| @property |
| def dsr(self): |
| """Read terminal status line: Data Set Ready""" |
| if self.logger: |
| self.logger.info('DSR -> state of DTR ({!r})'.format(self._dtr_state)) |
| return self._dtr_state |
| |
| @property |
| def ri(self): |
| """Read terminal status line: Ring Indicator""" |
| if not self.is_open: |
| raise PortNotOpenError() |
| if self.logger: |
| self.logger.info('returning dummy for RI') |
| return False |
| |
| @property |
| def cd(self): |
| """Read terminal status line: Carrier Detect""" |
| if not self.is_open: |
| raise PortNotOpenError() |
| if self.logger: |
| self.logger.info('returning dummy for CD') |
| return True |
| |
| # - - - platform specific - - - |
| # None so far |
| |
| |
| # simple client test |
| if __name__ == '__main__': |
| import sys |
| s = Serial('loop://') |
| sys.stdout.write('{}\n'.format(s)) |
| |
| sys.stdout.write("write...\n") |
| s.write("hello\n") |
| s.flush() |
| sys.stdout.write("read: {!r}\n".format(s.read(5))) |
| |
| s.close() |
