360 lines
14 KiB
Python
360 lines
14 KiB
Python
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#! python
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#
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# This module implements a simple socket based client.
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# It does not support changing any port parameters and will silently ignore any
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# requests to do so.
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#
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# The purpose of this module is that applications using pySerial can connect to
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# TCP/IP to serial port converters that do not support RFC 2217.
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#
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# This file is part of pySerial. https://github.com/pyserial/pyserial
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# (C) 2001-2015 Chris Liechti <cliechti@gmx.net>
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#
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# SPDX-License-Identifier: BSD-3-Clause
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#
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# URL format: socket://<host>:<port>[/option[/option...]]
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# options:
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# - "debug" print diagnostic messages
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from __future__ import absolute_import
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import errno
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import logging
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import select
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import socket
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import time
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try:
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import urlparse
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except ImportError:
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import urllib.parse as urlparse
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from serial.serialutil import SerialBase, SerialException, to_bytes, \
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PortNotOpenError, SerialTimeoutException, Timeout
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# map log level names to constants. used in from_url()
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LOGGER_LEVELS = {
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'debug': logging.DEBUG,
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'info': logging.INFO,
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'warning': logging.WARNING,
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'error': logging.ERROR,
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}
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POLL_TIMEOUT = 5
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class Serial(SerialBase):
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"""Serial port implementation for plain sockets."""
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BAUDRATES = (50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
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9600, 19200, 38400, 57600, 115200)
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def open(self):
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"""\
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Open port with current settings. This may throw a SerialException
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if the port cannot be opened.
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"""
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self.logger = None
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if self._port is None:
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raise SerialException("Port must be configured before it can be used.")
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if self.is_open:
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raise SerialException("Port is already open.")
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try:
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# timeout is used for write timeout support :/ and to get an initial connection timeout
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self._socket = socket.create_connection(self.from_url(self.portstr), timeout=POLL_TIMEOUT)
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except Exception as msg:
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self._socket = None
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raise SerialException("Could not open port {}: {}".format(self.portstr, msg))
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# after connecting, switch to non-blocking, we're using select
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self._socket.setblocking(False)
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# not that there is anything to configure...
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self._reconfigure_port()
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# all things set up get, now a clean start
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self.is_open = True
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if not self._dsrdtr:
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self._update_dtr_state()
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if not self._rtscts:
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self._update_rts_state()
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self.reset_input_buffer()
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self.reset_output_buffer()
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def _reconfigure_port(self):
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"""\
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Set communication parameters on opened port. For the socket://
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protocol all settings are ignored!
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"""
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if self._socket is None:
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raise SerialException("Can only operate on open ports")
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if self.logger:
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self.logger.info('ignored port configuration change')
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def close(self):
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"""Close port"""
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if self.is_open:
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if self._socket:
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try:
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self._socket.shutdown(socket.SHUT_RDWR)
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self._socket.close()
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except:
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# ignore errors.
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pass
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self._socket = None
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self.is_open = False
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# in case of quick reconnects, give the server some time
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time.sleep(0.3)
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def from_url(self, url):
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"""extract host and port from an URL string"""
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parts = urlparse.urlsplit(url)
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if parts.scheme != "socket":
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raise SerialException(
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'expected a string in the form '
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'"socket://<host>:<port>[?logging={debug|info|warning|error}]": '
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'not starting with socket:// ({!r})'.format(parts.scheme))
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try:
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# process options now, directly altering self
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for option, values in urlparse.parse_qs(parts.query, True).items():
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if option == 'logging':
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logging.basicConfig() # XXX is that good to call it here?
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self.logger = logging.getLogger('pySerial.socket')
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self.logger.setLevel(LOGGER_LEVELS[values[0]])
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self.logger.debug('enabled logging')
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else:
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raise ValueError('unknown option: {!r}'.format(option))
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if not 0 <= parts.port < 65536:
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raise ValueError("port not in range 0...65535")
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except ValueError as e:
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raise SerialException(
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'expected a string in the form '
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'"socket://<host>:<port>[?logging={debug|info|warning|error}]": {}'.format(e))
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return (parts.hostname, parts.port)
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# - - - - - - - - - - - - - - - - - - - - - - - -
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@property
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def in_waiting(self):
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"""Return the number of bytes currently in the input buffer."""
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if not self.is_open:
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raise PortNotOpenError()
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# Poll the socket to see if it is ready for reading.
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# If ready, at least one byte will be to read.
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lr, lw, lx = select.select([self._socket], [], [], 0)
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return len(lr)
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# select based implementation, similar to posix, but only using socket API
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# to be portable, additionally handle socket timeout which is used to
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# emulate write timeouts
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def read(self, size=1):
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"""\
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Read size bytes from the serial port. If a timeout is set it may
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return less characters as requested. With no timeout it will block
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until the requested number of bytes is read.
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"""
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if not self.is_open:
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raise PortNotOpenError()
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read = bytearray()
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timeout = Timeout(self._timeout)
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while len(read) < size:
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try:
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ready, _, _ = select.select([self._socket], [], [], timeout.time_left())
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# If select was used with a timeout, and the timeout occurs, it
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# returns with empty lists -> thus abort read operation.
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# For timeout == 0 (non-blocking operation) also abort when
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# there is nothing to read.
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if not ready:
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break # timeout
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buf = self._socket.recv(size - len(read))
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# read should always return some data as select reported it was
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# ready to read when we get to this point, unless it is EOF
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if not buf:
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raise SerialException('socket disconnected')
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read.extend(buf)
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except OSError as e:
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# this is for Python 3.x where select.error is a subclass of
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# OSError ignore BlockingIOErrors and EINTR. other errors are shown
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# https://www.python.org/dev/peps/pep-0475.
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if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
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raise SerialException('read failed: {}'.format(e))
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except (select.error, socket.error) as e:
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# this is for Python 2.x
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# ignore BlockingIOErrors and EINTR. all errors are shown
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# see also http://www.python.org/dev/peps/pep-3151/#select
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if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
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raise SerialException('read failed: {}'.format(e))
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if timeout.expired():
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break
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return bytes(read)
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def write(self, data):
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"""\
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Output the given byte string over the serial port. Can block if the
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connection is blocked. May raise SerialException if the connection is
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closed.
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"""
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if not self.is_open:
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raise PortNotOpenError()
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d = to_bytes(data)
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tx_len = length = len(d)
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timeout = Timeout(self._write_timeout)
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while tx_len > 0:
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try:
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n = self._socket.send(d)
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if timeout.is_non_blocking:
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# Zero timeout indicates non-blocking - simply return the
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# number of bytes of data actually written
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return n
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elif not timeout.is_infinite:
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# when timeout is set, use select to wait for being ready
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# with the time left as timeout
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if timeout.expired():
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raise SerialTimeoutException('Write timeout')
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_, ready, _ = select.select([], [self._socket], [], timeout.time_left())
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if not ready:
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raise SerialTimeoutException('Write timeout')
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else:
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assert timeout.time_left() is None
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# wait for write operation
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_, ready, _ = select.select([], [self._socket], [], None)
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if not ready:
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raise SerialException('write failed (select)')
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d = d[n:]
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tx_len -= n
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except SerialException:
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raise
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except OSError as e:
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# this is for Python 3.x where select.error is a subclass of
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# OSError ignore BlockingIOErrors and EINTR. other errors are shown
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# https://www.python.org/dev/peps/pep-0475.
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if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
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raise SerialException('write failed: {}'.format(e))
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except select.error as e:
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# this is for Python 2.x
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# ignore BlockingIOErrors and EINTR. all errors are shown
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# see also http://www.python.org/dev/peps/pep-3151/#select
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if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
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raise SerialException('write failed: {}'.format(e))
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if not timeout.is_non_blocking and timeout.expired():
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raise SerialTimeoutException('Write timeout')
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return length - len(d)
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def reset_input_buffer(self):
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"""Clear input buffer, discarding all that is in the buffer."""
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if not self.is_open:
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raise PortNotOpenError()
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# just use recv to remove input, while there is some
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ready = True
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while ready:
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ready, _, _ = select.select([self._socket], [], [], 0)
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try:
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if ready:
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ready = self._socket.recv(4096)
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except OSError as e:
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# this is for Python 3.x where select.error is a subclass of
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# OSError ignore BlockingIOErrors and EINTR. other errors are shown
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# https://www.python.org/dev/peps/pep-0475.
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if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
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raise SerialException('read failed: {}'.format(e))
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except (select.error, socket.error) as e:
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# this is for Python 2.x
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# ignore BlockingIOErrors and EINTR. all errors are shown
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# see also http://www.python.org/dev/peps/pep-3151/#select
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if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
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raise SerialException('read failed: {}'.format(e))
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def reset_output_buffer(self):
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"""\
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Clear output buffer, aborting the current output and
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discarding all that is in the buffer.
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"""
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if not self.is_open:
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raise PortNotOpenError()
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if self.logger:
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self.logger.info('ignored reset_output_buffer')
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def send_break(self, duration=0.25):
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"""\
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Send break condition. Timed, returns to idle state after given
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duration.
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"""
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if not self.is_open:
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raise PortNotOpenError()
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if self.logger:
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self.logger.info('ignored send_break({!r})'.format(duration))
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def _update_break_state(self):
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"""Set break: Controls TXD. When active, to transmitting is
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possible."""
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if self.logger:
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self.logger.info('ignored _update_break_state({!r})'.format(self._break_state))
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def _update_rts_state(self):
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"""Set terminal status line: Request To Send"""
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if self.logger:
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self.logger.info('ignored _update_rts_state({!r})'.format(self._rts_state))
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def _update_dtr_state(self):
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"""Set terminal status line: Data Terminal Ready"""
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if self.logger:
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self.logger.info('ignored _update_dtr_state({!r})'.format(self._dtr_state))
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@property
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def cts(self):
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"""Read terminal status line: Clear To Send"""
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if not self.is_open:
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raise PortNotOpenError()
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if self.logger:
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self.logger.info('returning dummy for cts')
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return True
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@property
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def dsr(self):
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"""Read terminal status line: Data Set Ready"""
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if not self.is_open:
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raise PortNotOpenError()
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if self.logger:
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self.logger.info('returning dummy for dsr')
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return True
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@property
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def ri(self):
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"""Read terminal status line: Ring Indicator"""
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if not self.is_open:
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raise PortNotOpenError()
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if self.logger:
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self.logger.info('returning dummy for ri')
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return False
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@property
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def cd(self):
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"""Read terminal status line: Carrier Detect"""
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if not self.is_open:
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raise PortNotOpenError()
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if self.logger:
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self.logger.info('returning dummy for cd)')
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return True
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# - - - platform specific - - -
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# works on Linux and probably all the other POSIX systems
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def fileno(self):
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"""Get the file handle of the underlying socket for use with select"""
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return self._socket.fileno()
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#
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# simple client test
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if __name__ == '__main__':
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import sys
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s = Serial('socket://localhost:7000')
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sys.stdout.write('{}\n'.format(s))
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sys.stdout.write("write...\n")
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s.write(b"hello\n")
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s.flush()
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sys.stdout.write("read: {}\n".format(s.read(5)))
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s.close()
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