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#! python
#
# Base class and support functions used by various backends.
#
# This file is part of pySerial. https://github.com/pyserial/pyserial
# (C) 2001-2016 Chris Liechti <cliechti@gmx.net>
#
# SPDX-License-Identifier: BSD-3-Clause
import io
import time
# ``memoryview`` was introduced in Python 2.7 and ``bytes(some_memoryview)``
# isn't returning the contents (very unfortunate). Therefore we need special
# cases and test for it. Ensure that there is a ``memoryview`` object for older
# Python versions. This is easier than making every test dependent on its
# existence.
try:
memoryview
except (NameError, AttributeError):
# implementation does not matter as we do not really use it.
# it just must not inherit from something else we might care for.
class memoryview(object): # pylint: disable=redefined-builtin,invalid-name
pass
try:
unicode
except (NameError, AttributeError):
unicode = str # for Python 3, pylint: disable=redefined-builtin,invalid-name
try:
basestring
except (NameError, AttributeError):
basestring = (str,) # for Python 3, pylint: disable=redefined-builtin,invalid-name
# "for byte in data" fails for python3 as it returns ints instead of bytes
def iterbytes(b):
"""Iterate over bytes, returning bytes instead of ints (python3)"""
if isinstance(b, memoryview):
b = b.tobytes()
i = 0
while True:
a = b[i:i + 1]
i += 1
if a:
yield a
else:
break
# all Python versions prior 3.x convert ``str([17])`` to '[17]' instead of '\x11'
# so a simple ``bytes(sequence)`` doesn't work for all versions
def to_bytes(seq):
"""convert a sequence to a bytes type"""
if isinstance(seq, bytes):
return seq
elif isinstance(seq, bytearray):
return bytes(seq)
elif isinstance(seq, memoryview):
return seq.tobytes()
elif isinstance(seq, unicode):
raise TypeError('unicode strings are not supported, please encode to bytes: {!r}'.format(seq))
else:
# handle list of integers and bytes (one or more items) for Python 2 and 3
return bytes(bytearray(seq))
# create control bytes
XON = to_bytes([17])
XOFF = to_bytes([19])
CR = to_bytes([13])
LF = to_bytes([10])
PARITY_NONE, PARITY_EVEN, PARITY_ODD, PARITY_MARK, PARITY_SPACE = 'N', 'E', 'O', 'M', 'S'
STOPBITS_ONE, STOPBITS_ONE_POINT_FIVE, STOPBITS_TWO = (1, 1.5, 2)
FIVEBITS, SIXBITS, SEVENBITS, EIGHTBITS = (5, 6, 7, 8)
PARITY_NAMES = {
PARITY_NONE: 'None',
PARITY_EVEN: 'Even',
PARITY_ODD: 'Odd',
PARITY_MARK: 'Mark',
PARITY_SPACE: 'Space',
}
class SerialException(IOError):
"""Base class for serial port related exceptions."""
class SerialTimeoutException(SerialException):
"""Write timeouts give an exception"""
writeTimeoutError = SerialTimeoutException('Write timeout')
portNotOpenError = SerialException('Attempting to use a port that is not open')
class Timeout(object):
"""\
Abstraction for timeout operations. Using time.monotonic() if available
or time.time() in all other cases.
The class can also be initialized with 0 or None, in order to support
non-blocking and fully blocking I/O operations. The attributes
is_non_blocking and is_infinite are set accordingly.
"""
if hasattr(time, 'monotonic'):
# Timeout implementation with time.monotonic(). This function is only
# supported by Python 3.3 and above. It returns a time in seconds
# (float) just as time.time(), but is not affected by system clock
# adjustments.
TIME = time.monotonic
else:
# Timeout implementation with time.time(). This is compatible with all
# Python versions but has issues if the clock is adjusted while the
# timeout is running.
TIME = time.time
def __init__(self, duration):
"""Initialize a timeout with given duration"""
self.is_infinite = (duration is None)
self.is_non_blocking = (duration == 0)
self.duration = duration
if duration is not None:
self.target_time = self.TIME() + duration
else:
self.target_time = None
def expired(self):
"""Return a boolean, telling if the timeout has expired"""
return self.target_time is not None and self.time_left() <= 0
def time_left(self):
"""Return how many seconds are left until the timeout expires"""
if self.is_non_blocking:
return 0
elif self.is_infinite:
return None
else:
delta = self.target_time - self.TIME()
if delta > self.duration:
# clock jumped, recalculate
self.target_time = self.TIME() + self.duration
return self.duration
else:
return max(0, delta)
def restart(self, duration):
"""\
Restart a timeout, only supported if a timeout was already set up
before.
"""
self.duration = duration
self.target_time = self.TIME() + duration
class SerialBase(io.RawIOBase):
"""\
Serial port base class. Provides __init__ function and properties to
get/set port settings.
"""
# default values, may be overridden in subclasses that do not support all values
BAUDRATES = (50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
9600, 19200, 38400, 57600, 115200, 230400, 460800, 500000,
576000, 921600, 1000000, 1152000, 1500000, 2000000, 2500000,
3000000, 3500000, 4000000)
BYTESIZES = (FIVEBITS, SIXBITS, SEVENBITS, EIGHTBITS)
PARITIES = (PARITY_NONE, PARITY_EVEN, PARITY_ODD, PARITY_MARK, PARITY_SPACE)
STOPBITS = (STOPBITS_ONE, STOPBITS_ONE_POINT_FIVE, STOPBITS_TWO)
def __init__(self,
port=None,
baudrate=9600,
bytesize=EIGHTBITS,
parity=PARITY_NONE,
stopbits=STOPBITS_ONE,
timeout=None,
xonxoff=False,
rtscts=False,
write_timeout=None,
dsrdtr=False,
inter_byte_timeout=None,
exclusive=None,
**kwargs):
"""\
Initialize comm port object. If a "port" is given, then the port will be
opened immediately. Otherwise a Serial port object in closed state
is returned.
"""
self.is_open = False
self.portstr = None
self.name = None
# correct values are assigned below through properties
self._port = None
self._baudrate = None
self._bytesize = None
self._parity = None
self._stopbits = None
self._timeout = None
self._write_timeout = None
self._xonxoff = None
self._rtscts = None
self._dsrdtr = None
self._inter_byte_timeout = None
self._rs485_mode = None # disabled by default
self._rts_state = True
self._dtr_state = True
self._break_state = False
self._exclusive = None
# assign values using get/set methods using the properties feature
self.port = port
self.baudrate = baudrate
self.bytesize = bytesize
self.parity = parity
self.stopbits = stopbits
self.timeout = timeout
self.write_timeout = write_timeout
self.xonxoff = xonxoff
self.rtscts = rtscts
self.dsrdtr = dsrdtr
self.inter_byte_timeout = inter_byte_timeout
self.exclusive = exclusive
# watch for backward compatible kwargs
if 'writeTimeout' in kwargs:
self.write_timeout = kwargs.pop('writeTimeout')
if 'interCharTimeout' in kwargs:
self.inter_byte_timeout = kwargs.pop('interCharTimeout')
if kwargs:
raise ValueError('unexpected keyword arguments: {!r}'.format(kwargs))
if port is not None:
self.open()
# - - - - - - - - - - - - - - - - - - - - - - - -
# to be implemented by subclasses:
# def open(self):
# def close(self):
# - - - - - - - - - - - - - - - - - - - - - - - -
@property
def port(self):
"""\
Get the current port setting. The value that was passed on init or using
setPort() is passed back.
"""
return self._port
@port.setter
def port(self, port):
"""\
Change the port.
"""
if port is not None and not isinstance(port, basestring):
raise ValueError('"port" must be None or a string, not {}'.format(type(port)))
was_open = self.is_open
if was_open:
self.close()
self.portstr = port
self._port = port
self.name = self.portstr
if was_open:
self.open()
@property
def baudrate(self):
"""Get the current baud rate setting."""
return self._baudrate
@baudrate.setter
def baudrate(self, baudrate):
"""\
Change baud rate. It raises a ValueError if the port is open and the
baud rate is not possible. If the port is closed, then the value is
accepted and the exception is raised when the port is opened.
"""
try:
b = int(baudrate)
except TypeError:
raise ValueError("Not a valid baudrate: {!r}".format(baudrate))
else:
if b < 0:
raise ValueError("Not a valid baudrate: {!r}".format(baudrate))
self._baudrate = b
if self.is_open:
self._reconfigure_port()
@property
def bytesize(self):
"""Get the current byte size setting."""
return self._bytesize
@bytesize.setter
def bytesize(self, bytesize):
"""Change byte size."""
if bytesize not in self.BYTESIZES:
raise ValueError("Not a valid byte size: {!r}".format(bytesize))
self._bytesize = bytesize
if self.is_open:
self._reconfigure_port()
@property
def exclusive(self):
"""Get the current exclusive access setting."""
return self._exclusive
@exclusive.setter
def exclusive(self, exclusive):
"""Change the exclusive access setting."""
self._exclusive = exclusive
if self.is_open:
self._reconfigure_port()
@property
def parity(self):
"""Get the current parity setting."""
return self._parity
@parity.setter
def parity(self, parity):
"""Change parity setting."""
if parity not in self.PARITIES:
raise ValueError("Not a valid parity: {!r}".format(parity))
self._parity = parity
if self.is_open:
self._reconfigure_port()
@property
def stopbits(self):
"""Get the current stop bits setting."""
return self._stopbits
@stopbits.setter
def stopbits(self, stopbits):
"""Change stop bits size."""
if stopbits not in self.STOPBITS:
raise ValueError("Not a valid stop bit size: {!r}".format(stopbits))
self._stopbits = stopbits
if self.is_open:
self._reconfigure_port()
@property
def timeout(self):
"""Get the current timeout setting."""
return self._timeout
@timeout.setter
def timeout(self, timeout):
"""Change timeout setting."""
if timeout is not None:
try:
timeout + 1 # test if it's a number, will throw a TypeError if not...
except TypeError:
raise ValueError("Not a valid timeout: {!r}".format(timeout))
if timeout < 0:
raise ValueError("Not a valid timeout: {!r}".format(timeout))
self._timeout = timeout
if self.is_open:
self._reconfigure_port()
@property
def write_timeout(self):
"""Get the current timeout setting."""
return self._write_timeout
@write_timeout.setter
def write_timeout(self, timeout):
"""Change timeout setting."""
if timeout is not None:
if timeout < 0:
raise ValueError("Not a valid timeout: {!r}".format(timeout))
try:
timeout + 1 # test if it's a number, will throw a TypeError if not...
except TypeError:
raise ValueError("Not a valid timeout: {!r}".format(timeout))
self._write_timeout = timeout
if self.is_open:
self._reconfigure_port()
@property
def inter_byte_timeout(self):
"""Get the current inter-character timeout setting."""
return self._inter_byte_timeout
@inter_byte_timeout.setter
def inter_byte_timeout(self, ic_timeout):
"""Change inter-byte timeout setting."""
if ic_timeout is not None:
if ic_timeout < 0:
raise ValueError("Not a valid timeout: {!r}".format(ic_timeout))
try:
ic_timeout + 1 # test if it's a number, will throw a TypeError if not...
except TypeError:
raise ValueError("Not a valid timeout: {!r}".format(ic_timeout))
self._inter_byte_timeout = ic_timeout
if self.is_open:
self._reconfigure_port()
@property
def xonxoff(self):
"""Get the current XON/XOFF setting."""
return self._xonxoff
@xonxoff.setter
def xonxoff(self, xonxoff):
"""Change XON/XOFF setting."""
self._xonxoff = xonxoff
if self.is_open:
self._reconfigure_port()
@property
def rtscts(self):
"""Get the current RTS/CTS flow control setting."""
return self._rtscts
@rtscts.setter
def rtscts(self, rtscts):
"""Change RTS/CTS flow control setting."""
self._rtscts = rtscts
if self.is_open:
self._reconfigure_port()
@property
def dsrdtr(self):
"""Get the current DSR/DTR flow control setting."""
return self._dsrdtr
@dsrdtr.setter
def dsrdtr(self, dsrdtr=None):
"""Change DsrDtr flow control setting."""
if dsrdtr is None:
# if not set, keep backwards compatibility and follow rtscts setting
self._dsrdtr = self._rtscts
else:
# if defined independently, follow its value
self._dsrdtr = dsrdtr
if self.is_open:
self._reconfigure_port()
@property
def rts(self):
return self._rts_state
@rts.setter
def rts(self, value):
self._rts_state = value
if self.is_open:
self._update_rts_state()
@property
def dtr(self):
return self._dtr_state
@dtr.setter
def dtr(self, value):
self._dtr_state = value
if self.is_open:
self._update_dtr_state()
@property
def break_condition(self):
return self._break_state
@break_condition.setter
def break_condition(self, value):
self._break_state = value
if self.is_open:
self._update_break_state()
# - - - - - - - - - - - - - - - - - - - - - - - -
# functions useful for RS-485 adapters
@property
def rs485_mode(self):
"""\
Enable RS485 mode and apply new settings, set to None to disable.
See serial.rs485.RS485Settings for more info about the value.
"""
return self._rs485_mode
@rs485_mode.setter
def rs485_mode(self, rs485_settings):
self._rs485_mode = rs485_settings
if self.is_open:
self._reconfigure_port()
# - - - - - - - - - - - - - - - - - - - - - - - -
_SAVED_SETTINGS = ('baudrate', 'bytesize', 'parity', 'stopbits', 'xonxoff',
'dsrdtr', 'rtscts', 'timeout', 'write_timeout',
'inter_byte_timeout')
def get_settings(self):
"""\
Get current port settings as a dictionary. For use with
apply_settings().
"""
return dict([(key, getattr(self, '_' + key)) for key in self._SAVED_SETTINGS])
def apply_settings(self, d):
"""\
Apply stored settings from a dictionary returned from
get_settings(). It's allowed to delete keys from the dictionary. These
values will simply left unchanged.
"""
for key in self._SAVED_SETTINGS:
if key in d and d[key] != getattr(self, '_' + key): # check against internal "_" value
setattr(self, key, d[key]) # set non "_" value to use properties write function
# - - - - - - - - - - - - - - - - - - - - - - - -
def __repr__(self):
"""String representation of the current port settings and its state."""
return '{name}<id=0x{id:x}, open={p.is_open}>(port={p.portstr!r}, ' \
'baudrate={p.baudrate!r}, bytesize={p.bytesize!r}, parity={p.parity!r}, ' \
'stopbits={p.stopbits!r}, timeout={p.timeout!r}, xonxoff={p.xonxoff!r}, ' \
'rtscts={p.rtscts!r}, dsrdtr={p.dsrdtr!r})'.format(
name=self.__class__.__name__, id=id(self), p=self)
# - - - - - - - - - - - - - - - - - - - - - - - -
# compatibility with io library
# pylint: disable=invalid-name,missing-docstring
def readable(self):
return True
def writable(self):
return True
def seekable(self):
return False
def readinto(self, b):
data = self.read(len(b))
n = len(data)
try:
b[:n] = data
except TypeError as err:
import array
if not isinstance(b, array.array):
raise err
b[:n] = array.array('b', data)
return n
# - - - - - - - - - - - - - - - - - - - - - - - -
# context manager
def __enter__(self):
if not self.is_open:
self.open()
return self
def __exit__(self, *args, **kwargs):
self.close()
# - - - - - - - - - - - - - - - - - - - - - - - -
def send_break(self, duration=0.25):
"""\
Send break condition. Timed, returns to idle state after given
duration.
"""
if not self.is_open:
raise portNotOpenError
self.break_condition = True
time.sleep(duration)
self.break_condition = False
# - - - - - - - - - - - - - - - - - - - - - - - -
# backwards compatibility / deprecated functions
def flushInput(self):
self.reset_input_buffer()
def flushOutput(self):
self.reset_output_buffer()
def inWaiting(self):
return self.in_waiting
def sendBreak(self, duration=0.25):
self.send_break(duration)
def setRTS(self, value=1):
self.rts = value
def setDTR(self, value=1):
self.dtr = value
def getCTS(self):
return self.cts
def getDSR(self):
return self.dsr
def getRI(self):
return self.ri
def getCD(self):
return self.cd
def setPort(self, port):
self.port = port
@property
def writeTimeout(self):
return self.write_timeout
@writeTimeout.setter
def writeTimeout(self, timeout):
self.write_timeout = timeout
@property
def interCharTimeout(self):
return self.inter_byte_timeout
@interCharTimeout.setter
def interCharTimeout(self, interCharTimeout):
self.inter_byte_timeout = interCharTimeout
def getSettingsDict(self):
return self.get_settings()
def applySettingsDict(self, d):
self.apply_settings(d)
def isOpen(self):
return self.is_open
# - - - - - - - - - - - - - - - - - - - - - - - -
# additional functionality
def read_all(self):
"""\
Read all bytes currently available in the buffer of the OS.
"""
return self.read(self.in_waiting)
def read_until(self, terminator=LF, size=None):
"""\
Read until a termination sequence is found ('\n' by default), the size
is exceeded or until timeout occurs.
"""
lenterm = len(terminator)
line = bytearray()
timeout = Timeout(self._timeout)
while True:
c = self.read(1)
if c:
line += c
if line[-lenterm:] == terminator:
break
if size is not None and len(line) >= size:
break
else:
break
if timeout.expired():
break
return bytes(line)
def iread_until(self, *args, **kwargs):
"""\
Read lines, implemented as generator. It will raise StopIteration on
timeout (empty read).
"""
while True:
line = self.read_until(*args, **kwargs)
if not line:
break
yield line
# - - - - - - - - - - - - - - - - - - - - - - - - -
if __name__ == '__main__':
import sys
s = SerialBase()
sys.stdout.write('port name: {}\n'.format(s.name))
sys.stdout.write('baud rates: {}\n'.format(s.BAUDRATES))
sys.stdout.write('byte sizes: {}\n'.format(s.BYTESIZES))
sys.stdout.write('parities: {}\n'.format(s.PARITIES))
sys.stdout.write('stop bits: {}\n'.format(s.STOPBITS))
sys.stdout.write('{}\n'.format(s))
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