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Parity-Bit cleanup
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@arnegue
arnegue committed Apr 23, 2024
1 parent e08b5e4 commit 777aac3
Showing 1 changed file with 15 additions and 250 deletions.
265 changes: 15 additions & 250 deletions common/parity_serial.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,9 +7,8 @@
import ctypes

else:
from serial.serialposix import Serial, SerialException, CMSPAR
from serial.serialposix import Serial, SerialException
import termios
import fcntl


class ParityException(SerialException):
Expand All @@ -19,301 +18,67 @@ class ParityException(SerialException):
class WinParitySerial(Serial):
"""
This is nearly the same as the Windows implementation. The only difference is setting the (f)ErrorChar in _reconfigure_port
Raises ParityError on Read
"""
def __init__(self, *args, **kwargs):
self.parity_replace_char = 0xFE
self.parity_replace_byte = bytes([self.parity_replace_char])
super().__init__(*args, **kwargs)

def _reconfigure_port(self):
"""Set communication parameters on opened port."""
if not self._port_handle:
raise SerialException("Can only operate on a valid port handle")

# Set Windows timeout values
# timeouts is a tuple with the following items:
# (ReadIntervalTimeout,ReadTotalTimeoutMultiplier,
# ReadTotalTimeoutConstant,WriteTotalTimeoutMultiplier,
# WriteTotalTimeoutConstant)
timeouts = win32.COMMTIMEOUTS()
if self._timeout is None:
pass # default of all zeros is OK
elif self._timeout == 0:
timeouts.ReadIntervalTimeout = win32.MAXDWORD
else:
timeouts.ReadTotalTimeoutConstant = max(int(self._timeout * 1000), 1)
if self._timeout != 0 and self._inter_byte_timeout is not None:
timeouts.ReadIntervalTimeout = max(int(self._inter_byte_timeout * 1000), 1)

if self._write_timeout is None:
pass
elif self._write_timeout == 0:
timeouts.WriteTotalTimeoutConstant = win32.MAXDWORD
else:
timeouts.WriteTotalTimeoutConstant = max(int(self._write_timeout * 1000), 1)
win32.SetCommTimeouts(self._port_handle, ctypes.byref(timeouts))

win32.SetCommMask(self._port_handle, win32.EV_ERR)

# Setup the connection info.
super()._reconfigure_port()
# Get state and modify it:
comDCB = win32.DCB()
win32.GetCommState(self._port_handle, ctypes.byref(comDCB))
comDCB.BaudRate = self._baudrate

if self._bytesize == serial.FIVEBITS:
comDCB.ByteSize = 5
elif self._bytesize == serial.SIXBITS:
comDCB.ByteSize = 6
elif self._bytesize == serial.SEVENBITS:
comDCB.ByteSize = 7
elif self._bytesize == serial.EIGHTBITS:
comDCB.ByteSize = 8
else:
raise ValueError("Unsupported number of data bits: {!r}".format(self._bytesize))

if self._parity == serial.PARITY_NONE:
comDCB.Parity = win32.NOPARITY
comDCB.fParity = 0 # Disable Parity Check
elif self._parity == serial.PARITY_EVEN:
comDCB.Parity = win32.EVENPARITY
comDCB.fParity = 1 # Enable Parity Check
elif self._parity == serial.PARITY_ODD:
comDCB.Parity = win32.ODDPARITY
comDCB.fParity = 1 # Enable Parity Check
elif self._parity == serial.PARITY_MARK:
comDCB.Parity = win32.MARKPARITY
comDCB.fParity = 1 # Enable Parity Check
elif self._parity == serial.PARITY_SPACE:
comDCB.Parity = win32.SPACEPARITY
comDCB.fParity = 1 # Enable Parity Check
else:
raise ValueError("Unsupported parity mode: {!r}".format(self._parity))

if self._stopbits == serial.STOPBITS_ONE:
comDCB.StopBits = win32.ONESTOPBIT
elif self._stopbits == serial.STOPBITS_ONE_POINT_FIVE:
comDCB.StopBits = win32.ONE5STOPBITS
elif self._stopbits == serial.STOPBITS_TWO:
comDCB.StopBits = win32.TWOSTOPBITS
else:
raise ValueError("Unsupported number of stop bits: {!r}".format(self._stopbits))

comDCB.fBinary = 1 # Enable Binary Transmission
# Char. w/ Parity-Err are replaced with 0xff (if fErrorChar is set to TRUE)
if self._rs485_mode is None:
if self._rtscts:
comDCB.fRtsControl = win32.RTS_CONTROL_HANDSHAKE
else:
comDCB.fRtsControl = win32.RTS_CONTROL_ENABLE if self._rts_state else win32.RTS_CONTROL_DISABLE
comDCB.fOutxCtsFlow = self._rtscts
else:
# checks for unsupported settings
# XXX verify if platform really does not have a setting for those
if not self._rs485_mode.rts_level_for_tx:
raise ValueError(
'Unsupported value for RS485Settings.rts_level_for_tx: {!r}'.format(
self._rs485_mode.rts_level_for_tx,))
if self._rs485_mode.rts_level_for_rx:
raise ValueError(
'Unsupported value for RS485Settings.rts_level_for_rx: {!r}'.format(
self._rs485_mode.rts_level_for_rx,))
if self._rs485_mode.delay_before_tx is not None:
raise ValueError(
'Unsupported value for RS485Settings.delay_before_tx: {!r}'.format(
self._rs485_mode.delay_before_tx,))
if self._rs485_mode.delay_before_rx is not None:
raise ValueError(
'Unsupported value for RS485Settings.delay_before_rx: {!r}'.format(
self._rs485_mode.delay_before_rx,))
if self._rs485_mode.loopback:
raise ValueError(
'Unsupported value for RS485Settings.loopback: {!r}'.format(
self._rs485_mode.loopback,))
comDCB.fRtsControl = win32.RTS_CONTROL_TOGGLE
comDCB.fOutxCtsFlow = 0

if self._dsrdtr:
comDCB.fDtrControl = win32.DTR_CONTROL_HANDSHAKE
else:
comDCB.fDtrControl = win32.DTR_CONTROL_ENABLE if self._dtr_state else win32.DTR_CONTROL_DISABLE
comDCB.fOutxDsrFlow = self._dsrdtr
comDCB.fOutX = self._xonxoff
comDCB.fInX = self._xonxoff
comDCB.fNull = 0

# DIFFERENCE TO pyserial's implementation
comDCB.fErrorChar = 1 # Enable error char
comDCB.ErrorChar = self.parity_replace_char

comDCB.fAbortOnError = 0
comDCB.XonChar = serial.XON
comDCB.XoffChar = serial.XOFF

if not win32.SetCommState(self._port_handle, ctypes.byref(comDCB)):
raise SerialException(
'Cannot configure port, something went wrong. '
'Original message: {!r}'.format(ctypes.WinError()))

def read(self, *args, **kwargs):
read_byte = super().read(*args, **kwargs)
def read(self, size=1):
"""
Reads bytes, if parity_replace_char was received, raises ParityError
"""
read_byte = super().read(size)
if read_byte == self.parity_replace_byte:
raise ParityException()
return read_byte


class LinuxParitySerial(Serial):
"""
Nearly the same as PosixSerial, but enables PARMRK and INPCK
Nearly the same as PosixSerial, but enables PARMRK and INPCK.
Raises ParityError on Read
"""
PARITY_BYTES = [bytes([0xFF, ]), bytes([0x00, ])] # Bytes of a parity error (see termios' PARMRK)

def _reconfigure_port(self, force_update=False):
if self.fd is None:
raise SerialException("Can only operate on a valid file descriptor")

# if exclusive lock is requested, create it before we modify anything else
if self._exclusive is not None:
if self._exclusive:
try:
fcntl.flock(self.fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError as msg:
raise SerialException(msg.errno, "Could not exclusively lock port {}: {}".format(self._port, msg))
else:
fcntl.flock(self.fd, fcntl.LOCK_UN)

custom_baud = None
super()._reconfigure_port(force_update=force_update)

vmin = vtime = 0 # timeout is done via select
if self._inter_byte_timeout is not None:
vmin = 1
vtime = int(self._inter_byte_timeout * 10)
try:
orig_attr = termios.tcgetattr(self.fd)
iflag, oflag, cflag, lflag, ispeed, ospeed, cc = orig_attr
except termios.error as msg: # if a port is nonexistent but has a /dev file, it'll fail here
raise SerialException("Could not configure port: {}".format(msg))
# set up raw mode / no echo / binary
cflag |= (termios.CLOCAL | termios.CREAD)
lflag &= ~(termios.ICANON | termios.ECHO | termios.ECHOE |
termios.ECHOK | termios.ECHONL |
termios.ISIG | termios.IEXTEN) # |termios.ECHOPRT
for flag in ('ECHOCTL', 'ECHOKE'): # netbsd workaround for Erk
if hasattr(termios, flag):
lflag &= ~getattr(termios, flag)

oflag &= ~(termios.OPOST | termios.ONLCR | termios.OCRNL)
iflag &= ~(termios.INLCR | termios.IGNCR | termios.ICRNL | termios.IGNBRK)
if hasattr(termios, 'IUCLC'):
iflag &= ~termios.IUCLC

# DIFFERENCE TO pyserial's implementation
iflag |= termios.PARMRK | termios.INPCK

# setup baud rate
try:
ispeed = ospeed = getattr(termios, 'B{}'.format(self._baudrate))
except AttributeError:
try:
ispeed = ospeed = self.BAUDRATE_CONSTANTS[self._baudrate]
except KeyError:
#~ raise ValueError('Invalid baud rate: %r' % self._baudrate)
# may need custom baud rate, it isn't in our list.
ispeed = ospeed = getattr(termios, 'B38400')
try:
custom_baud = int(self._baudrate) # store for later
except ValueError:
raise ValueError('Invalid baud rate: {!r}'.format(self._baudrate))
else:
if custom_baud < 0:
raise ValueError('Invalid baud rate: {!r}'.format(self._baudrate))

# setup char len
cflag &= ~termios.CSIZE
if self._bytesize == 8:
cflag |= termios.CS8
elif self._bytesize == 7:
cflag |= termios.CS7
elif self._bytesize == 6:
cflag |= termios.CS6
elif self._bytesize == 5:
cflag |= termios.CS5
else:
raise ValueError('Invalid char len: {!r}'.format(self._bytesize))
# setup stop bits
if self._stopbits == serial.STOPBITS_ONE:
cflag &= ~(termios.CSTOPB)
elif self._stopbits == serial.STOPBITS_ONE_POINT_FIVE:
cflag |= (termios.CSTOPB) # XXX same as TWO.. there is no POSIX support for 1.5
elif self._stopbits == serial.STOPBITS_TWO:
cflag |= (termios.CSTOPB)
else:
raise ValueError('Invalid stop bit specification: {!r}'.format(self._stopbits))
# setup parity
iflag &= ~(termios.ISTRIP)
if self._parity == serial.PARITY_NONE:
cflag &= ~(termios.PARENB | termios.PARODD | CMSPAR)
elif self._parity == serial.PARITY_EVEN:
cflag &= ~(termios.PARODD | CMSPAR)
cflag |= (termios.PARENB)
elif self._parity == serial.PARITY_ODD:
cflag &= ~CMSPAR
cflag |= (termios.PARENB | termios.PARODD)
elif self._parity == serial.PARITY_MARK and CMSPAR:
cflag |= (termios.PARENB | CMSPAR | termios.PARODD)
elif self._parity == serial.PARITY_SPACE and CMSPAR:
cflag |= (termios.PARENB | CMSPAR)
cflag &= ~(termios.PARODD)
else:
raise ValueError('Invalid parity: {!r}'.format(self._parity))
# setup flow control
# xonxoff
if hasattr(termios, 'IXANY'):
if self._xonxoff:
iflag |= (termios.IXON | termios.IXOFF) # |termios.IXANY)
else:
iflag &= ~(termios.IXON | termios.IXOFF | termios.IXANY)
else:
if self._xonxoff:
iflag |= (termios.IXON | termios.IXOFF)
else:
iflag &= ~(termios.IXON | termios.IXOFF)
# rtscts
if hasattr(termios, 'CRTSCTS'):
if self._rtscts:
cflag |= (termios.CRTSCTS)
else:
cflag &= ~(termios.CRTSCTS)
elif hasattr(termios, 'CNEW_RTSCTS'): # try it with alternate constant name
if self._rtscts:
cflag |= (termios.CNEW_RTSCTS)
else:
cflag &= ~(termios.CNEW_RTSCTS)
# XXX should there be a warning if setting up rtscts (and xonxoff etc) fails??

# buffer
# vmin "minimal number of characters to be read. 0 for non blocking"
if vmin < 0 or vmin > 255:
raise ValueError('Invalid vmin: {!r}'.format(vmin))
cc[termios.VMIN] = vmin
# vtime
if vtime < 0 or vtime > 255:
raise ValueError('Invalid vtime: {!r}'.format(vtime))
cc[termios.VTIME] = vtime
# activate settings
if force_update or [iflag, oflag, cflag, lflag, ispeed, ospeed, cc] != orig_attr:
termios.tcsetattr(
self.fd,
termios.TCSANOW,
[iflag, oflag, cflag, lflag, ispeed, ospeed, cc])

# apply custom baud rate, if any
if custom_baud is not None:
self._set_special_baudrate(custom_baud)

if self._rs485_mode is not None:
self._set_rs485_mode(self._rs485_mode)

def read(self, size=1):
"""
Reads bytes, if PARITY_BYTES were received, raises ParityError
"""
if size != 1:
raise AttributeError("Reading more than 1 byte not supported")
if not hasattr(self, "last_byte"):
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