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#! python
#
# backend for Windows ("win32" incl. 32/64 bit support)
#
# (C) 2001-2020 Chris Liechti <cliechti@gmx.net>
#
# This file is part of pySerial. https://github.com/pyserial/pyserial
# SPDX-License-Identifier: BSD-3-Clause
#
# Initial patch to use ctypes by Giovanni Bajo <rasky@develer.com>
from __future__ import absolute_import
# pylint: disable=invalid-name,too-few-public-methods
import ctypes
import time
from serial import win32
import serial
from serial.serialutil import SerialBase, SerialException, to_bytes, PortNotOpenError, SerialTimeoutException
class Serial(SerialBase):
"""Serial port implementation for Win32 based on ctypes."""
BAUDRATES = (50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
9600, 19200, 38400, 57600, 115200)
def __init__(self, *args, **kwargs):
self._port_handle = None
self._overlapped_read = None
self._overlapped_write = None
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._port is None:
raise SerialException("Port must be configured before it can be used.")
if self.is_open:
raise SerialException("Port is already open.")
# the "\\.\COMx" format is required for devices other than COM1-COM8
# not all versions of windows seem to support this properly
# so that the first few ports are used with the DOS device name
port = self.name
try:
if port.upper().startswith('COM') and int(port[3:]) > 8:
port = '\\\\.\\' + port
except ValueError:
# for like COMnotanumber
pass
self._port_handle = win32.CreateFile(
port,
win32.GENERIC_READ | win32.GENERIC_WRITE,
0, # exclusive access
None, # no security
win32.OPEN_EXISTING,
win32.FILE_ATTRIBUTE_NORMAL | win32.FILE_FLAG_OVERLAPPED,
0)
if self._port_handle == win32.INVALID_HANDLE_VALUE:
self._port_handle = None # 'cause __del__ is called anyway
raise SerialException("could not open port {!r}: {!r}".format(self.portstr, ctypes.WinError()))
try:
self._overlapped_read = win32.OVERLAPPED()
self._overlapped_read.hEvent = win32.CreateEvent(None, 1, 0, None)
self._overlapped_write = win32.OVERLAPPED()
#~ self._overlapped_write.hEvent = win32.CreateEvent(None, 1, 0, None)
self._overlapped_write.hEvent = win32.CreateEvent(None, 0, 0, None)
# Setup a 4k buffer
win32.SetupComm(self._port_handle, 4096, 4096)
# Save original timeout values:
self._orgTimeouts = win32.COMMTIMEOUTS()
win32.GetCommTimeouts(self._port_handle, ctypes.byref(self._orgTimeouts))
self._reconfigure_port()
# Clear buffers:
# Remove anything that was there
win32.PurgeComm(
self._port_handle,
win32.PURGE_TXCLEAR | win32.PURGE_TXABORT |
win32.PURGE_RXCLEAR | win32.PURGE_RXABORT)
except:
try:
self._close()
except:
# ignore any exception when closing the port
# also to keep original exception that happened when setting up
pass
self._port_handle = None
raise
else:
self.is_open = True
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.
# 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} (only True is allowed)'.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} (only False is allowed)'.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} (only None is allowed)'.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} (only None is allowed)'.format(
self._rs485_mode.delay_before_rx,))
if self._rs485_mode.loopback:
raise ValueError(
'Unsupported value for RS485Settings.loopback: {!r} (only False is allowed)'.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
comDCB.fErrorChar = 0
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 __del__(self):
#~ self.close()
def _close(self):
"""internal close port helper"""
if self._port_handle is not None:
# Restore original timeout values:
win32.SetCommTimeouts(self._port_handle, self._orgTimeouts)
if self._overlapped_read is not None:
self.cancel_read()
win32.CloseHandle(self._overlapped_read.hEvent)
self._overlapped_read = None
if self._overlapped_write is not None:
self.cancel_write()
win32.CloseHandle(self._overlapped_write.hEvent)
self._overlapped_write = None
win32.CloseHandle(self._port_handle)
self._port_handle = None
def close(self):
"""Close port"""
if self.is_open:
self._close()
self.is_open = False
# - - - - - - - - - - - - - - - - - - - - - - - -
@property
def in_waiting(self):
"""Return the number of bytes currently in the input buffer."""
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()))
return comstat.cbInQue
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)
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 SerialTimeoutException('Write timeout')
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 flush(self):
"""\
Flush of file like objects. In this case, wait until all data
is written.
"""
while self.out_waiting:
time.sleep(0.05)
# XXX could also use WaitCommEvent with mask EV_TXEMPTY, but it would
# require overlapped IO and it's also only possible to set a single mask
# on the port---
def reset_input_buffer(self):
"""Clear input buffer, discarding all that is in the buffer."""
if not self.is_open:
raise PortNotOpenError()
win32.PurgeComm(self._port_handle, win32.PURGE_RXCLEAR | win32.PURGE_RXABORT)
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()
win32.PurgeComm(self._port_handle, win32.PURGE_TXCLEAR | win32.PURGE_TXABORT)
def _update_break_state(self):
"""Set break: Controls TXD. When active, to transmitting is possible."""
if not self.is_open:
raise PortNotOpenError()
if self._break_state:
win32.SetCommBreak(self._port_handle)
else:
win32.ClearCommBreak(self._port_handle)
def _update_rts_state(self):
"""Set terminal status line: Request To Send"""
if self._rts_state:
win32.EscapeCommFunction(self._port_handle, win32.SETRTS)
else:
win32.EscapeCommFunction(self._port_handle, win32.CLRRTS)
def _update_dtr_state(self):
"""Set terminal status line: Data Terminal Ready"""
if self._dtr_state:
win32.EscapeCommFunction(self._port_handle, win32.SETDTR)
else:
win32.EscapeCommFunction(self._port_handle, win32.CLRDTR)
def _GetCommModemStatus(self):
if not self.is_open:
raise PortNotOpenError()
stat = win32.DWORD()
win32.GetCommModemStatus(self._port_handle, ctypes.byref(stat))
return stat.value
@property
def cts(self):
"""Read terminal status line: Clear To Send"""
return win32.MS_CTS_ON & self._GetCommModemStatus() != 0
@property
def dsr(self):
"""Read terminal status line: Data Set Ready"""
return win32.MS_DSR_ON & self._GetCommModemStatus() != 0
@property
def ri(self):
"""Read terminal status line: Ring Indicator"""
return win32.MS_RING_ON & self._GetCommModemStatus() != 0
@property
def cd(self):
"""Read terminal status line: Carrier Detect"""
return win32.MS_RLSD_ON & self._GetCommModemStatus() != 0
# - - platform specific - - - -
def set_buffer_size(self, rx_size=4096, tx_size=None):
"""\
Recommend a buffer size to the driver (device driver can ignore this
value). Must be called after the port is opened.
"""
if tx_size is None:
tx_size = rx_size
win32.SetupComm(self._port_handle, rx_size, tx_size)
def set_output_flow_control(self, enable=True):
"""\
Manually control flow - when software flow control is enabled.
This will do the same as if XON (true) or XOFF (false) are received
from the other device and control the transmission accordingly.
WARNING: this function is not portable to different platforms!
"""
if not self.is_open:
raise PortNotOpenError()
if enable:
win32.EscapeCommFunction(self._port_handle, win32.SETXON)
else:
win32.EscapeCommFunction(self._port_handle, win32.SETXOFF)
@property
def out_waiting(self):
"""Return how many bytes the in the outgoing buffer"""
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()))
return comstat.cbOutQue
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 cancel_read(self):
"""Cancel a blocking read operation, may be called from other thread"""
self._cancel_overlapped_io(self._overlapped_read)
def cancel_write(self):
"""Cancel a blocking write operation, may be called from other thread"""
self._cancel_overlapped_io(self._overlapped_write)
@SerialBase.exclusive.setter
def exclusive(self, exclusive):
"""Change the exclusive access setting."""
if exclusive is not None and not exclusive:
raise ValueError('win32 only supports exclusive access (not: {})'.format(exclusive))
else:
serial.SerialBase.exclusive.__set__(self, exclusive)
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