242 lines
6.3 KiB
Python
242 lines
6.3 KiB
Python
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# Copyright 2017 The Chromium OS Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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"""Allow creation of uart/console interface via stm32 usb endpoint."""
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from __future__ import print_function
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import os
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import select
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import sys
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import termios
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import threading
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import time
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import tty
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import usb
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import stm32usb
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class SuartError(Exception):
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"""Class for exceptions of Suart."""
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def __init__(self, msg, value=0):
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"""SuartError constructor.
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Args:
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msg: string, message describing error in detail
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value: integer, value of error when non-zero status returned. Default=0
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"""
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super(SuartError, self).__init__(msg, value)
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self.msg = msg
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self.value = value
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class Suart(object):
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"""Provide interface to stm32 serial usb endpoint."""
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def __init__(self, vendor=0x18d1, product=0x501a, interface=0,
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serialname=None, debuglog=False):
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"""Suart contstructor.
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Initializes stm32 USB stream interface.
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Args:
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vendor: usb vendor id of stm32 device
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product: usb product id of stm32 device
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interface: interface number of stm32 device to use
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serialname: serial name to target. Defaults to None.
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debuglog: chatty output. Defaults to False.
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Raises:
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SuartError: If init fails
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"""
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self._ptym = None
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self._ptys = None
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self._ptyname = None
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self._rx_thread = None
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self._tx_thread = None
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self._debuglog = debuglog
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self._susb = stm32usb.Susb(vendor=vendor, product=product,
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interface=interface, serialname=serialname)
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self._running = False
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def __del__(self):
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"""Suart destructor."""
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self.close()
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def close(self):
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"""Stop all running threads."""
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self._running = False
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if self._rx_thread:
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self._rx_thread.join(2)
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self._rx_thread = None
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if self._tx_thread:
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self._tx_thread.join(2)
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self._tx_thread = None
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self._susb.close()
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def run_rx_thread(self):
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"""Background loop to pass data from USB to pty."""
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ep = select.epoll()
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ep.register(self._ptym, select.EPOLLHUP)
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try:
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while self._running:
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events = ep.poll(0)
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# Check if the pty is connected to anything, or hungup.
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if not events:
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try:
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r = self._susb._read_ep.read(64, self._susb.TIMEOUT_MS)
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if r:
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if self._debuglog:
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print(''.join([chr(x) for x in r]), end='')
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os.write(self._ptym, r)
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# If we miss some characters on pty disconnect, that's fine.
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# ep.read() also throws USBError on timeout, which we discard.
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except OSError:
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pass
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except usb.core.USBError:
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pass
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else:
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time.sleep(.1)
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except Exception as e:
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raise e
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def run_tx_thread(self):
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"""Background loop to pass data from pty to USB."""
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ep = select.epoll()
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ep.register(self._ptym, select.EPOLLHUP)
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try:
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while self._running:
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events = ep.poll(0)
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# Check if the pty is connected to anything, or hungup.
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if not events:
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try:
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r = os.read(self._ptym, 64)
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if r:
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self._susb._write_ep.write(r, self._susb.TIMEOUT_MS)
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except OSError:
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pass
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except usb.core.USBError:
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pass
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else:
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time.sleep(.1)
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except Exception as e:
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raise e
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def run(self):
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"""Creates pthreads to poll stm32 & PTY for data."""
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m, s = os.openpty()
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self._ptyname = os.ttyname(s)
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self._ptym = m
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self._ptys = s
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os.fchmod(s, 0o660)
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# Change the owner and group of the PTY to the user who started servod.
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try:
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uid = int(os.environ.get('SUDO_UID', -1))
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except TypeError:
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uid = -1
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try:
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gid = int(os.environ.get('SUDO_GID', -1))
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except TypeError:
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gid = -1
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os.fchown(s, uid, gid)
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tty.setraw(self._ptym, termios.TCSADRAIN)
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# Generate a HUP flag on pty slave fd.
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os.fdopen(s).close()
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self._running = True
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self._rx_thread = threading.Thread(target=self.run_rx_thread, args=[])
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self._rx_thread.daemon = True
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self._rx_thread.start()
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self._tx_thread = threading.Thread(target=self.run_tx_thread, args=[])
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self._tx_thread.daemon = True
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self._tx_thread.start()
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def get_uart_props(self):
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"""Get the uart's properties.
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Returns:
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dict where:
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baudrate: integer of uarts baudrate
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bits: integer, number of bits of data Can be 5|6|7|8 inclusive
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parity: integer, parity of 0-2 inclusive where:
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0: no parity
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1: odd parity
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2: even parity
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sbits: integer, number of stop bits. Can be 0|1|2 inclusive where:
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0: 1 stop bit
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1: 1.5 stop bits
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2: 2 stop bits
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"""
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return {
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'baudrate': 115200,
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'bits': 8,
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'parity': 0,
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'sbits': 1,
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}
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def set_uart_props(self, line_props):
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"""Set the uart's properties.
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Note that Suart cannot set properties
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and will fail if the properties are not the default 115200,8n1.
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Args:
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line_props: dict where:
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baudrate: integer of uarts baudrate
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bits: integer, number of bits of data ( prior to stop bit)
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parity: integer, parity of 0-2 inclusive where
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0: no parity
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1: odd parity
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2: even parity
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sbits: integer, number of stop bits. Can be 0|1|2 inclusive where:
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0: 1 stop bit
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1: 1.5 stop bits
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2: 2 stop bits
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Raises:
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SuartError: If requested line properties are not the default.
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"""
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curr_props = self.get_uart_props()
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for prop in line_props:
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if line_props[prop] != curr_props[prop]:
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raise SuartError('Line property %s cannot be set from %s to %s' % (
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prop, curr_props[prop], line_props[prop]))
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return True
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def get_pty(self):
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"""Gets path to pty for communication to/from uart.
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Returns:
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String path to the pty connected to the uart
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"""
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return self._ptyname
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def main():
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"""Run a suart test with the default parameters."""
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try:
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sobj = Suart()
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sobj.run()
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# run() is a thread so just busy wait to mimic server.
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while True:
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# Ours sleeps to eleven!
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time.sleep(11)
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except KeyboardInterrupt:
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sys.exit(0)
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if __name__ == '__main__':
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main()
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