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from __future__ import absolute_import

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import os

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import signal

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import subprocess

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import ctypes

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from threading import Thread

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import time

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import re

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import runtime.PLCObject as PLCObject

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from runtime.loglevels import LogLevelsDict

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SDOAnswered = PLCBinary.SDOAnswered

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SDOAnswered.restype = None

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SDOAnswered.argtypes = []

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SDOThread = None

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SDOProc = None

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Result = None

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def SDOThreadProc(*params):

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    global Result, SDOProc

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    if params[0] == "upload":

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        cmdfmt = "ethercat upload -p %d -t %s 0x%.4x 0x%.2x"

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    else:

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        cmdfmt = "ethercat download -p %d -t %s 0x%.4x 0x%.2x %s"

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    command = cmdfmt % params[1:]

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    SDOProc = subprocess.Popen(command, stdout=subprocess.PIPE, shell=True)

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    res = SDOProc.wait()

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    output = SDOProc.communicate()[0]

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    if params[0] == "upload":

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        Result = None

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        if res == 0:

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            if params[2] in ["float", "double"]:

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                Result = float(output)

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            elif params[2] in ["string", "octet_string", "unicode_string"]:

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                Result = output

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            else:

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                hex_value, dec_value = output.split()

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                if int(hex_value, 16) == int(dec_value):

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                    Result = int(dec_value)

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    else:

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        Result = res == 0

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    SDOAnswered()

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    if res != 0:

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        PLCObject.LogMessage(

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            LogLevelsDict["WARNING"],

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            "%s : %s" % (command, output))

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def EthercatSDOUpload(pos, index, subindex, var_type):

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    global SDOThread

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    SDOThread = Thread(target=SDOThreadProc, args=["upload", pos, var_type, index, subindex])

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    SDOThread.start()

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def EthercatSDODownload(pos, index, subindex, var_type, value):

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    global SDOThread

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    SDOThread = Thread(target=SDOThreadProc, args=["download", pos, var_type, index, subindex, value])

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    SDOThread.start()

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def GetResult():

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    return Result

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KMSGPollThread = None

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StopKMSGThread = False

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def KMSGPollThreadProc():

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    """

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    Logs Kernel messages starting with EtherCAT

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    Uses GLibc wrapper to Linux syscall "klogctl"

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    Last 4 KB are polled, and lines compared to last

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    captured line to detect new lines

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    """

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    libc = ctypes.CDLL("libc.so.6")

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    klog = libc.klogctl

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    klog.argtypes = [ctypes.c_int, ctypes.c_char_p, ctypes.c_int]

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    klog.restype = ctypes.c_int

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    s = ctypes.create_string_buffer(4*1024)

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    last = None

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    while not StopKMSGThread:

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        bytes_to_read = klog(3, s, len(s)-1)

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        log = s.value[:bytes_to_read-1]

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        if last:

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            log = log.rpartition(last)[2]

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        if log:

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            last = log.rpartition('\n')[2]

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            for lvl, msg in re.findall(

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                    r'<(\d)>\[\s*\d*\.\d*\]\s*(EtherCAT\s*.*)$',

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                    log, re.MULTILINE):

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                PLCObject.LogMessage(

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                    LogLevelsDict[{

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                        "4": "WARNING",

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                        "3": "CRITICAL"}.get(lvl, "DEBUG")],

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                    msg)

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        time.sleep(0.5)

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def _runtime_etherlab_init():

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    global KMSGPollThread, StopKMSGThread

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    StopKMSGThread = False

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    KMSGPollThread = Thread(target=KMSGPollThreadProc)

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    KMSGPollThread.start()

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def _runtime_etherlab_cleanup():

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    global KMSGPollThread, StopKMSGThread, SDOThread

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    try:

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        os.kill(SDOProc.pid, signal.SIGTERM)

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    except Exception:

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        pass

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    SDOThread = None

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    StopKMSGThread = True

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    KMSGPollThread = None