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# -*- coding: utf-8 -*-
#
# AWL simulator - utility functions
# Copyright 2012 Michael Buesch <m@bues.ch>
#
# Licensed under the terms of the GNU General Public License version 2.
#
import os
import random
import struct
class AwlSimError(Exception):
pass
class AwlParserError(Exception):
pass
def awlFileRead(filename):
try:
fd = open(filename, "r", encoding="latin_1")
data = fd.read()
fd.close()
except IOError as e:
raise AwlParserError("Failed to read '%s': %s" %\
(filename, str(e)))
return data
def awlFileWrite(filename, data):
data = "\r\n".join(data.splitlines()) + "\r\n"
for count in range(1000):
tmpFile = "%s-%d-%d.tmp" %\
(filename, random.randint(0, 0xFFFF), count)
if not os.path.exists(tmpFile):
break
else:
raise AwlParserError("Could not create temporary file")
try:
fd = open(tmpFile, "w", encoding="latin_1")
fd.write(data)
fd.flush()
fd.close()
if os.name.lower() != "posix":
# Can't use safe rename on non-POSIX.
# Must unlink first.
os.unlink(filename)
os.rename(tmpFile, filename)
except (IOError, OSError) as e:
raise AwlParserError("Failed to write file:\n" + str(e))
finally:
try:
os.unlink(tmpFile)
except (IOError, OSError):
pass
def byteToSignedPyInt(byte):
if byte & 0x80:
return -((~byte + 1) & 0xFF)
return byte & 0xFF
def wordToSignedPyInt(word):
if word & 0x8000:
return -((~word + 1) & 0xFFFF)
return word & 0xFFFF
def dwordToSignedPyInt(dword):
if dword & 0x80000000:
return -((~dword + 1) & 0xFFFFFFFF)
return dword & 0xFFFFFFFF
def pyFloatToDWord(pyfl):
buf = struct.pack('>f', pyfl)
dword = (buf[0] << 24) |\
(buf[1] << 16) |\
(buf[2] << 8) |\
buf[3]
if isDenormalPyFloat(pyfl):
# Denormal floats are equal to zero on the S7 CPU.
# OV and OS flags are set in the StatusWord handler.
dword = 0x00000000
elif (dword & 0x7FFFFFFF) > 0x7F800000:
# NaNs are always all-ones on the S7 CPU.
dword = 0xFFFFFFFF
return dword
def dwordToPyFloat(dword):
return struct.unpack('>f',
bytes( ((dword >> 24) & 0xFF,
(dword >> 16) & 0xFF,
(dword >> 8) & 0xFF,
dword & 0xFF)
)
)[0]
# The smallest normalized positive 32-bit float.
minNormPosFloat32 = dwordToPyFloat(0x00000001)
# The smallest normalized negative 32-bit float.
minNormNegFloat32 = dwordToPyFloat(0xFF7FFFFF)
# The biggest normalized negative 32-bit float.
maxNormNegFloat32 = dwordToPyFloat(0x80000001)
# The biggest normalized positive 32-bit float.
maxNormPosFloat32 = dwordToPyFloat(0x7F7FFFFF)
# Positive infinity as a python float
posInfFloat = dwordToPyFloat(0x7F800000)
# Negative infinity as a python float
negInfFloat = dwordToPyFloat(0xFF800000)
# NaN as a python float
nanFloat = dwordToPyFloat(0xFFFFFFFF)
def isDenormalPyFloat(pyfl):
return (pyfl > 0.0 and pyfl < minNormPosFloat32) or\
(pyfl < 0.0 and pyfl > maxNormNegFloat32)
def pyFloatEqual(pyfl0, pyfl1):
return abs(pyfl0 - pyfl1) < 0.000001
def floatEqual(fl0, fl1):
if not isinstance(fl0, float):
fl0 = dwordToPyFloat(fl0)
if not isinstance(fl1, float):
fl1 = dwordToPyFloat(fl1)
return pyFloatEqual(fl0, fl1)
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