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annotate Lib/ctypes/_endian.py @ 79675:c0a2294de787 2.7

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Issue #16199: Backport 2to3 typo fix from 3.2.
author Chris Jerdonek <chris.jerdonek@gmail.com>
date Thu, 11 Oct 2012 16:15:46 -0700
parents 7cdbf627f958
children
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381a72ab5fb8 Add pep-291 compatibility markers.
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1 ######################################################################
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2 # This file should be kept compatible with Python 2.3, see PEP 291. #
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3 ######################################################################
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4 import sys
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5 from ctypes import *
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6
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7cdbf627f958 Issue #12142: Fixed reference cycle when importing ctypes
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7 _array_type = type(Array)
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8
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9 def _other_endian(typ):
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10 """Return the type with the 'other' byte order. Simple types like
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11 c_int and so on already have __ctype_be__ and __ctype_le__
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12 attributes which contain the types, for more complicated types
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13 arrays and structures are supported.
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14 """
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15 # check _OTHER_ENDIAN attribute (present if typ is primitive type)
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16 if hasattr(typ, _OTHER_ENDIAN):
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17 return getattr(typ, _OTHER_ENDIAN)
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18 # if typ is array
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19 if isinstance(typ, _array_type):
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20 return _other_endian(typ._type_) * typ._length_
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21 # if typ is structure
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22 if issubclass(typ, Structure):
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23 return typ
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24 raise TypeError("This type does not support other endian: %s" % typ)
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25
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26 class _swapped_meta(type(Structure)):
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27 def __setattr__(self, attrname, value):
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28 if attrname == "_fields_":
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29 fields = []
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30 for desc in value:
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31 name = desc[0]
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32 typ = desc[1]
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33 rest = desc[2:]
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34 fields.append((name, _other_endian(typ)) + rest)
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35 value = fields
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36 super(_swapped_meta, self).__setattr__(attrname, value)
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37
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38 ################################################################
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39
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40 # Note: The Structure metaclass checks for the *presence* (not the
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41 # value!) of a _swapped_bytes_ attribute to determine the bit order in
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42 # structures containing bit fields.
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43
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44 if sys.byteorder == "little":
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45 _OTHER_ENDIAN = "__ctype_be__"
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46
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47 LittleEndianStructure = Structure
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48
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49 class BigEndianStructure(Structure):
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50 """Structure with big endian byte order"""
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51 __metaclass__ = _swapped_meta
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52 _swappedbytes_ = None
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53
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54 elif sys.byteorder == "big":
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55 _OTHER_ENDIAN = "__ctype_le__"
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56
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57 BigEndianStructure = Structure
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58 class LittleEndianStructure(Structure):
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59 """Structure with little endian byte order"""
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60 __metaclass__ = _swapped_meta
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61 _swappedbytes_ = None
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62
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63 else:
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64 raise RuntimeError("Invalid byteorder")