1  import sys
       2  from ctypes import *
       3  
       4  _array_type = type(Array)
       5  
       6  def _other_endian(typ):
       7      """Return the type with the 'other' byte order.  Simple types like
       8      c_int and so on already have __ctype_be__ and __ctype_le__
       9      attributes which contain the types, for more complicated types
      10      arrays and structures are supported.
      11      """
      12      # check _OTHER_ENDIAN attribute (present if typ is primitive type)
      13      if hasattr(typ, _OTHER_ENDIAN):
      14          return getattr(typ, _OTHER_ENDIAN)
      15      # if typ is array
      16      if isinstance(typ, _array_type):
      17          return _other_endian(typ._type_) * typ._length_
      18      # if typ is structure
      19      if issubclass(typ, Structure):
      20          return typ
      21      raise TypeError("This type does not support other endian: %s" % typ)
      22  
      23  class ESC[4;38;5;81m_swapped_meta:
      24      def __setattr__(self, attrname, value):
      25          if attrname == "_fields_":
      26              fields = []
      27              for desc in value:
      28                  name = desc[0]
      29                  typ = desc[1]
      30                  rest = desc[2:]
      31                  fields.append((name, _other_endian(typ)) + rest)
      32              value = fields
      33          super().__setattr__(attrname, value)
      34  class ESC[4;38;5;81m_swapped_struct_meta(ESC[4;38;5;149m_swapped_meta, ESC[4;38;5;149mtype(Structure)): pass
      35  class ESC[4;38;5;81m_swapped_union_meta(ESC[4;38;5;149m_swapped_meta, ESC[4;38;5;149mtype(Union)): pass
      36  
      37  ################################################################
      38  
      39  # Note: The Structure metaclass checks for the *presence* (not the
      40  # value!) of a _swapped_bytes_ attribute to determine the bit order in
      41  # structures containing bit fields.
      42  
      43  if sys.byteorder == "little":
      44      _OTHER_ENDIAN = "__ctype_be__"
      45  
      46      LittleEndianStructure = Structure
      47  
      48      class ESC[4;38;5;81mBigEndianStructure(ESC[4;38;5;149mStructure, metaclass=ESC[4;38;5;149m_swapped_struct_meta):
      49          """Structure with big endian byte order"""
      50          __slots__ = ()
      51          _swappedbytes_ = None
      52  
      53      LittleEndianUnion = Union
      54  
      55      class ESC[4;38;5;81mBigEndianUnion(ESC[4;38;5;149mUnion, metaclass=ESC[4;38;5;149m_swapped_union_meta):
      56          """Union with big endian byte order"""
      57          __slots__ = ()
      58          _swappedbytes_ = None
      59  
      60  elif sys.byteorder == "big":
      61      _OTHER_ENDIAN = "__ctype_le__"
      62  
      63      BigEndianStructure = Structure
      64  
      65      class ESC[4;38;5;81mLittleEndianStructure(ESC[4;38;5;149mStructure, metaclass=ESC[4;38;5;149m_swapped_struct_meta):
      66          """Structure with little endian byte order"""
      67          __slots__ = ()
      68          _swappedbytes_ = None
      69  
      70      BigEndianUnion = Union
      71  
      72      class ESC[4;38;5;81mLittleEndianUnion(ESC[4;38;5;149mUnion, metaclass=ESC[4;38;5;149m_swapped_union_meta):
      73          """Union with little endian byte order"""
      74          __slots__ = ()
      75          _swappedbytes_ = None
      76  
      77  else:
      78      raise RuntimeError("Invalid byteorder")