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gh-124351: Optimize Endianness Handling in ctypes Module #124355 #124407

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gh-124351: Optimize Endianness Handling in ctypes Module #124355 #124407

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17 changes: 5 additions & 12 deletions Lib/ctypes/_endian.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,9 @@
_array_type = type(Array)

def _other_endian(typ):
"""Return the type with the 'other' byte order. Simple types like
"""Return the type with the 'other' byte order. Simple types like
c_int and so on already have __ctype_be__ and __ctype_le__
attributes which contain the types, for more complicated types
attributes which contain the types; for more complicated types,
arrays and structures are supported.
"""
# check _OTHER_ENDIAN attribute (present if typ is primitive type)
Expand All @@ -18,19 +18,14 @@ def _other_endian(typ):
# if typ is structure or union
if issubclass(typ, (Structure, Union)):
return typ
raise TypeError("This type does not support other endian: %s" % typ)
raise TypeError(f"This type does not support other endian: {typ}")

class _swapped_meta:
def __setattr__(self, attrname, value):
if attrname == "_fields_":
fields = []
for desc in value:
name = desc[0]
typ = desc[1]
rest = desc[2:]
fields.append((name, _other_endian(typ)) + rest)
value = fields
value = [(desc[0], _other_endian(desc[1]), *desc[2:]) for desc in value]
super().__setattr__(attrname, value)

class _swapped_struct_meta(_swapped_meta, type(Structure)): pass
class _swapped_union_meta(_swapped_meta, type(Union)): pass

Expand All @@ -42,7 +37,6 @@ class _swapped_union_meta(_swapped_meta, type(Union)): pass

if sys.byteorder == "little":
_OTHER_ENDIAN = "__ctype_be__"

LittleEndianStructure = Structure

class BigEndianStructure(Structure, metaclass=_swapped_struct_meta):
Expand All @@ -59,7 +53,6 @@ class BigEndianUnion(Union, metaclass=_swapped_union_meta):

elif sys.byteorder == "big":
_OTHER_ENDIAN = "__ctype_le__"

BigEndianStructure = Structure

class LittleEndianStructure(Structure, metaclass=_swapped_struct_meta):
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