New issue 2066: ctypes.BigEndianStructure does not appear to swap byte order on
PyPy
https://bitbucket.org/pypy/pypy/issue/2066/ctypesbigendianstructure-does-not-appear
David Wilson:
When run on a little endian machine, the output of the following script differs
between CPython and PyPy:
````
import sys
import ctypes
FIELDS = [
('n', ctypes.c_uint16)
]
class Native(ctypes.Structure):
_fields_ = FIELDS
class Big(ctypes.BigEndianStructure):
_fields_ = FIELDS
class Little(ctypes.LittleEndianStructure):
_fields_ = FIELDS
def dostruct(c):
ba = ctypes.create_string_buffer(ctypes.sizeof(c))
ms = c.from_buffer(ba)
ms.n = 0xff00
return repr(ba[:])
print 'Native', dostruct(Native)
print 'Big', dostruct(Big)
print 'Little', dostruct(Little)
if sys.byteorder == 'little':
assert dostruct(Native) == dostruct(Little)
elif sys.byteorder == 'big':
assert dostruct(Native) == dostruct(Big)
else:
assert 0, 'typo'
````
On CPython, we see that the byte order of `Big` is swapped:
````
python p2.py
Native '\x00\xff'
Big '\xff\x00'
Little '\x00\xff'
````
Whereas on PyPy 2.6.0 it is not the case:
````
Native '\x00\xff'
Big '\x00\xff'
Little '\x00\xff'
````
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