New submission from Steve Thompson <steve.f.thomp...@gmail.com>:
Consider the following:
import ctypes
class struct1( ctypes.Structure ):
_pack_ = 1
_fields_ = [
( "first", ctypes.c_uint8, 1 ),
( "second", ctypes.c_uint8, 1 ),
( "third", ctypes.c_uint8, 1 ),
( "fourth", ctypes.c_uint8, 1 ),
( "fifth", ctypes.c_uint8, 1 ),
( "pad", ctypes.c_uint16, 11 ),
]
s1 = struct1()
print ctypes.sizeof( s1 )
class struct2( ctypes.Structure ):
_pack_ = 1
_fields_ = [
( "first", ctypes.c_uint16, 1 ),
( "second", ctypes.c_uint16, 1 ),
( "third", ctypes.c_uint16, 1 ),
( "fourth", ctypes.c_uint16, 1 ),
( "fifth", ctypes.c_uint16, 1 ),
( "pad", ctypes.c_uint16, 11 ),
]
s2 = struct2()
print ctypes.sizeof( s2 )
The output is:
3
2
I'm generating python code from real c code. The compiler I'm using for the
real c code packs both of these structures into two bytes. I need a way to
make the first example work in python like the compiler without having to
modify the source code.
Is this possible?
----------
components: ctypes
messages: 134393
nosy: Steve.Thompson
priority: normal
severity: normal
status: open
title: ctypes: Strange bitfield structure sizing issue
versions: Python 2.6
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue11920>
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