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Created on 2017-11-08 22:31 by mleroy003, last changed 2022-04-11 14:58 by admin. This issue is now closed.
| Messages (2) | |||
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| msg305914 - (view) | Author: Marc Le Roy (mleroy003) | Date: 2017-11-08 22:31 | |
The structure :
typedef struct __attribute__ ((packed)) {
unsigned int F0:24;
unsigned int F3:24;
unsigned int F6:24;
unsigned int F9:24;
} StructF_T;
is mapped as expected by GCC under both Linux and Cygwin.
As expected, the memory layout seen by the C program is :
0x111111222222333333444444
Using this definition :
class StructF(ctypes.BigEndianStructure):
_pack_ = 1
_fields_ = [
('F0', ctypes.c_uint, 24),
('F3', ctypes.c_uint, 24),
('F6', ctypes.c_uint, 24),
('F9', ctypes.c_uint, 24),
]
The memory layout seen from Python is not consistent :
0x11111100222222003333330044444400
It seems that the pack option is ignored by ctypes in such a case.
I found the same problem using both ctypes.BigEndianStructure and ctypes.LittleEndianStructure
|
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| msg305957 - (view) | Author: Berker Peksag (berker.peksag) *  |
Date: 2017-11-09 11:39 | |
Thank you for your report. I believe this is a duplicate of issue 29753. |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:58:54 | admin | set | github: 76168 |
| 2017-11-09 11:39:58 | berker.peksag | set | status: open -> closed superseder: [Linux] ctypes packs bitfields Incorrectly type: behavior nosy: + berker.peksag messages: + msg305957 resolution: duplicate stage: resolved |
| 2017-11-08 22:31:58 | mleroy003 | create | |