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Created on 2015-05-26 19:02 by Rony Batista, last changed 2022-04-11 14:58 by admin.
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| File name | Uploaded | Description | Edit | |
| ctypesBug.py | Rony Batista, 2015-05-26 19:06 | |||
| Messages (5) | |||
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| msg244125 - (view) | Author: Rony Batista (Rony Batista) | Date: 2015-05-26 19:02 | |
ctypes Structures with c_uint32 bitfields have strange behaviour on OS X. In the attached code when the field "number" is set, it changes the whole 32 bits, even thou its meant to be 23 bits. The behavior is unexpected in: OS X: Python 2.7.9 The behavior is as expected in the following environments: Windows: python 2.7.9 Ubuntu: python 2.7.6 |
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| msg244126 - (view) | Author: Ronald Oussoren (ronaldoussoren) *  |
Date: 2015-05-26 19:04 | |
You forgot to actually attach the code. |
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| msg244127 - (view) | Author: Rony Batista (Rony Batista) | Date: 2015-05-26 19:06 | |
Silly me, Heres the code. |
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| msg244132 - (view) | Author: Ned Deily (ned.deily) * |
Date: 2015-05-26 20:22 | |
Without diving into the details of your test program, I get the same results on a 64-bit Debian Python 2.7.9 as with a 64-bit OS X 2.7.10:
c_uint32 TESTS:
Class Name exponent number Sign float binary repr
IEEE754Float_u ('-0x7b', '0xbeb2aL', 0L, 69.95930480957031, ['0x42', '0x8b', '0xeb', '0x2a'])
IEEE754Float_u ('-0x7b', '0xbeb2aL', 0L, 69.95930480957031, ['0x42', '0x8b', '0xeb', '0x2a'])
AN575Float_uint ('0x0', '0xbeb2a', 0L, 1.094551427887186e-39, ['0x0', '0xb', '0xeb', '0x2a'])
AN575Float_uint ('0x0', '0xbeb2a', 0L, 1.094551427887186e-39, ['0x0', '0xb', '0xeb', '0x2a'])
AN575Float_uint ('-0x7b', '0xbeb2a', 0L, 1.094551427887186e-39, ['0x85', '0xb', '0xeb', '0x2a'])
IEEE754Float_u ('-0x7b', '0xbeb2aL', 1L, -69.95930480957031, ['0xc2', '0x8b', '0xeb', '0x2a'])
AN575Float_uint ('-0x7b', '0xbeb2a', 1L, 1.094551427887186e-39, ['0x85', '0x8b', '0xeb', '0x2a'])
But using the same OS X 2.7.10 in 32-bit mode, I get:
c_uint32 TESTS:
Class Name exponent number Sign float binary repr
IEEE754Float_u ('-0x7b', '0xbeb2aL', 0L, 69.95930480957031, ['0x42', '0x8b', '0xeb', '0x2a'])
IEEE754Float_u ('-0x7b', '0xbeb2aL', 0L, 69.95930480957031, ['0x42', '0x8b', '0xeb', '0x2a'])
AN575Float_uint ('-0x7b', '0xbeb2a', 0L, 69.95930480957031, ['0x85', '0xb', '0xeb', '0x2a'])
AN575Float_uint ('-0x7b', '0xbeb2a', 0L, 69.95930480957031, ['0x85', '0xb', '0xeb', '0x2a'])
AN575Float_uint ('-0x7b', '0xbeb2a', 0L, 69.95930480957031, ['0x85', '0xb', '0xeb', '0x2a'])
IEEE754Float_u ('-0x7b', '0xbeb2aL', 1L, -69.95930480957031, ['0xc2', '0x8b', '0xeb', '0x2a'])
AN575Float_uint ('-0x7b', '0xbeb2a', 1L, -69.95930480957031, ['0x85', '0x8b', '0xeb', '0x2a'])
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| msg244223 - (view) | Author: Rony Batista (Rony Batista) | Date: 2015-05-27 22:57 | |
Well, looks like the issue is with 64 bit mode then. For the first 5 cases the right answer is 69.95930480957031, and for the last 2 its -69.95930480957031. The results for the 32 bit mode are all correct. |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:58:17 | admin | set | github: 68478 |
| 2015-05-27 22:57:25 | Rony Batista | set | messages: + msg244223 |
| 2015-05-26 20:22:05 | ned.deily | set | nosy:
+ ned.deily messages: + msg244132 |
| 2015-05-26 19:06:18 | Rony Batista | set | files:
+ ctypesBug.py messages: + msg244127 |
| 2015-05-26 19:04:35 | ronaldoussoren | set | nosy:
+ ronaldoussoren messages: + msg244126 |
| 2015-05-26 19:02:48 | Rony Batista | create | |