zlib.crc32() not cross-platform

[bencollver]

BPO	1678102

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2007-03-13.22:52:26.000>
created_at = <Date 2007-03-10.23:07:43.000>
labels = ['invalid', 'library']
title = 'zlib.crc32() not cross-platform'
updated_at = <Date 2007-03-13.22:52:26.000>
user = 'https://bugs.python.org/bencollver'

bugs.python.org fields:

activity = <Date 2007-03-13.22:52:26.000>
actor = 'ggenellina'
assignee = 'none'
closed = True
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2007-03-10.23:07:43.000>
creator = 'bencollver'
dependencies = []
files = []
hgrepos = []
issue_num = 1678102
keywords = []
message_count = 3.0
messages = ['31476', '31477', '31478']
nosy_count = 2.0
nosy_names = ['ggenellina', 'bencollver']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue1678102'
versions = ['Python 2.5']

[bencollver]

The zlib.crc32() function sometimes produces different results for the same input on big and little-endian processors. Same for zlib.adler32().

sparc64:
>>> import zlib
>>> print zlib.adler32("--------------------------------------------------", 1)
> 3763407051
>>> print zlib.crc32("--------------------------------------------------", 1)
3044228349

i386:
>>> import zlib
>>> print zlib.adler32("--------------------------------------------------", 1)
> -531560245
>>> print zlib.crc32("--------------------------------------------------", 1)
-1250738947

[bencollver]

The extra > characters before the first results come from me pasting the results to my irc client, then copying from there and pasting here. Sorry for any confusion.

[ggenellina]

py> -531560245 & 0xffffffff
3763407051L

It's the same number (actually, the same bit pattern). The i386 version is signed, the other unsigned. The i386 platform uses a 32 bit "int"; the sparc64 uses 64 bits (I presume). 3763407051 doesnt fit in 31bits, so it's seen as a negative number.