[Guido]
> Modified Files:
> test_zlib.py
> Log Message:
> Portable way of producing unsigned 32-bit hex output to print the
> CRCs.
>
>
> Index: test_zlib.py
> ===================================================================
> RCS file: /cvsroot/python/python/dist/src/Lib/test/test_zlib.py,v
> retrieving revision 1.18
> retrieving revision 1.19
> diff -C2 -d -r1.18 -r1.19
> *** test_zlib.py 23 Jul 2002 19:04:09 -0000 1.18
> --- test_zlib.py 12 Aug 2002 15:26:05 -0000 1.19
> ***************
> *** 13,18 ****
>
> # test the checksums (hex so the test doesn't break on 64-bit machines)
> ! print hex(zlib.crc32('penguin')), hex(zlib.crc32('penguin', 1))
> ! print hex(zlib.adler32('penguin')), hex(zlib.adler32('penguin', 1))
>
> # make sure we generate some expected errors
> --- 13,20 ----
>
> # test the checksums (hex so the test doesn't break on 64-bit machines)
> ! def fix(x):
> ! return "0x%x" % (x & 0xffffffffL)
> ! print fix(zlib.crc32('penguin')), fix(zlib.crc32('penguin', 1))
> ! print fix(zlib.adler32('penguin')), fix(zlib.adler32('penguin', 1))
>
> # make sure we generate some expected errors
This raises a question: what should crc32 and adler32 return? They return
32-bit values, and that's part of external definitions so we can't change
that, but how we *view* "the sign bit" is up to us. binascii.crc32()
always-- even on 64-bit boxes --returns a value in range(-2**31, 2**31). I
know that because I forced it to not long ago. I don't know what the other
guys return (zlib.crc32(), zlib.adler32(), ...?).
It would sure be nice if they returned values in range(0, 2**32) instead. A
difficulty with changing this stuff is that checksums seem frequently to be
read and written via the struct module, with format code "l", and e.g.
>>> struct.pack("!l", 1L << 31)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
OverflowError: long int too large to convert to int
>>>
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