[Python-3000] binascii.crc32 vs zlib.crc32

[Guido van Rossum]

Hm.  zlib is an odd place to find this API (unless you know way more
about gzip than healthy :-).  Though binascii isn't much better.  I'd
rather expect this in the vicinity of md5 and sha... Is it possible to
tweak that C code to use the zlib version if present and the old C
code otherwise?

On Tue, Mar 18, 2008 at 3:21 PM, Gregory P. Smith <greg at krypto.org> wrote:
> Both modules have a crc32 function.  The zlib version is faster when zlib
> has been compiled optimally or about the same when zlib is old or uses its C
> code.
>
> Should we ditch the binascii.crc32 version in py3k?
>
>  64bit Linux (CentOS 5.1):
>
> $ python2.4 -m timeit 'foo="abcdefghijklmnop"*10' 'import binascii as mod'
> 'f = mod.crc32' 'for x in xrange(100000): f(foo)'
>  10 loops, best of 3: 108 msec per loop
> $ python2.4 -m timeit 'foo="abcdefghijklmnop"*10' 'import zlib as mod' 'f =
> mod.crc32' 'for x in xrange(100000): f(foo)'
>  10 loops, best of 3: 40.5 msec per loop
>
> 32bit MacOS X 10.4:
>
> % python2.3 /usr/lib/python2.3/timeit.py 'foo="abcdefghijklmnop"*10' 'import
> binascii as mod' 'f = mod.crc32' 'for x in xrange(100000): f(foo)'
>  10 loops, best of 3: 7.37e+04 usec per loop
> % python2.3 /usr/lib/python2.3/timeit.py 'foo="abcdefghijklmnop"*10' 'import
> zlib as mod' 'f = mod.crc32' 'for x in xrange(100000): f(foo)'
>  10 loops, best of 3: 4.62e+04 usec per loop
>
> Removal from binascii would break things for platforms or embedded systems
> wanting crc32 that don't want to include zlib.  Anyone care?
>
> What about 2.x?  if we remove the redundancy in py3k i guess we deprecate
> binascii.crc32 and remove in 2.7?
>
> -gps
>
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-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)