[Rd] Can crc32() assume to be available at the C level?

[Dirk Eddelbuettel]

Dear R-develers,

Antoine Lucas suggested extending my small digest package (which provides md5
and sha-1 digests of R objects, which it are serialized if needed) with a
crc32 function, and provided a fairly complete patch.

We are now wondering if we should play it safe and bundle crc32.c (plus
utils) in the digest sources (as I do with md5 and sha1), or if we can assume
that crc32 is present on all R platforms thanks to zlib. 

Is that the case?  If so, is it a good idea to use it even though it doesn't
appear in the header files?  Or should we package "our" copy?

Thanks in advance for any advice, Dirk

-- 
Better to have an approximate answer to the right question than a precise 
answer to the wrong question.  --  John Tukey as quoted by John Chambers