Dirk Eddelbuettel
2005-Mar-01 14:17 UTC
[Rd] Can crc32() assume to be available at the C level?
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
Prof Brian Ripley
2005-Mar-01 16:04 UTC
[Rd] Can crc32() assume to be available at the C level?
On Tue, 1 Mar 2005, Dirk Eddelbuettel wrote:> 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?It is present, but with --with-zlib options it could be in an external library and hence not exported by R.bin/libR.so. So I don't think you can rely on finding it. -- Brian D. Ripley, ripley@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595