Checksums & SANE
Posted by: mcrm <mcrm@...>
This is really a two-part question: creating checksums and using SANE.
I am creating an algorithm that checks for duplicate files based on the
following criteria- Creation date, mod. date, size in bytes (logical
resource and data forks), type and creator. Creating a checksum for this
would be ideal, but I am not sure how to go about doing it. I know how
to get the data, but I am not sure exactly how to create a checksum (or
for that matter, a real clear idea on what a checksum is). If I simply
add the data I get from GETCATINFO into a key (like key = size +
creator& + type& ...) that will not be a true checksum since different
things can add up to the same number, but I believe the odds are truly
too small for worrying about that (feel free to correct me if you
disagree).
However, to add up several long ints I will need something bigger than a
four-byte variable. SANE supports a 64-bit variable, which I would like
to use. But what is the best way to implement SANE using double-long
integers, not floating point numbers? It seems as if the SANE.incl FNs
use the 80-bit floating pt. variable for operations and require you to
convert integers to floats to call the function and require you to
convert the floats back into dbl longs, which makes it much slower than
normal integer calculations. Is there a better way?
TIA & have a safe holidays!
Ryan McGann
mcrm@cs.purdue.edu, mcgann@expert.cc.purdue.edu