Looks like I want rollsum.c/h from librsync (http://librsync.sourcefor
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Rolling Checksum Algorithm
I'm looking for a rolling checksum algorithm that computes the checksum for all x-line chunks in a file (including overlapping chunks). I don't think the matching does not need to be precise but it does need to be fast.
Where do I find an algorithm like this? I know rsync uses something like this, but can I use the rolling checksum algorithm without GPL'ing my application? Where do I find an algorithm like this?
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Answers
Well, the algoritm is explained in detail at http://samba.anu.edu.au/rs
I don't understand the algorithm well enough to make a distinction between rolling in and rolling out (the articles you linked to don't make this distinction; they assume fixed-chunk size). This difference is required if lines are of different lengths, however. Arguably I could change my use of the checksum to be byte-based instead of line-based, and arguably I can (and likely should) take the time to understand it more thoroughly. But this is one reason I was interested in librsync's implementation.
As it is, I didn't ask for an implementation but for an algorithm, which you gave me. Thanks.
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by: jkrPosted on 2005-09-08 at 12:10:01ID: 14847189
Check out
http://samba.anu.edu.au/rs
http://samba.anu.edu.au/rs
http://samba.anu.edu.au/rs
Also, http://en.wikipedia.org/wi