Hello, I have previously mailed on list that I am trying to port rsync to NT. I was wondering that whether CRC can be used to find check sums rather then rolling algorithm. I havnt found any document on web comparing rolling algorithm with CRC. -- Hasanatkazmi@gmail.com "I hate Capitalism,so naturally I love Open Source" -- Hasanat Kazmi +923464362473 -------------- next part -------------- HTML attachment scrubbed and removed
On Fri, May 22, 2009 at 9:02 AM, Hasanat Kazmi <hasanatkazmi@gmail.com> wrote:> Hello, > I have previously mailed on list that I am trying to port rsync to NT. I was > wondering that whether CRC can be used to find check sums rather then > rolling algorithm. I havnt found any document on web comparing rolling > algorithm with CRC. >CRC doesn't have the correct properties for rsync, in that you cannot "subtract" previous bytes from the current hash in an efficent way. This is what enables rsync to compute the hash at every byte of the file in an efficient manner. For more info, read Tridgell's thesis paper at: http://samba.org/~tridge/phd_thesis.pdf -- RPM
Hasanat Kazmi wrote:> Hello, > I have previously mailed on list that I am trying to port rsync to NT. I was > wondering that whether CRC can be used to find check sums rather then rolling > algorithm. I havnt found any document on web comparing rolling algorithm with > CRC.It will only find non-block-aligned matches if you can do a rolling CRC... -- Jamie