damn, I had implicitly assumed signed characters when writing the

damn, I had implicitly assumed signed characters when writing the
rolling checksum code. The result is that rsync worked much more
slowly when going between two machines where one of the machines uses
signed and the other unsigned chars. The rolling checksum rarely
matched so effectively a copy was done in many cases. The data always
came through correctly so no file corruption occurred but it's pretty
pointless using rsync if it doesn't speed things up!
I've now made the sign of the chars explicit