0> In article <28313007-F338-4CF6-ACAD-FB46DC1DC800@gmx.net>, 0> Robert Vollmert <URL:mailto:rvollmert-lists@gmx.net> ("Robert") wrote: Robert> This compiles, at least, and probably does what I want: Robert> + // calculate normalized differences Robert> + int max = 1 << (24-shift); Robert> + int dx = (lon - lastLong) % (1 << (24-shift)); Robert> + if (dx >= max/2) dx -= max/2; Robert> + int dy = (lat - lastLat) % (1 << (24-shift)); Robert> + if (dy >= max/2) dy -= max/2; Robert> Robert> lastLong = lon; Robert> lastLat = lat; I'd suggest helping the compiler by putting that (1 << (24-shift)) into a (local) constant. Actually, using the fact that a Java int is 32-bit and signed, you can do something like (untested) /-------- | final int offset = 8+shift; | int dx = (lon - lastLong) << offset >> offset; | ind dy = (lat - lastLat) << offset >> offset; \-------- to truncate and sign-extend those values. This approach will probably run faster on most hardware, as I've eliminated those conditionals. I've not read and understood enough of the code to work out whether the sign extension is really required; if not, a simple AND mask may be sufficient.