The devel/diffutiltcl port
diffutiltcl-0.4.2 – diff functions for Tcl
A Tcl extension providing utilities for comparisons of strings, lists and files.
The base comparison is a Longest Common Substring algorithm based on
J. W. Hunt and M. D. McIlroy, "An algorithm for differential file comparison,"
Comp. Sci. Tech. Rep. #41, Bell Telephone Laboratories (1976).
Available on the Web at the second author's personal site:
It is basically an LCS diff algorithm implemented in C on top of Tcl's API,
thus giving full Unicode and VFS support.