XC=BASIC supports third-party extensions since version 2.2. Extensions are includable source files that define
Extensions can be written in assembly language or in XC=BASIC as well if speed is not crucial.
Just use the INCLUDE directive to include the extension into your program:
include "path/to/extension.bas"
After this point you can use all the new symbols that the extension defines.
Please refer to this tutorial.
Here are some extensions that would be cool to have: