Impenetrable Code

However elegant a programming language, some fool will always find a way to write ugly code.

Here's a word I recently implemented in Forth:

: C
>R
256 15 16 1799
4 13107 2 21845
R>
4 0 DO
TUCK OVER AND -ROT
INVERT AND ROT / +
LOOP
;

Although I didn't set out to intentionally create something hideous, I'm appalled by how difficult to understand the code is. How can I make the word easier to comprehend and can you remind me what it's supposed to do?