muforth/lib/rot13.mu4

( This file is part of muFORTH: http://pages.nimblemachines.com/muforth

  Copyright 2002-2008 David Frech. All rights reserved, and all wrongs
  reversed. (See the file COPYRIGHT for details.)

: r13  dup bl xor if dup 13 + swap 32 bic 13 + char Z > if -26 + then then ;
: c@+  ( a - ch a+)  dup c@  swap 1+ ;
: rot13  ?for c@+ swap  r13 emit next drop ;