lispdoc - results for rotatef

(rotatef &rest args &environment env)
Function: Takes any number of SETF-style place expressions. Evaluates all of the expressions in turn, then assigns to each place the value of the form to its right. The rightmost form gets the value of the leftmost. Returns NIL.
(defun swap-bytes (code)
  (assert (<= code 65535))
  (rotatef (ldb (byte 8 0) code)
           (ldb (byte 8 8) code))
Mentioned in:
CLtL2 - 7.2. Generalized Variables
HyperSpec - Macro ROTATEF
On Lisp - Functional Design
PCL - other ways to modify places
PCL - string types