(defun foo(n &optional (num (expt 2 31)))
  (let* (
	 (b (byte 8 n))
	 (c (ldb b num))
	 (s (format nil "~b" c))
     )
    (format t "~&8 bits starting at ~s of 16#~x (2#~b) = 16#~x (2#~b)~%" n num num c c)

    c))


(defun demo ()(dotimes (i 32) (foo i)))

(progn
(setq x #x410dc66f)
(setq b (byte 8 23))
(setq v (ldb b x))
)