anchor.diff:  (defun descale (x n)
     (declare #.*optimize* (type fixnum x n))
     (the fixnum (ash (plus x (ash 1 (1- n))) (- n))))
  -
  -(defmacro plus3 (x y z)
  -  `(plus (plus ,x ,y) ,z))
  -
  -(defmacro mul3 (x y z)
  -  `(mul (mul ,x ,y) ,z))
   
   ;;; Implementation of Loeffer, Ligtenberg and Moschytz forward DCT
   (defun llm-dct (data)
  
positive.code: 
  ;;; Builds common decoding and encoding tables
  (defun build-universal-tables (bits)
    (let ((huffsize (make-array 256))
          (huffcode (make-array 256))
          (lastk 0))
      (declare #.*optimize* (type fixnum lastk)
               (type (simple-array t (*)) huffcode huffsize)
  	     (type uint8-array bits))
      ;; generating huffsize
        (loop for i fixnum from 1 to 16
  
negative.code:                  izigzag write-bits))
  
  (deftype uint8 () '(unsigned-byte 8))
  (deftype uint8-array () '(simple-array uint8 (*)))
  (deftype uint8-2d-array () '(simple-array uint8-array (*)))
  
  (deftype suint8 () '(signed-byte 8))
  (deftype sint8-array () '(simple-array sint8 (*)))
  (deftype sint8-2d-array () '(simple-array sint8-array (*)))
  
  (deftype sint16 () '(signed-byte 16))
  (deftype sint16-array () '(simple-array sint16 (*)))
  (deftype sint16-2d-array () '(simple-array sint16-array (*)))
  
  