anchor.diff:  (defun izigzag8 (inbuf zzbuf)
     (declare #.*optimize*
              (type uint8-array inbuf)
  -	   (type uint8-2d-array zzbuf))
  +	   (type uint8-2d-array zzbuf +zigzag-index+))
     "Performs inverse zigzag block arrangement"
  -  (loop for zrow across +zigzag-index+
  -        for row across zzbuf do
  +  (loop for zrow of-type uint8-array across +zigzag-index+
  +        for row of-type uint8-array across zzbuf do
           (loop for pos fixnum across zrow
                 for x fixnum from 0 do
                 (setf (aref row x) (aref inbuf pos))))
  
positive.code:   "The DECODE procedure, as described in CCITT rec."
    (let ((i 1)
          (code (funcall nextbit s)))
      (loop while (> code (aref maxcode i)) do
            (incf i)
            (setf code (plus (ash code 1) (funcall nextbit s))))
  
negative.code:                                   for pos fixnum = (position cid (descriptor-cid image))
                                    collecting (list (aref (descriptor-iH image) pos)
                                                     (aref (descriptor-iV image) pos)))))
           (preds (make-array ncomp :initial-element 0 :element-type 'sint16))
           (tables (make-array ncomp
                       :initial-contents
                       (loop for i fixnum from 0 below ncomp
                             for ta fixnum = (logand (second (aref (scan-cdesc scan) i)) 15)
                             for td fixnum = (ash (the fixnum (second (aref (scan-cdesc scan) i))) -4)
                             collecting (vector (aref (descriptor-huff-ac image) ta)
                                                (aref (descriptor-huff-dc image) td))))))
      (declare #.*optimize*
               (type fixnum ncomp Hmax Vmax x-growth y-growth nwidth)
               (type (simple-array t (*)) freqs fr tables)
               (dynamic-extent fr freqs))
      (catch 'marker
        (loop
          do (loop for comp fixnum from 0 below ncomp
                   for pos fixnum =
                      (position (the fixnum (first (aref (scan-cdesc scan) comp)))
  