anchor.diff:  
   (defun write-bits (bi ni s)
     (declare #.*optimize*
  -           (special *prev-length* *prev-byte*)
  -           (type fixnum bi ni *prev-length* *prev-byte*)
  +           ;(special *prev-length* *prev-byte*)
  +           (type fixnum bi ni)
              (type stream s))
     (loop with lim fixnum = (if (> ni 8) 1 0)
           for i fixnum from lim downto 0 do
  
positive.code:     #(99 99 99 99 99 99 99 99)
      #(99 99 99 99 99 99 99 99)))
  
  (defconstant *q-luminance-hi*
    #(#(10 7 6 10 15 25 32 38)
      #(8 8 9 12 16 36 38 34)
      #(9 8 10 15 25 36 43 35)
  
negative.code:                 (2 #(0 1))
                  (4 #(0 1 2 3))
                  (otherwise (error "Illegal number of components specified")))))
      (declare (special *zz-result* *prev-byte* *prev-length*)
  	     (type fixnum *prev-length* *prev-byte*))
      (cond ((/= ncomp (length sampling))
             (error "Wrong sampling list for ~D component(s)" ncomp))
            ((> (length q-tabs) ncomp)
  