anchor.diff:                  (setf (svref buffer pv) ; RED
                         (the fixnum (limit (plus yy (svref *cr-r-tab* cr)))))))))
   
  -;;; Frame decoding subroutine
  -(defun decode-frame (image s)
  +(defun decode-frame-beginning (image s)
     (read-byte s) ; length
     (read-byte s)
     (read-byte s) ; sample precision
  
positive.code:                    (descriptor-height image)
                     (descriptor-width image)
                     (descriptor-ncomp image)))
            (t (error "Unsupported JPEG format")))))
  
  ;;; Top level decoder function
  (defun decode-image (filename)
    (with-open-file (in filename :direction :input :element-type 'unsigned-byte)
      (decode-stream in)))
  
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;; Here are some useful routines
  
negative.code:       (inverse-colorspace-convert image))))
  
  (defun decode-stream (stream)
    "Return image array, height, width, and number of components. Does not support
  progressive DCT-based JPEGs."
    (unless (= (read-marker stream) +M_SOI+)
      (error "Unrecognized JPEG format"))
    (let* ((image (make-descriptor))
  