anchor.diff:                     (declare (type (unsigned-byte ,bitsize) value))
                      (multiple-value-bind (vector start end)
                          (array-data-and-offsets buffer index (+ index ,bytes))
  +                     #+sbcl (declare (optimize (sb-c::insert-array-bounds-checks 0)))
  +                     (declare (type (integer 0 ,(- array-dimension-limit bytes)) start))
                        (declare (ignore end))
  -                     ,@(loop for i from 1 to bytes
  -                             collect (let ((offset (if big-endian-p
  -                                                       (- bytes i)
  -                                                       (1- i))))
  -                                       `(setf (aref vector (+ start ,offset))
  -                                              (ldb (byte 8 ,(* 8 (1- i))) value))))
  -                     value))
  +                     ,(set-form 'vector 'start 'value bytes big-endian-p)))
                    (defsetf ,ref-name ,set-name))))
              (define-fetchers-and-storers (bitsize)
                  (loop for i from 0 below 4
  
positive.code:     (values v start end))
    #-(or sbcl cmu)
    (values v start (or end (length v))))
  
  (macrolet ((define-fetcher (bitsize signedp big-endian-p)
               (let ((ref-name (byte-ref-fun-name bitsize signedp big-endian-p))
  
negative.code:                   (declare (type (integer 0 ,(- array-dimension-limit bytes)) index))
                    (multiple-value-bind (vector start end)
                        (array-data-and-offsets buffer index (+ index ,bytes))
                       #+sbcl (declare (optimize (sb-c::insert-array-bounds-checks 0)))
                       (declare (type (integer 0 ,(- array-dimension-limit bytes)) start))
                      (declare (ignore end))
                      ,(ref-form 'vector 'start bytes signedp big-endian-p)))))
             (define-storer (bitsize signedp big-endian-p)
               (let ((ref-name (byte-ref-fun-name bitsize signedp big-endian-p))
                     (set-name (byte-set-fun-name bitsize signedp big-endian-p))
  