anchor.diff:                             (x c-array-index)
                              (y c-array-index))
       foreign-pointer
  +  #+sbcl(declare (sb-ext:muffle-conditions sb-ext:compiler-note))
     (declare (optimize (speed 3) (safety 0) (debug 1))
              (inline inc-pointer c-array-pointer))
     (the cffi-sys:foreign-pointer
  
positive.code:                                 (x c-array-index)
                                  (y c-array-index))
      t
    (declare (optimize (speed 3) (safety 0) (debug 1))
             (inline ptr-index-2d))
    (let ((ptr (ptr-index-2d c-array x y))
  
negative.code:                          (y c-array-index)
                           (z c-array-index))
      t
    #+sbcl(declare (sb-ext:muffle-conditions sb-ext:compiler-note))
    (declare (optimize (speed 3) (safety 0) (debug 1))
             (inline ptr-index-3d))
    (let ((ptr (ptr-index-3d c-array x y z))
  