anchor.diff:    (multiple-value-bind (vname devices)
         (pci-find-vendor vid ids)
       (when (and vname devices)
  -      (let ((position (bsearch did devices 3)))
  +      (let ((position (bsearch did devices :stride 3)))
           (when position
             (values vname
                     (aref devices (+ position 1))
  
positive.code:       ((< imax imin)
         nil)
      (let* ((imid (truncate (+ imin imax) 2))
             (elt (aref vector (* imid stride))))
        (cond ((< elt item) (setf imin (1+ imid)))
              ((> elt item) (setf imax (1- imid)))
              (t (return (* imid stride)))))))
  
  (defun pci-find-vendor (id &optional (ids *pci-ids*))
    (let ((position (bsearch id ids 3)))
      (when position
        (values (aref ids (+ position 1))
                (aref ids (+ position 2))))))
  
negative.code: 
  (declaim (special *pci-ids*))
  
  (defun bsearch (item vector &key (stride 1) (key 'identity))
    "Locate ITEM using a binary search through VECTOR."
    ;; IMIN/IMAX are inclusive indicies.
    (do ((imin 0)
  