(defun store-bits-from-octet (destination-bit-vector octet &key (start 0) end)
  (store-bits-from-integer destination-bit-vector octet
                           :start start
                           :end (min (+ start 8) (or end (length destination-bit-vector)))))

(with-open-file (stream path :element-type 'octet)
  (loop :with result := (make-array (* 8 (file-length stream)) :element-type 'bits)
        :for start :from 0 :by 8
        :for octet := (read-byte stream nil)
        :while octet
        :do (store-bits-from-octet result octet :start start)))