exmpl.clj

(defn data-sum [^bytes data]
  (let [count-data (count data)]
    (loop [i 0 sum 0]
      (let [val (hx/get-byte data i)
            new-sum (+ sum val)]
        (if (< i (dec count-data))
          (recur (inc i) new-sum) new-sum)))))

(defn valid-CS? [^bytes data]
  (let [count-data (count data)
        origin-CS (aget data (- count-data 2))
        unixtime (hx/subbytes data 5 9)
        frames (get-frames data)
        unixtime-sum (data-sum unixtime)
        frames-sum (reduce + (map data-sum frames))
        CS (hx/int->int8 (+ unixtime-sum frames-sum))]
    (= origin-CS CS)))