hexgolf.lisp

(destructuring-bind (offset in-path out-path) (cdr sb-ext:*posix-argv*)
  (with-open-file (in in-path :element-type '(unsigned-byte 8))
    (with-open-file (out out-path :direction :output :if-exists :supersede)
      (do ((c (make-array 32)) (n 0) (a (parse-integer offset :radix 16) (+ a n)))
          ((zerop (setq n (read-sequence c in))))
        (format out ":~2,'0X~4,'0X00" n a)
        (format out "~2,'0X~%" (mod (- (apply #'+ a (ash a -8) n (map 'list (lambda (b) (format out "~2,'0X" b) b) (subseq c 0 n)))) 256)))
      (format out ":00000001FF~%"))))