(defun C:FIXVPORT (/ ss i en ed flags newflags result)
  (setq ss (ssget "X" (list (cons 0 "VIEWPORT"))))
  (if (null ss)
    (princ "
[FIXVPORT] VP not found")
    (progn
      (princ (strcat "
[FIXVPORT] found: " (itoa (sslength ss))))
      (setq i 0)
      (while (< i (sslength ss))
        (setq en (ssname ss i))
        (setq ed (entget en))
        (if (assoc 90 ed)
          (progn
            (setq flags (cdr (assoc 90 ed)))
            (princ (strcat "
  VP" (itoa i) " flag90=" (itoa flags)))
            (if (> flags 65535)
              (progn
                (setq newflags (logand flags 65535))
                (princ (strcat " -> fix: " (itoa newflags)))
                (setq result (entmod (subst (cons 90 newflags) (assoc 90 ed) ed)))
                (if result
                  (progn (entupd en) (princ " OK"))
                  (princ " FAILED")))
              (if (< flags 0)
                (progn
                  (setq newflags (logand flags 65535))
                  (princ (strcat " -> fix(neg): " (itoa newflags)))
                  (setq result (entmod (subst (cons 90 newflags) (assoc 90 ed) ed)))
                  (if result
                    (progn (entupd en) (princ " OK"))
                    (princ " FAILED")))
                (princ " skip"))))
          (princ (strcat "
  VP" (itoa i) " no flag90")))
        (setq i (1+ i)))))
  (princ "
[FIXVPORT] done - try select now")
  (princ)
)

(princ "
[FIXVPORT] loaded - ºäÆ÷Æ® ¼±Åà ¾ÈµÉ¶§ »ç¿ë_KDJ")
(princ)