(module mac mzscheme
        (require (lib "pregexp.ss"))
        (require (lib "list.ss"))
        (require "mac-win32.scm")
        (require "mac-unix.scm")
        (provide get-mac-address
                 mac-address-of-this-host?
                 available-mac-addresses
                 good-mac-address?
                 mac-address->vector
                 possible-mac-addresses
                 )
        
        (define get-mac-addresses (if (eq? (system-type 'os) 'windows)
                                      get-mac-addresses-win32
                                      get-mac-addresses-unix))
        
        (define (hex->dec d)
          (cond ((eq? d #\0) 0)
                ((eq? d #\1) 1)
                ((eq? d #\2) 2)
                ((eq? d #\3) 3)
                ((eq? d #\4) 4)
                ((eq? d #\5) 5)
                ((eq? d #\6) 6)
                ((eq? d #\7) 7)
                ((eq? d #\8) 8)
                ((eq? d #\9) 9)
                ((eq? d #\a) 10)
                ((eq? d #\b) 11)
                ((eq? d #\c) 12)
                ((eq? d #\d) 13)
                ((eq? d #\e) 14)
                ((eq? d #\f) 15)))
                
        (define (mac-address->vector A)
          (list->vector
           (map (lambda (part)
                  (let ((u (string-ref part 0))
                        (l (string-ref part 1)))
                    (+ (* (hex->dec u) 16) (hex->dec l))))
                (pregexp-split "[-:]" (string-downcase A)))))
        
        (define (good-mac-address? A)
          (let ((re (pregexp (format "~a~a~a" "^" (re-mac) "$"))))
            (if (pregexp-match re A)
                (let ((adr (mac-address->vector A)))
                  (if (or (= (vector-ref adr 1) 0)
                          (= (vector-ref adr 1) 255))
                      #f
                      #t)))))
        
        (define (get-mac-address)
          (letrec ((f (lambda (adrs)
                        (if (null? adrs)
                            #f
                            (if (good-mac-address? (car adrs))
                                (car adrs)
                                (f (cdr adrs)))))))
            (f (sort (get-mac-addresses) string-ci<?))))
        
        (define (available-mac-addresses)
          (get-mac-addresses))
        
        (define (possible-mac-addresses)
          (sort (filter good-mac-address? (available-mac-addresses))
                string-ci<?))
        
        (define (mac-address-of-this-host? A)
          (letrec ((f (lambda (adrs)
                        (if (null? adrs)
                            #f
                            (if (string-ci=? A (car adrs))
                                #t
                                (f (cdr adrs)))))))
            (f (available-mac-addresses))))
                                            
        )