;;;; string-hexadecimal.scm  -*- Hen -*-
;;;; Kon Lovett, Aug '10

(module string-hexadecimal

  (;export
    string->hex)

  (import
    scheme
    chicken
    (only to-hex str_to_hex)
    (only type-checks check-natural-fixnum check-string))

  (require-library to-hex type-checks)

  (declare
    (bound-to-procedure
      ##sys#signal-hook ##sys#size ##sys#make-string))

;;

(define (string->hex str #!optional (start 0) (end #f))
  (check-string 'string->hex str)
  (check-natural-fixnum 'string->hex start 'start)
  (when end (check-natural-fixnum 'string->hex end 'end))
  (let ((end (or end (##sys#size str))))
    (unless (<= start end)
      (##sys#signal-hook #:bounds-error 'string->hex
                         "illegal subvector specification" start end))
    (let ((len (- end start)))
      (if (= 0 len)
        ""
        (let ((res (##sys#make-string (* len 2))))
          (str_to_hex res str start len)
          res ) ) ) ) )

) ;module string-hexadecimal