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

(module string-hexadecimal

(;export
  string->hex *string->hex)

(import scheme chicken)

(import
  (only lolevel number-of-bytes)
  (only to-hex str_to_hex)
  (only type-checks check-natural-fixnum check-string))
(require-library lolevel to-hex type-checks)

(declare
  (bound-to-procedure
    ##sys#signal-hook))

;;

(define (string->hex str #!optional (start 0) (end #f))
  (check-string 'string->hex str)
  (check-natural-fixnum 'string->hex start 'start)
  (let ((end
        (or
          (and end (check-natural-fixnum 'string->hex end 'end))
          (number-of-bytes str))))
    (unless (<= start end)
      (##sys#signal-hook
        #:bounds-error 'string->hex
        "illegal subvector specification" start end))
    (*string->hex str start end) ) )

(define (*string->hex str start end)
  (let ((len (fx- end start)))
    (if (fx= 0 len)
      ""
      (str_to_hex (make-string (fx* len 2)) str start len) ) ) )

) ;module string-hexadecimal