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Random Integer From Dev

random-integer

Read four bytes from /dev/urandom and construct an integer.

-Eric

 (define *integer-length* 4) ; integer length in bytes

 (define (bytes->integer byte-string)
  (let ((l (map char->ascii (string->list byte-string))))
    (let loop ((b l) (r 0) (d 0))
      (if (null? b)
	  r
	  (loop (cdr b)	(bitwise-ior r (arithmetic-shift (car b) d))
		(+ d 8))))))

 (define (random-integer)
  (let ((port (open-input-file "/dev/urandom")))
    (cond 
     ((read-string *integer-length* port)
      => (lambda (r)
	   (close-input-port port)
	   (bytes->integer r)))
     (else
      (error "Could not read from /dev/urandom")))))

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