;;;; entropy-clock.scm
;;;; Kon Lovett, Oct '09

(module entropy-clock

  (;export
    make-entropy-source-system-clock)

  (import
    scheme
    chicken
    foreign
    entropy-source
    entropy-support)

  (require-library entropy-source entropy-support)

;;;

#>
#include <time.h>
#include <math.h>

static double
f64init()
{
  return (double) time( NULL );
}

static double
f64rand( double f64seed )
{
  double x = 11.0 + (25214903917.0 * f64seed);
  return fmod( x, 281474976711000.0 );
}

#undef MODULO
<#


(define f64init (foreign-lambda double "f64init"))
(define f64rand (foreign-lambda double "f64rand" double))

;;; Entropy from system clock

(define (make-entropy-source-system-clock)
  (let ((f64seed (f64init)))
    (let ((_f64rand (lambda () (set! f64seed (f64rand f64seed)) f64seed)))
      (*make-entropy-source
        ;
        make-entropy-source-system-clock
        ;
        'system-clock
        ;
        "Entropy from system clock"
        ;
        (make-entropic-u8/f64 _f64rand)
        ;
        _f64rand
        ;
        (lambda (u8cnt u8vec) (entropic-u8vector-filled/f64 u8cnt u8vec _f64rand) )
        ;
        (lambda (f64cnt f64vec) (entropic-f64vector-filled f64cnt f64vec _f64rand) ) ) ) ) )

(register-entropy-source! 'system-clock make-entropy-source-system-clock)

) ;module entropy-clock