; slots
(define rand #f)
(define randint #f)
(let ((two31 #x80000000) (a (make-vector 56 -1)) (fptr #f))
(define (mod-diff x y) (modulo (- x y) two31)) ; generic version
; (define (mod-diff x y) (logand (- x y) #x7FFFFFFF)) ; fast version
(define (flip-cycle)
(do ((ii 1 (+ ii 1)) (jj 32 (+ jj 1))) ((< 55 jj))
(vector-set! a ii (mod-diff (vector-ref a ii) (vector-ref a jj))))
(do ((ii 25 (+ ii 1)) (jj 1 (+ jj 1))) ((< 55 ii))
(vector-set! a ii (mod-diff (vector-ref a ii) (vector-ref a jj))))
(set! fptr 54) (vector-ref a 55))
(define (init-rand seed)
(let* ((seed (mod-diff seed 0)) (prev seed) (next 1))
(vector-set! a 55 prev)
(do ((i 21 (modulo (+ i 21) 55))) ((zero? i))
(vector-set! a i next) (set! next (mod-diff prev next))
(set! seed (+ (quotient seed 2) (if (odd? seed) #x40000000 0)))
(set! next (mod-diff next seed)) (set! prev (vector-ref a i)))
(flip-cycle) (flip-cycle) (flip-cycle) (flip-cycle) (flip-cycle)))
(define (next-rand)
(if (negative? (vector-ref a fptr)) (flip-cycle)
(let ((next (vector-ref a fptr))) (set! fptr (- fptr 1)) next)))
(define (unif-rand m)
(let ((t (- two31 (modulo two31 m))))
(let loop ((r (next-rand)))
(if (<= t r) (loop (next-rand)) (modulo r m)))))
(init-rand 19380110) ; happy birthday donald e knuth
(set! rand (lambda seed
(cond ((null? seed) (/ (next-rand) two31))
((eq? (car seed) 'get) (cons fptr (vector->list a)))
((eq? (car seed) 'set) (set! fptr (caadr seed))
(set! a (list->vector (cdadr seed))))
(else (/ (init-rand (modulo (numerator
(inexact->exact (car seed))) two31)) two31)))))
(set! randint (lambda args
(cond ((null? (cdr args))
(if (< (car args) two31) (unif-rand (car args))
(floor (* (next-rand) (car args)))))
((< (car args) (cadr args))
(let ((span (- (cadr args) (car args))))
(+ (car args)
(if (< span two31) (unif-rand span)
(floor (* (next-rand) span))))))
(else (let ((span (- (car args) (cadr args))))
(- (car args)
(if (< span two31) (unif-rand span)
(floor (* (next-rand) span))))))))))
(define wheel #("BAR" "BELL" "ORANGE" "LEMON" "PLUM" "CHERRY"))
(define (display-instructions)
(display "WELCOME TO THE CASINO") (newline)
(display "BET IN INCREMENTS OF $1 FROM $1 TO $100") (newline)
(display "BET $0 WHEN YOU ARE FINISHED") (newline))
(define (pull n)
(let ((x (randint 6)) (y (randint 6)) (z (randint 6)))
(display (vector-ref wheel x)) (display " ")
(display (vector-ref wheel y)) (display " ")
(display (vector-ref wheel z)) (newline)
(cond ((= x y z 0)
(let ((d (* 101 n)))
(display "***JACKPOT***") (newline)
(display "YOU WIN $") (display d) (newline) d))
((= x y z)
(let ((d (* 11 n)))
(display "***TOP DOLLAR***") (newline)
(display "YOU WIN $") (display d) (newline) d))
((or (= x y 0) (= x z 0) (= y z 0))
(let ((d (* 6 n)))
(display "***DOUBLE BAR***") (newline)
(display "YOU WIN $") (display d) (newline) d))
((or (= x y) (= x z) (= y z))
(let ((d (* 3 n)))
(display "***DOUBLE***") (newline)
(display "YOU WIN $") (display d) (newline) d))
(else (display "YOU LOSE $") (display n) (newline) (- n)))))
(define (play)
(display-instructions)
(display "ENTER YOUR BET: ")
(let loop ((bet (read)) (purse 0))
(cond ((or (not (integer? bet)) (negative? bet))
(display "ENTER YOUR BET: ")
(loop (read) purse))
((< 100 bet)
(display "HOUSE LIMIT $100") (newline)
(display "ENTER YOUR BET: ") (loop (read) purse))
((<= 1 bet 100)
(let* ((p (pull bet)) (purse (+ p purse)))
(cond ((positive? purse)
(display "YOU HAVE $") (display purse))
((negative? purse)
(display "YOU OWE $") (display (- purse)))
(else (display "YOU ARE EVEN")))
(newline) (display "ENTER YOUR BET: ")
(loop (read) purse)))
((negative? purse)
(display "PLACE $") (display (- purse))
(display " ON THE KEYBOARD") (newline))
((positive? purse)
(display "COLLECT $") (display purse)
(display " FROM THE CASHIER") (newline))
(else (display "YOU BROKE EVEN") (newline)))))