; john horton conway's game of life
(define (make-matrix rows columns . value)
(do ((m (make-vector rows)) (i 0 (+ i 1)))
((= i rows) m)
(if (null? value)
(vector-set! m i (make-vector columns))
(vector-set! m i (make-vector columns (car value))))))
(define (matrix-rows x) (vector-length x))
(define (matrix-cols x) (vector-length (vector-ref x 0)))
(define (matrix-ref m i j) (vector-ref (vector-ref m i) j))
(define (matrix-set! m i j x) (vector-set! (vector-ref m i) j x))
(define-syntax for
(syntax-rules ()
((for (var first past step) body ...)
(let ((ge? (if (< first past) >= <=)))
(do ((var first (+ var step)))
((ge? var past))
body ...)))
((for (var first past) body ...)
(let* ((f first) (p past) (s (if (< first past) 1 -1)))
(for (var f p s) body ...)))
((for (var past) body ...)
(let* ((p past)) (for (var 0 p) body ...)))))
(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 esc (integer->char 27))
(define (cls)
(display esc) (display #\[)
(display #\2) (display #\J))
(define (hide-cursor)
(display esc) (display #\[) (display #\?)
(display #\2) (display #\5) (display #\l))
(define (show-cursor)
(display esc) (display #\[) (display #\?)
(display #\2) (display #\5) (display #\h))
(define (goto r c)
(display esc) (display #\[) (display r)
(display #\;) (display c) (display #\H))
(define max-r 24) (define max-c 39)
(define (show grid)
(for (r 0 max-r)
(for (c 0 max-c)
(when (matrix-ref grid r c)
(goto r (+ c c 1)) (display #\*)))))
(define (neighbors grid r c)
(define (cell rc)
(if (matrix-ref grid (modulo (+ r (car rc)) max-r)
(modulo (+ c (cadr rc)) max-c))
1 0))
(apply + (map cell
'((-1 -1) (-1 0) (-1 1) (0 -1) (0 1) (1 -1) (1 0) (1 1)))))
(define (life init)
(cls) (hide-cursor) (show init)
(let ((next (make-matrix max-r max-c)))
(for (r 0 max-r)
(for (c 0 max-c)
(matrix-set! next r c
(or (and (matrix-ref init r c)
(<= 2 (neighbors init r c) 3))
(and (not (matrix-ref init r c))
(= (neighbors init r c) 3))))))
(life next)))
(define (rand-init)
(let ((grid (make-matrix max-r max-c #f)))
(for (r 0 max-r)
(for (c 0 max-c)
(if (< (rand) 1/2) (matrix-set! grid r c #t))))
grid))
(define glider
(let ((grid (make-matrix max-r max-c #f)))
(matrix-set! grid 0 1 #t)
(matrix-set! grid 1 2 #t)
(matrix-set! grid 2 0 #t)
(matrix-set! grid 2 1 #t)
(matrix-set! grid 2 2 #t)
grid))