;;; Timers
(define (make-timer)
- '((start . 0) (paused . 0) (state . stopped)))
+ (let ((start 0) (paused 0) (state 'stopped))
+ (lambda (op)
+ (case op
+ ((start-timer)
+ (set! start (SDL_GetTicks))
+ (set! state 'running))
+
+ ((stop-timer)
+ (set! state 'stopped))
+
+ ((get-time)
+ (cond ((eq? state 'stopped) 0)
+ ((eq? state 'paused) paused)
+ (else (- (SDL_GetTicks) start))))
+
+ ((get-state)
+ state)
+
+ ((pause-timer)
+ (cond ((eq? state 'running)
+ (set! paused (- (SDL_GetTicks) start))
+ (set! state 'paused))))
+
+ ((resume-timer)
+ (cond ((eq? state 'paused)
+ (set! start (- (SDL_GetTicks) paused))
+ (set! state 'running))))))))
(define (start-timer timer)
- (assoc-set! timer 'start (SDL_GetTicks))
- (assoc-set! timer state 'running))
+ (timer 'start-timer))
(define (stop-timer timer)
- (assoc-set! timer 'state 'stopped))
+ (timer 'stop-timer))
(define (get-time timer)
- (cond ((eq? (assoc 'state timer) 'stopped) 0)
- ((eq? (assoc 'state timer) 'paused) (assoc 'paused timer))
- (else (- (SDL_GetTicks) (assoc 'start timer)))))
+ (timer 'get-time))
+
+(define (get-state timer)
+ (timer 'get-state))
(define (pause-timer timer)
- (cond ((eq? (assoc 'state timer) 'running)
- (assoc-set! timer 'paused (- (SDL_GetTicks) (assoc 'start timer)))
- (assoc-set! timer 'state 'paused))))
+ (timer 'pause-timer))
(define (resume-timer timer)
- (cond ((eq? (assoc 'state timer) 'paused)
- (assoc-set! timer 'start (- (SDL_GetTicks) (assoc 'paused timer)))
- (assoc-set! timer 'state 'running))))
+ (timer 'resume-timer))