1 files changed, 47 insertions, 0 deletions

diff --git a/src/utils.rkt b/src/utils.rkt
new file mode 100644
index 0000000..eaac52a
--- /dev/null
+++ b/src/utils.rkt
@@ -0,0 +1,47 @@
+#lang racket/base
+
+(require racket/place)
+
+(provide make-toggle-relay)
+(provide make-toggle-blinker-relay)
+
+(define (make-send-to-dev data)
+  (lambda (dev)
+    (with-output-to-file dev
+      #:exists 'truncate
+      #:mode 'binary
+      (lambda ()
+        (write-bytes data)))))
+
+(define send-message-on
+  (make-send-to-dev (bytes  #xA0 #x01 #x01 #xA2)))
+
+(define send-message-off
+  (make-send-to-dev (bytes  #xA0 #x01 #x00 #xA1)))
+
+(define (make-toggle-relay dev)
+  (let ((turn-on? #t))
+    (lambda ()
+      (displayln (format "Relay on ~a toggled" dev))
+      (if turn-on?
+          (send-message-on dev)
+          (send-message-off dev))
+      (set! turn-on? (not turn-on?)))))
+
+(define (make-toggle-blinker-relay toggle-relay
+                                   #:delay [delay 3])
+  (let ((blinker-thread #f))
+    (lambda ()
+      (if (and (thread? blinker-thread)
+               (not (thread-dead? blinker-thread)))
+          (if (thread-running? blinker-thread)
+              (thread-suspend blinker-thread)
+              (thread-resume blinker-thread))
+          (set! blinker-thread
+                (thread
+                 (lambda ()
+                   (let loop ()
+                     (toggle-relay)
+                     (sleep delay)
+                     (loop))))))
+      blinker-thread)))