Add REDRAW signal to Kernel

Kernel.cpp

@@ -28,7 +28,6 @@ void Kernel_setup()
 {
   last_tick_start = millis();
   last_tick_duration = 0;
-  //Serial.begin(115200);
 }
 
 void Kernel_start(int (*callback)(int, unsigned int), unsigned long interval)
@@ -223,10 +222,13 @@ void Kernel_tick()
       // If the process has any non-masked signals pending, run it
       if ((tasks[i].signal & tasks[i].signal_mask) != 0)
       {
-        // Run the task
-        int task_return = (*tasks[i].callback)(tasks[i].pid, tasks[i].signal);
-        // Reset the signal
+
+        unsigned int signals = tasks[i].signal;
         tasks[i].signal = SIGNAL_NONE;
+        
+        // Run the task
+        int task_return = (*tasks[i].callback)(tasks[i].pid, signals);
+        
 
         // If the tasks's return value was non-zero, it has exited.
         if (task_return != 0)
@@ -263,7 +265,7 @@ void Kernel_tick()
   bool signals_pending = false;
   for (int i=0; i<MAX_TASKS; i++)
   {
-    if (tasks[i].signal != SIGNAL_NONE)
+    if ((tasks[i].signal & tasks[i].signal_mask) != 0)
     {
       signals_pending = true;
     }

Kernel.h

@@ -56,6 +56,7 @@ unsigned long Kernel_get_last_tick_duration();
 #define SIGNAL_STOP     0x0004
 #define SIGNAL_INPUT_A  0x0008
 #define SIGNAL_INPUT_B  0x0010
+#define SIGNAL_REDRAW   0x0020
 
 #define KERNEL_INPUT_BUTTON_A 0
 #define KERNEL_INPUT_BUTTON_B 1