microbit: BUGFIX - post merge fixes

- MicroBitDisplay::scroll() timing bug
  - MicroBitDisplay::print() timing bug
  - MicroBitFiber wait/notify bug

source/MicroBitDisplay.cpp

@@ -314,6 +314,7 @@ void MicroBitDisplay::updateAnimateImage()
     if (scrollingImagePosition <= -scrollingImage.getWidth() + (MICROBIT_DISPLAY_WIDTH + scrollingImageStride) && scrollingImageRendered)
     {
         animationMode = ANIMATION_MODE_NONE;  
+        this->clear();
         this->sendAnimationCompleteEvent();     
         return;
     }
@@ -566,6 +567,8 @@ void MicroBitDisplay::scrollAsync(ManagedString s, int delay)
         scrollingChar = 0;
         scrollingText = s;
 
+        animationDelay = delay;
+        animationTick = 0;
         animationMode = ANIMATION_MODE_SCROLL_TEXT;
     }
 }
@@ -592,11 +595,13 @@ void MicroBitDisplay::scrollAsync(MicroBitImage image, int delay, int stride)
         if(delay <= 0 )
             delay = MICROBIT_DEFAULT_SCROLL_SPEED;
 
-        this->scrollingImagePosition = stride < 0 ? width : -image.getWidth();
-        this->scrollingImageStride = stride;
-        this->scrollingImage = image;
-        this->scrollingImageRendered = false;
+        scrollingImagePosition = stride < 0 ? width : -image.getWidth();
+        scrollingImageStride = stride;
+        scrollingImage = image;
+        scrollingImageRendered = false;
 
+        animationDelay = delay;
+        animationTick = 0;
         animationMode = ANIMATION_MODE_SCROLL_IMAGE;
     }
 }
@@ -692,15 +697,14 @@ void MicroBitDisplay::animateAsync(MicroBitImage image, int delay, int stride, i
         if(delay <= 0 )
             delay = MICROBIT_DEFAULT_SCROLL_SPEED;
 
-        animationDelay = delay;
-        animationTick = delay-1;
-
         //calculate starting position which is offset by the stride
         scrollingImagePosition = (startingPosition == MICROBIT_DISPLAY_ANIMATE_DEFAULT_POS) ? MICROBIT_DISPLAY_WIDTH + stride : startingPosition; 
         scrollingImageStride = stride;
         scrollingImage = image;
         scrollingImageRendered = false;
 
+        animationDelay = delay;
+        animationTick = delay-1;
         animationMode = ANIMATION_MODE_ANIMATE_IMAGE;
     }
 }

source/MicroBitFiber.cpp

@@ -163,6 +163,10 @@ void scheduler_init()
     idleFiber->tcb.SP = CORTEX_M0_STACK_BASE - 0x04;    
     idleFiber->tcb.LR = (uint32_t) &idle_task;
 
+    // Register to receive events in the NOTIFY channel - this is used to implement wait-notify semantics
+    uBit.MessageBus.listen(MICROBIT_ID_NOTIFY, MICROBIT_EVT_ANY, scheduler_event, MESSAGE_BUS_LISTENER_IMMEDIATE);
+    uBit.MessageBus.listen(MICROBIT_ID_NOTIFY_ONE, MICROBIT_EVT_ANY, scheduler_event, MESSAGE_BUS_LISTENER_IMMEDIATE);
+
     // Flag that we now have a scheduler running
     uBit.flags |= MICROBIT_FLAG_SCHEDULER_RUNNING;
 }
@@ -236,7 +240,8 @@ void scheduler_event(MicroBitEvent evt)
     }
 
     // Unregister this event, as we've woken up all the fibers with this match.
-    uBit.MessageBus.ignore(evt.source, evt.value, scheduler_event);
+    if (evt.source != MICROBIT_ID_NOTIFY && evt.source != MICROBIT_ID_NOTIFY_ONE)
+        uBit.MessageBus.ignore(evt.source, evt.value, scheduler_event);
 }
 
 
@@ -320,7 +325,9 @@ void fiber_wait_for_event(uint16_t id, uint16_t value)
     queue_fiber(f, &waitQueue);
     
     // Register to receive this event, so we can wake up the fiber when it happens.
-    uBit.MessageBus.listen(id, value, scheduler_event, MESSAGE_BUS_LISTENER_IMMEDIATE);
+    // Special case for teh notify channel, as we always stay registered for that.
+    if (id != MICROBIT_ID_NOTIFY && id != MICROBIT_ID_NOTIFY_ONE)
+        uBit.MessageBus.listen(id, value, scheduler_event, MESSAGE_BUS_LISTENER_IMMEDIATE);
 
     // Finally, enter the scheduler.
     schedule();