support for exposing device name

libs/microbit/control.cpp

@@ -155,4 +155,12 @@ namespace control {
     void onEvent(int src, int value, Action handler) { 
         registerWithDal(src, value, handler);
     }
+    
+    /**
+     * Gets a friendly name for the device derived from the its serial number
+     */
+    //% blockId="control_device_name" block="device name" weight=10
+    StringData* deviceName() {
+        return ManagedString(microbit_friendly_name()).leakData();        
+    }
 }

libs/microbit/shims.d.ts

@@ -342,6 +342,12 @@ declare namespace control {
     //% weight=20 blockGap=8 blockId="control_on_event" block="on event|from %src=control_event_source|with value %value=control_event_value" 
     //% blockExternalInputs=1 shim=control::onEvent
     function onEvent(src: number, value: number, handler: () => void): void;
+
+    /**
+     * Gets a friendly name for the device derived from the its serial number
+     */
+    //% blockId="control_device_name" block="device name" weight=10 shim=control::deviceName
+    function deviceName(): string;
 }
 
 

sim/libmbit.ts

@@ -227,6 +227,13 @@ namespace pxsim.control {
         U.userError("reset not implemented in simulator yet")
     }
     
+    export function deviceName() : string {
+        let b = board();
+        return b && b.id         
+            ? b.id.slice(0, 4) 
+            : 'abcd';
+    }
+
     export function onEvent(id: number, evid: number, handler: RefAction) {
         pxt.registerWithDal(id, evid, handler)
     }

sim/state.ts

@@ -511,7 +511,7 @@ namespace pxsim {
 
         constructor() {
             super()
-            this.id = "b" + Math.random();
+            this.id = "b" + Math.random().toString().slice(1);
             this.animationQ = new AnimationQueue(runtime);
             this.bus = new EventBus(runtime);
             this.radio = new RadioBus(runtime);