From 7481b9c24c1268640bf2a037caddedd719a822ee Mon Sep 17 00:00:00 2001
From: Peli de Halleux <jhalleux@microsoft.com>
Date: Mon, 8 Aug 2016 16:54:43 -0700
Subject: [PATCH] call receiveNumber in onDataReceived to flush queue if needed
 (startup race) fixed simulator issue when event onDataReceived gets raised

---
 libs/microbit-radio/radio.cpp  | 27 ++++++++++++++++-----------
 libs/microbit-radio/shims.d.ts | 16 ++++++++--------
 sim/libmbit.ts                 |  1 +
 sim/state.ts                   |  5 ++---
 4 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/libs/microbit-radio/radio.cpp b/libs/microbit-radio/radio.cpp
index fb59b495..2bcbfbc0 100644
--- a/libs/microbit-radio/radio.cpp
+++ b/libs/microbit-radio/radio.cpp
@@ -134,16 +134,6 @@ namespace radio {
         uBit.serial.send("}\r\n");
     }
 
-    /**
-     * Registers code to run when a packet is received over radio.
-     */
-    //% help=radio/on-data-received
-    //% weight=50
-    //% blockId=radio_datagram_received_event block="radio on data received" blockGap=8
-    void onDataReceived(Action body) {
-        if (radioEnable() != MICROBIT_OK) return;
-        registerWithDal(MICROBIT_ID_RADIO, MICROBIT_RADIO_EVT_DATAGRAM, body);    
-    }
 
     /**
      * Reads a number at a given index, between ``0`` and ``3``, from the packet received by ``receive number``. Not supported in simulator.
@@ -162,7 +152,7 @@ namespace radio {
         }
         return 0;
     }
-
+    
     /**
      * Reads the next packet as a number from the radio queue.
      */
@@ -175,6 +165,20 @@ namespace radio {
         packet = uBit.radio.datagram.recv();
         return receivedNumberAt(0);
     }
+
+    /**
+     * Registers code to run when a packet is received over radio.
+     */
+    //% help=radio/on-data-received
+    //% weight=50
+    //% blockId=radio_datagram_received_event block="radio on data received" blockGap=8
+    void onDataReceived(Action body) {
+        if (radioEnable() != MICROBIT_OK) return;
+        registerWithDal(MICROBIT_ID_RADIO, MICROBIT_RADIO_EVT_DATAGRAM, body);    
+        // make the the receive buffer has a free spot
+        receiveNumber();
+    }
+
     
     /**
     * Reads the next packet as a string and returns it.
@@ -231,6 +235,7 @@ namespace radio {
     //% weight=8 blockGap=8
     //% blockId=radio_set_transmit_serial_number block="radio set transmit serial number %transmit"
     void setTransmitSerialNumber(bool transmit) {
+        if (radioEnable() != MICROBIT_OK) return;
         transmitSerialNumber = transmit;
     }
 }
diff --git a/libs/microbit-radio/shims.d.ts b/libs/microbit-radio/shims.d.ts
index 449ac8f1..1d27d7b7 100644
--- a/libs/microbit-radio/shims.d.ts
+++ b/libs/microbit-radio/shims.d.ts
@@ -41,14 +41,6 @@ declare namespace radio {
     //% blockId=radio_write_value_serial block="radio write value to serial" shim=radio::writeValueToSerial
     function writeValueToSerial(): void;
 
-    /**
-     * Registers code to run when a packet is received over radio.
-     */
-    //% help=radio/on-data-received
-    //% weight=50
-    //% blockId=radio_datagram_received_event block="radio on data received" blockGap=8 shim=radio::onDataReceived
-    function onDataReceived(body: () => void): void;
-
     /**
      * Reads a number at a given index, between ``0`` and ``3``, from the packet received by ``receive number``. Not supported in simulator.
      * @param index index of the number to read from 0 to 3. 1 eg
@@ -66,6 +58,14 @@ declare namespace radio {
     //% blockId=radio_datagram_receive block="radio receive number" blockGap=8 shim=radio::receiveNumber
     function receiveNumber(): number;
 
+    /**
+     * Registers code to run when a packet is received over radio.
+     */
+    //% help=radio/on-data-received
+    //% weight=50
+    //% blockId=radio_datagram_received_event block="radio on data received" blockGap=8 shim=radio::onDataReceived
+    function onDataReceived(body: () => void): void;
+
     /**
      * Reads the next packet as a string and returns it.
      */
diff --git a/sim/libmbit.ts b/sim/libmbit.ts
index 6b7d1904..d36fa5a7 100644
--- a/sim/libmbit.ts
+++ b/sim/libmbit.ts
@@ -517,6 +517,7 @@ namespace pxsim.radio {
 
     export function onDataReceived(handler: RefAction): void {
         pxt.registerWithDal(DAL.MICROBIT_ID_RADIO, DAL.MICROBIT_RADIO_EVT_DATAGRAM, handler);
+        radio.receiveNumber();
     }
 }
 
diff --git a/sim/state.ts b/sim/state.ts
index 2fced2ac..9febc82c 100644
--- a/sim/state.ts
+++ b/sim/state.ts
@@ -72,10 +72,9 @@ namespace pxsim {
         }
 
         queue(packet: PacketBuffer) {
-            if (this.datagram.length < 5) {
+            if (this.datagram.length < 4)
                 this.datagram.push(packet);
-                (<Board>runtime.board).bus.queue(DAL.MICROBIT_ID_RADIO, DAL.MICROBIT_RADIO_EVT_DATAGRAM);
-            }
+            (<Board>runtime.board).bus.queue(DAL.MICROBIT_ID_RADIO, DAL.MICROBIT_RADIO_EVT_DATAGRAM);
         }
 
         send(buffer: number[] | string) {