Add API function to check if MAC layer is during transmission operation. (#1447)

include/openthread/link.h

@@ -136,6 +136,20 @@ OTAPI bool OTCALL otLinkIsEnergyScanInProgress(otInstance *aInstance);
  */
 OTAPI ThreadError OTCALL otLinkSendDataRequest(otInstance *aInstance);
 
+/**
+ * This function indicates whether or not an IEEE 802.15.4 MAC is in the transmit state.
+ *
+ * MAC module is in the transmit state during CSMA/CA procedure, CCA, Data, Beacon or Data Request frame transmission
+ * and receiving an ACK of a transmitted frame. MAC module is not in the transmit state during transmission of an ACK
+ * frame or a Beacon Request frame.
+ *
+ * @param[in] aInstance A pointer to an OpenThread instance.
+ *
+ * @returns true if an IEEE 802.15.4 MAC is in the transmit state, false otherwise.
+ *
+ */
+OTAPI bool OTCALL otLinkIsInTransmitState(otInstance *aInstance);
+
 /**
  * Get the IEEE 802.15.4 channel.
  *

src/core/api/link_api.cpp

@@ -355,6 +355,10 @@ bool otLinkIsEnergyScanInProgress(otInstance *aInstance)
     return aInstance->mThreadNetif.GetMac().IsEnergyScanInProgress();
 }
 
+bool otLinkIsInTransmitState(otInstance *aInstance)
+{
+    return aInstance->mThreadNetif.GetMac().IsInTransmitState();
+}
 
 
 #ifdef __cplusplus

src/core/mac/mac.cpp

@@ -257,6 +257,11 @@ bool Mac::IsEnergyScanInProgress(void)
     return (mState == kStateEnergyScan) || (mPendingScanRequest == kScanTypeEnergy);
 }
 
+bool Mac::IsInTransmitState(void)
+{
+    return (mState == kStateTransmitData) || (mState == kStateTransmitBeacon);
+}
+
 void Mac::StartEnergyScan(void)
 {
     mState = kStateEnergyScan;

src/core/mac/mac.hpp

@@ -502,6 +502,16 @@ public:
      */
     bool IsEnergyScanInProgress(void);
 
+    /**
+     * This method returns if the MAC layer is in transmit state.
+     *
+     * The MAC layer is in transmit state during CSMA/CA, CCA, transmission of Data, Beacon or Data Request frames and
+     * receiving of ACK frames. The MAC layer is not in transmit state during transmission of ACK frames or Beacon
+     * Requests.
+     *
+     */
+    bool IsInTransmitState(void);
+
     /**
      * This method registers a callback to provide received raw IEEE 802.15.4 frames.
      *