Clean up mac/radio interaction. (#538)

- Remove unnecessary calls to otPlatRadioReceive().
- Allow calls to otPlatRadioReceiveDone() whenever the radio is active.

examples/platforms/posix/radio.c

@@ -445,43 +445,35 @@ bool otPlatRadioGetPromiscuous(void)
 
 void radioReceive(void)
 {
-    if (sState != kStateTransmit || sAckWait)
+    ssize_t rval = recvfrom(sSockFd, &sReceiveMessage, sizeof(sReceiveMessage), 0, NULL, NULL);
+    assert(rval >= 0);
+
+    sReceiveFrame.mLength = (uint8_t)(rval - 1);
+
+    if (sAckWait &&
+        sTransmitFrame.mChannel == sReceiveMessage.mChannel &&
+        isFrameTypeAck(sReceiveFrame.mPsdu) &&
+        getDsn(sReceiveFrame.mPsdu) == getDsn(sTransmitFrame.mPsdu))
     {
-        ssize_t rval = recvfrom(sSockFd, &sReceiveMessage, sizeof(sReceiveMessage), 0, NULL, NULL);
-        assert(rval >= 0);
-
-        sReceiveFrame.mLength = (uint8_t)(rval - 1);
-
-        if (sAckWait &&
-            sTransmitFrame.mChannel == sReceiveMessage.mChannel &&
-            isFrameTypeAck(sReceiveFrame.mPsdu))
-        {
-            uint8_t tx_sequence = getDsn(sTransmitFrame.mPsdu);
-            uint8_t rx_sequence = getDsn(sReceiveFrame.mPsdu);
-
-            if (tx_sequence == rx_sequence)
-            {
-                sState = kStateReceive;
-                sAckWait = false;
+        sState = kStateReceive;
+        sAckWait = false;
 
 #if OPENTHREAD_ENABLE_DIAG
 
-                if (otPlatDiagModeGet())
-                {
-                    otPlatDiagRadioTransmitDone(isFramePending(sReceiveFrame.mPsdu), kThreadError_None);
-                }
-                else
-#endif
-                {
-                    otPlatRadioTransmitDone(isFramePending(sReceiveFrame.mPsdu), kThreadError_None);
-                }
-            }
-        }
-        else if (sState == kStateReceive &&
-                 sReceiveFrame.mChannel == sReceiveMessage.mChannel)
+        if (otPlatDiagModeGet())
         {
-            radioProcessFrame();
+            otPlatDiagRadioTransmitDone(isFramePending(sReceiveFrame.mPsdu), kThreadError_None);
         }
+        else
+#endif
+        {
+            otPlatRadioTransmitDone(isFramePending(sReceiveFrame.mPsdu), kThreadError_None);
+        }
+    }
+    else if ((sState == kStateReceive || sState == kStateTransmit) &&
+             (sReceiveFrame.mChannel == sReceiveMessage.mChannel))
+    {
+        radioProcessFrame();
     }
 }
 

src/core/mac/mac.cpp

@@ -192,6 +192,7 @@ bool Mac::GetRxOnWhenIdle(void) const
 void Mac::SetRxOnWhenIdle(bool aRxOnWhenIdle)
 {
     mRxOnWhenIdle = aRxOnWhenIdle;
+    NextOperation();
 }
 
 const ExtAddress *Mac::GetExtAddress(void) const
@@ -1019,8 +1020,6 @@ exit:
             break;
         }
     }
-
-    NextOperation();
 }
 
 ThreadError Mac::HandleMacCommand(Frame &aFrame)