Transceiver52M: Separate main transmit and receive drive threads

This patch primarily addresses observed repeated overrun
conditions in embedded environments - namely ARM.

The heartbeat of the transceiver is derived from the receive
sample stream, which drives the main GSM clock. Detach the
transmit thread from the receive loop to avoid interfering with
the receive I/O, which is sensitive to overrun conditions if
pull process is interrupted.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

2 files changed, 24 insertions, 15 deletions

diff --git a/Transceiver52M/Transceiver.cpp b/Transceiver52M/Transceiver.cpp
index 0a515b1..03aa3c1 100644
--- a/Transceiver52M/Transceiver.cpp
+++ b/Transceiver52M/Transceiver.cpp
@@ -59,7 +59,8 @@ Transceiver::Transceiver(int wBasePort,
 {
   GSM::Time startTime(random() % gHyperframe,0);
 
-  mFIFOServiceLoopThread = new Thread(32768);  ///< thread to push bursts into transmit FIFO
+  mRxServiceLoopThread = new Thread(32768);
+  mTxServiceLoopThread = new Thread(32768);
   mControlServiceLoopThread = new Thread(32768);       ///< thread to process control messages from GSM core
   mTransmitPriorityQueueServiceLoopThread = new Thread(32768);///< thread to process transmit bursts from GSM core
 
@@ -504,7 +505,8 @@ void Transceiver::driveControl()
         mRadioInterface->start();
 
         // Start radio interface threads.
-        mFIFOServiceLoopThread->start((void * (*)(void*))FIFOServiceLoopAdapter,(void*) this);
+        mTxServiceLoopThread->start((void * (*)(void*))TxServiceLoopAdapter,(void*) this);
+        mRxServiceLoopThread->start((void * (*)(void*))RxServiceLoopAdapter,(void*) this);
         mTransmitPriorityQueueServiceLoopThread->start((void * (*)(void*))TransmitPriorityQueueServiceLoopAdapter,(void*) this);
         writeClockInterface();
 
@@ -768,11 +770,9 @@ void Transceiver::driveTransmitFIFO()
       pushRadioVector(mTransmitDeadlineClock);
       mTransmitDeadlineClock.incTN();
     }
-    
   }
-  // FIXME -- This should not be a hard spin.
-  // But any delay here causes us to throw omni_thread_fatal.
-  //else radioClock->wait();
+
+  radioClock->wait();
 }
 
 
@@ -789,17 +789,22 @@ void Transceiver::writeClockInterface()
 
   mLastClockUpdateTime = mTransmitDeadlineClock;
 
-}   
-  
-
-
+}
 
-void *FIFOServiceLoopAdapter(Transceiver *transceiver)
+void *RxServiceLoopAdapter(Transceiver *transceiver)
 {
   transceiver->setPriority();
 
   while (1) {
     transceiver->driveReceiveFIFO();
+    pthread_testcancel();
+  }
+  return NULL;
+}
+
+void *TxServiceLoopAdapter(Transceiver *transceiver)
+{
+  while (1) {
     transceiver->driveTransmitFIFO();
     pthread_testcancel();
   }
diff --git a/Transceiver52M/Transceiver.h b/Transceiver52M/Transceiver.h
index 3175213..3e4f784 100644
--- a/Transceiver52M/Transceiver.h
+++ b/Transceiver52M/Transceiver.h
@@ -56,7 +56,8 @@ private:
   VectorFIFO*  mTransmitFIFO;     ///< radioInterface FIFO of transmit bursts 
   VectorFIFO*  mReceiveFIFO;      ///< radioInterface FIFO of receive bursts 
 
-  Thread *mFIFOServiceLoopThread;  ///< thread to push/pull bursts into transmit/receive FIFO
+  Thread *mRxServiceLoopThread;   ///< thread to pull bursts into receive FIFO
+  Thread *mTxServiceLoopThread;   ///< thread to push bursts into transmit FIFO
   Thread *mControlServiceLoopThread;       ///< thread to process control messages from GSM core
   Thread *mTransmitPriorityQueueServiceLoopThread;///< thread to process transmit bursts from GSM core
 
@@ -191,7 +192,9 @@ protected:
   */
   bool driveTransmitPriorityQueue();
 
-  friend void *FIFOServiceLoopAdapter(Transceiver *);
+  friend void *RxServiceLoopAdapter(Transceiver *);
+
+  friend void *TxServiceLoopAdapter(Transceiver *);
 
   friend void *ControlServiceLoopAdapter(Transceiver *);
 
@@ -204,8 +207,9 @@ protected:
 
 };
 
-/** FIFO thread loop */
-void *FIFOServiceLoopAdapter(Transceiver *);
+/** Main drive threads */
+void *RxServiceLoopAdapter(Transceiver *);
+void *TxServiceLoopAdapter(Transceiver *);
 
 /** control message handler thread loop */
 void *ControlServiceLoopAdapter(Transceiver *);