Added an exception check when the game is close to overflowing. Fixes the fifo overflow that occurs in Battalion Wars 2.

Changed the CPEnd loop check to an exact match.

Source/Core/VideoCommon/CommandProcessor.cpp

@@ -330,7 +330,7 @@ void GatherPipeBursted()
 	}
 
 	// update the fifo pointer
-	if (fifo.CPWritePointer >= fifo.CPEnd)
+	if (fifo.CPWritePointer == fifo.CPEnd)
 		fifo.CPWritePointer = fifo.CPBase;
 	else
 		fifo.CPWritePointer += GATHER_PIPE_SIZE;
@@ -342,6 +342,10 @@ void GatherPipeBursted()
 		ProcessorInterface::Fifo_CPUEnd = fifo.CPEnd;
 	}
 
+	// If the game is running close to overflowing, make the exception checking more frequent.
+	if (fifo.bFF_HiWatermark)
+		CoreTiming::ForceExceptionCheck(0);
+
 	Common::AtomicAdd(fifo.CPReadWriteDistance, GATHER_PIPE_SIZE);
 
 	RunGpu();
@@ -470,8 +474,7 @@ void ProcessFifoAllDistance()
 {
 	if (IsOnThread())
 	{
-		while (!interruptWaiting && fifo.bFF_GPReadEnable &&
-			fifo.CPReadWriteDistance && !AtBreakpoint())
+		while (!interruptWaiting && fifo.bFF_GPReadEnable && fifo.CPReadWriteDistance && !AtBreakpoint())
 			Common::YieldCPU();
 	}
 }