Fixed a few more small TODOs

Timer::Get now compensates for the FPGA time rolling over after 71 minutes

UltraSonic::Ping doesn't bother disabling automatic mode, since it asserts
that it's not in automatic mode on the line before.

Change-Id: I6b0f45327c453abd8a846ec8da0f9676e210d909

wpilibc/wpilibC++/lib/Timer.cpp

@@ -11,6 +11,10 @@
 #include "HAL/HAL.hpp"
 #include "HAL/cpp/Synchronized.hpp"
 #include "Utility.h"
+#include <iostream>
+
+// The time, in seconds, at which the 32-bit FPGA timestamp rolls over to 0
+static const double kRolloverTime = (1ll << 32) / 1e6;
 
 /**
  * Pause the task for a specified time.
@@ -89,8 +93,13 @@ double Timer::Get()
 	Synchronized sync(m_semaphore);
 	if(m_running)
 	{
-		// This math won't work if the timer rolled over (71 minutes after boot).
+		// If the current time is before the start time, then the FPGA clock
-		// TODO: Check for it and compensate.
+		// rolled over.  Compensate by adding the ~71 minutes that it takes
+		// to roll over to the current time.
+		if(currentTime < m_startTime) {
+			currentTime += kRolloverTime;
+		}
+
 		result = (currentTime - m_startTime) + m_accumulatedTime;
 	}
 	else

wpilibc/wpilibC++/lib/Ultrasonic.cpp

@@ -230,9 +230,7 @@ void Ultrasonic::SetAutomaticMode(bool enabling)
  */
 void Ultrasonic::Ping()
 {
-	// TODO: Either assert or disable, not both.
 	wpi_assert(!m_automaticEnabled);
-	SetAutomaticMode(false); // turn off automatic round robin if pinging single sensor
 	m_counter->Reset(); // reset the counter to zero (invalid data now)
 	m_pingChannel->Pulse(kPingTime); // do the ping to start getting a single range
 }