Add setLoopTimestamp()

Author: PeterJohnson

wpilibc/src/main/native/cpp/TimedRobot.cpp

@@ -46,7 +46,7 @@ void TimedRobot::StartCompetition() {
     if (currentTime.count() == 0 || status != 0) {
       break;
     }
-    Timer::s_loopTimestamp = currentTime;
+    Timer::SetLoopTimestamp(currentTime);
 
     callback.func();
 

wpilibc/src/main/native/include/frc/Timer.h

@@ -34,8 +34,6 @@ units::second_t GetTime();
  * the timer so Get() won't return a negative duration.
  */
 class Timer {
-  friend class TimedRobot;
-
  public:
   /**
    * Create a new timer object.
@@ -132,16 +130,27 @@ class Timer {
 
   /**
    * Return the system clock time in seconds for the start of the current
-   * periodic loop. This is in the same time base as getFPGATimestamp(), but is
+   * periodic loop. This is in the same time base as GetFPGATimestamp(), but is
    * stable through a loop. This value is only valid for robot programs that use
    * TimedRobot. It is updated at the beginning of every periodic callback
-   * (including the normal periodic loop).
+   * (including the normal periodic loop). Calling this from threads other than
+   * than the main periodic loop has undefined behavior.
    *
    * @return Robot running time in seconds, as of the start of the current
    * periodic function.
    */
   static units::second_t GetLoopTimestamp() { return s_loopTimestamp; }
 
+  /**
+   * Sets the timestamp returned by GetLoopTimestamp(). Intended for library
+   * use; calling this from team code may result in unexpected behavior.
+   *
+   * @param timestamp timestamp in seconds
+   */
+  static void SetLoopTimestamp(units::second_t timestamp) {
+    s_loopTimestamp = timestamp;
+  }
+
   /**
    * Return the approximate match time.
    *

wpilibj/src/main/java/edu/wpi/first/wpilibj/TimedRobot.java

@@ -127,7 +127,7 @@ public void startCompetition() {
       if (currentTime == 0) {
         break;
       }
-      Timer.s_loopTimestamp = currentTime / 1000000.0;
+      Timer.setLoopTimestamp(currentTime / 1000000.0);
 
       callback.func.run();
 

wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java

@@ -11,7 +11,7 @@
  * get() won't return a negative duration.
  */
 public class Timer {
-  static double s_loopTimestamp;
+  private static double s_loopTimestamp;
 
   /**
    * Return the system clock time in seconds. Return the time from the FPGA hardware clock in
@@ -27,14 +27,25 @@ public static double getFPGATimestamp() {
    * Return the system clock time in seconds for the start of the current periodic loop. This is
    * in the same time base as getFPGATimestamp(), but is stable through a loop. This value is only
    * valid for robot programs that use TimedRobot. It is updated at the beginning of every periodic
-   * callback (including the normal periodic loop).
+   * callback (including the normal periodic loop). Calling this from threads other than than the
+   * main periodic loop has undefined behavior.
    *
    * @return Robot running time in seconds, as of the start of the current periodic function.
    */
   public static double getLoopTimestamp() {
     return s_loopTimestamp;
   }
 
+  /**
+   * Sets the timestamp returned by getLoopTimestamp(). Intended for library use; calling this from
+   * team code may result in unexpected behavior.
+   *
+   * @param timestamp timestamp in seconds
+   */
+  public static void setLoopTimestamp(double timestamp) {
+    s_loopTimestamp = timestamp;
+  }
+
   /**
    * Return the approximate match time. The FMS does not send an official match time to the robots,
    * but does send an approximate match time. The value will count down the time remaining in the