From 4b76adf15bdc0d747bfc59bd06ed8aa4501c29a6 Mon Sep 17 00:00:00 2001
From: sciencewhiz <sciencewhiz@users.noreply.github.com>
Date: Mon, 8 Jun 2020 10:37:27 -0700
Subject: [PATCH] [wpilibc] Remove incorrect timer rollover (#2523)

If the 64 bit FPGA timer rolls over, a 32 bit value is added for
the rollover, an artifact of when it was a 32 bit timer.
The 64 bit microsecond timer won't rollover for 500k years so remove the
check for simplicity.
Fixes #2504
---
 wpilibc/src/main/native/cpp/Timer.cpp        |  4 +---
 wpilibc/src/main/native/cpp/frc2/Timer.cpp   | 10 ----------
 wpilibc/src/main/native/include/frc/Timer.h  |  5 +----
 wpilibc/src/main/native/include/frc2/Timer.h |  3 ---
 4 files changed, 2 insertions(+), 20 deletions(-)

diff --git a/wpilibc/src/main/native/cpp/Timer.cpp b/wpilibc/src/main/native/cpp/Timer.cpp
index c91bc13c1f..fb6f6144e2 100644
--- a/wpilibc/src/main/native/cpp/Timer.cpp
+++ b/wpilibc/src/main/native/cpp/Timer.cpp
@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2008-2019 FIRST. All Rights Reserved.                        */
+/* Copyright (c) 2008-2020 FIRST. All Rights Reserved.                        */
 /* Open Source Software - may be modified and shared by FRC teams. The code   */
 /* must be accompanied by the FIRST BSD license file in the root directory of */
 /* the project.                                                               */
@@ -25,8 +25,6 @@ double GetTime() { return frc2::GetTime().to<double>(); }
 
 using namespace frc;
 
-const double Timer::kRolloverTime = frc2::Timer::kRolloverTime.to<double>();
-
 Timer::Timer() { Reset(); }
 
 double Timer::Get() const { return m_timer.Get().to<double>(); }
diff --git a/wpilibc/src/main/native/cpp/frc2/Timer.cpp b/wpilibc/src/main/native/cpp/frc2/Timer.cpp
index b54dc485c7..8350115b53 100644
--- a/wpilibc/src/main/native/cpp/frc2/Timer.cpp
+++ b/wpilibc/src/main/native/cpp/frc2/Timer.cpp
@@ -36,9 +36,6 @@ units::second_t GetTime() {
 
 using namespace frc2;
 
-// for compatibility with msvc12--see C2864
-const units::second_t Timer::kRolloverTime = units::second_t((1ll << 32) / 1e6);
-
 Timer::Timer() { Reset(); }
 
 Timer::Timer(const Timer& rhs)
@@ -77,13 +74,6 @@ units::second_t Timer::Get() const {
 
   std::scoped_lock lock(m_mutex);
   if (m_running) {
-    // If the current time is before the start time, then the FPGA clock 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 {
     result = m_accumulatedTime;
diff --git a/wpilibc/src/main/native/include/frc/Timer.h b/wpilibc/src/main/native/include/frc/Timer.h
index 99caa4770f..990e8789ec 100644
--- a/wpilibc/src/main/native/include/frc/Timer.h
+++ b/wpilibc/src/main/native/include/frc/Timer.h
@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2008-2019 FIRST. All Rights Reserved.                        */
+/* Copyright (c) 2008-2020 FIRST. All Rights Reserved.                        */
 /* Open Source Software - may be modified and shared by FRC teams. The code   */
 /* must be accompanied by the FIRST BSD license file in the root directory of */
 /* the project.                                                               */
@@ -132,9 +132,6 @@ class Timer {
    */
   static double GetMatchTime();
 
-  // The time, in seconds, at which the 32-bit FPGA timestamp rolls over to 0
-  static const double kRolloverTime;
-
  private:
   frc2::Timer m_timer;
 };
diff --git a/wpilibc/src/main/native/include/frc2/Timer.h b/wpilibc/src/main/native/include/frc2/Timer.h
index 9c616fa02b..4994f97485 100644
--- a/wpilibc/src/main/native/include/frc2/Timer.h
+++ b/wpilibc/src/main/native/include/frc2/Timer.h
@@ -144,9 +144,6 @@ class Timer {
    */
   static units::second_t GetMatchTime();
 
-  // The time, in seconds, at which the 32-bit FPGA timestamp rolls over to 0
-  static const units::second_t kRolloverTime;
-
  private:
   units::second_t m_startTime = 0_s;
   units::second_t m_accumulatedTime = 0_s;