Merge commit '849ebe917b82f5099633e6b5a915d550e76bc6bc' into HEAD

Change-Id: Ib317023b5d8bffb49eb4e05c49f635e094a88e63
diff --git a/frc971/wpilib/ahal/Counter.h b/frc971/wpilib/ahal/Counter.h
index 26ae7a2..b2c6ecb 100644
--- a/frc971/wpilib/ahal/Counter.h
+++ b/frc971/wpilib/ahal/Counter.h
@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) FIRST 2008-2017. All Rights Reserved.                        */
+/* Copyright (c) 2008-2019 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.                                                               */
@@ -30,6 +30,9 @@
  * to be zeroed before use.
  */
 class Counter : public CounterBase {
+  friend class DMA;
+  friend class DMASample;
+
  public:
   enum Mode {
     kTwoPulse = 0,
@@ -37,68 +40,395 @@
     kPulseLength = 2,
     kExternalDirection = 3
   };
+
+  /**
+   * Create an instance of a counter where no sources are selected.
+   *
+   * They all must be selected by calling functions to specify the upsource and
+   * the downsource independently.
+   *
+   * This creates a ChipObject counter and initializes status variables
+   * appropriately.
+   *
+   * The counter will start counting immediately.
+   *
+   * @param mode The counter mode
+   */
   explicit Counter(Mode mode = kTwoPulse);
+
+  /**
+   * Create an instance of a Counter object.
+   *
+   * Create an up-Counter instance given a channel.
+   *
+   * The counter will start counting immediately.
+   *
+   * @param channel The DIO channel to use as the up source. 0-9 are on-board,
+   *                10-25 are on the MXP
+   */
   explicit Counter(int channel);
-  explicit Counter(DigitalSource *source);
+
+  /**
+   * Create an instance of a counter from a Digital Source (such as a Digital
+   * Input).
+   *
+   * This is used if an existing digital input is to be shared by multiple other
+   * objects such as encoders or if the Digital Source is not a Digital Input
+   * channel (such as an Analog Trigger).
+   *
+   * The counter will start counting immediately.
+   * @param source A pointer to the existing DigitalSource object. It will be
+   *               set as the Up Source.
+   */
+  explicit Counter(DigitalSource* source);
+
+  /**
+   * Create an instance of a counter from a Digital Source (such as a Digital
+   * Input).
+   *
+   * This is used if an existing digital input is to be shared by multiple other
+   * objects such as encoders or if the Digital Source is not a Digital Input
+   * channel (such as an Analog Trigger).
+   *
+   * The counter will start counting immediately.
+   *
+   * @param source A pointer to the existing DigitalSource object. It will be
+   *               set as the Up Source.
+   */
   explicit Counter(std::shared_ptr<DigitalSource> source);
-  explicit Counter(const AnalogTrigger &trigger);
-  Counter(EncodingType encodingType, DigitalSource *upSource,
-          DigitalSource *downSource, bool inverted);
+
+  /**
+   * Create an instance of a Counter object.
+   *
+   * Create an instance of a simple up-Counter given an analog trigger.
+   * Use the trigger state output from the analog trigger.
+   *
+   * The counter will start counting immediately.
+   *
+   * @param trigger The reference to the existing AnalogTrigger object.
+   */
+  explicit Counter(const AnalogTrigger& trigger);
+
+  /**
+   * Create an instance of a Counter object.
+   *
+   * Creates a full up-down counter given two Digital Sources.
+   *
+   * @param encodingType The quadrature decoding mode (1x or 2x)
+   * @param upSource     The pointer to the DigitalSource to set as the up
+   *                     source
+   * @param downSource   The pointer to the DigitalSource to set as the down
+   *                     source
+   * @param inverted     True to invert the output (reverse the direction)
+   */
+  Counter(EncodingType encodingType, DigitalSource* upSource,
+          DigitalSource* downSource, bool inverted);
+
+  /**
+   * Create an instance of a Counter object.
+   *
+   * Creates a full up-down counter given two Digital Sources.
+   *
+   * @param encodingType The quadrature decoding mode (1x or 2x)
+   * @param upSource     The pointer to the DigitalSource to set as the up
+   *                     source
+   * @param downSource   The pointer to the DigitalSource to set as the down
+   *                     source
+   * @param inverted     True to invert the output (reverse the direction)
+   */
   Counter(EncodingType encodingType, std::shared_ptr<DigitalSource> upSource,
           std::shared_ptr<DigitalSource> downSource, bool inverted);
-  virtual ~Counter();
 
+  ~Counter() override;
+
+  Counter(Counter&&) = default;
+  Counter& operator=(Counter&&) = default;
+
+  /**
+   * Set the upsource for the counter as a digital input channel.
+   *
+   * @param channel The DIO channel to use as the up source. 0-9 are on-board,
+   *                10-25 are on the MXP
+   */
   void SetUpSource(int channel);
-  void SetUpSource(AnalogTrigger *analogTrigger, AnalogTriggerType triggerType);
+
+  /**
+   * Set the up counting source to be an analog trigger.
+   *
+   * @param analogTrigger The analog trigger object that is used for the Up
+   *                      Source
+   * @param triggerType   The analog trigger output that will trigger the
+   *                      counter.
+   */
+  void SetUpSource(AnalogTrigger* analogTrigger, AnalogTriggerType triggerType);
+
+  /**
+   * Set the up counting source to be an analog trigger.
+   *
+   * @param analogTrigger The analog trigger object that is used for the Up
+   *                      Source
+   * @param triggerType   The analog trigger output that will trigger the
+   *                      counter.
+   */
   void SetUpSource(std::shared_ptr<AnalogTrigger> analogTrigger,
                    AnalogTriggerType triggerType);
-  void SetUpSource(DigitalSource *source);
+
+  void SetUpSource(DigitalSource* source);
+
+  /**
+   * Set the source object that causes the counter to count up.
+   *
+   * Set the up counting DigitalSource.
+   *
+   * @param source Pointer to the DigitalSource object to set as the up source
+   */
   void SetUpSource(std::shared_ptr<DigitalSource> source);
-  void SetUpSource(DigitalSource &source);
+
+  /**
+   * Set the source object that causes the counter to count up.
+   *
+   * Set the up counting DigitalSource.
+   *
+   * @param source Reference to the DigitalSource object to set as the up source
+   */
+  void SetUpSource(DigitalSource& source);
+
+  /**
+   * Set the edge sensitivity on an up counting source.
+   *
+   * Set the up source to either detect rising edges or falling edges or both.
+   *
+   * @param risingEdge  True to trigger on rising edges
+   * @param fallingEdge True to trigger on falling edges
+   */
   void SetUpSourceEdge(bool risingEdge, bool fallingEdge);
+
+  /**
+   * Disable the up counting source to the counter.
+   */
   void ClearUpSource();
 
+  /**
+   * Set the down counting source to be a digital input channel.
+   *
+   * @param channel The DIO channel to use as the up source. 0-9 are on-board,
+   *                10-25 are on the MXP
+   */
   void SetDownSource(int channel);
-  void SetDownSource(AnalogTrigger *analogTrigger,
+
+  /**
+   * Set the down counting source to be an analog trigger.
+   *
+   * @param analogTrigger The analog trigger object that is used for the Down
+   *                      Source
+   * @param triggerType   The analog trigger output that will trigger the
+   *                      counter.
+   */
+  void SetDownSource(AnalogTrigger* analogTrigger,
                      AnalogTriggerType triggerType);
+
+  /**
+   * Set the down counting source to be an analog trigger.
+   *
+   * @param analogTrigger The analog trigger object that is used for the Down
+   *                      Source
+   * @param triggerType   The analog trigger output that will trigger the
+   *                      counter.
+   */
   void SetDownSource(std::shared_ptr<AnalogTrigger> analogTrigger,
                      AnalogTriggerType triggerType);
-  void SetDownSource(DigitalSource *source);
+
+  /**
+   * Set the source object that causes the counter to count down.
+   *
+   * Set the down counting DigitalSource.
+   *
+   * @param source Pointer to the DigitalSource object to set as the down source
+   */
+  void SetDownSource(DigitalSource* source);
+
+  /**
+   * Set the source object that causes the counter to count down.
+   *
+   * Set the down counting DigitalSource.
+   *
+   * @param source Reference to the DigitalSource object to set as the down
+   *               source
+   */
+  void SetDownSource(DigitalSource& source);
+
   void SetDownSource(std::shared_ptr<DigitalSource> source);
-  void SetDownSource(DigitalSource &source);
+
+  /**
+   * Set the edge sensitivity on a down counting source.
+   *
+   * Set the down source to either detect rising edges or falling edges.
+   *
+   * @param risingEdge  True to trigger on rising edges
+   * @param fallingEdge True to trigger on falling edges
+   */
   void SetDownSourceEdge(bool risingEdge, bool fallingEdge);
+
+  /**
+   * Disable the down counting source to the counter.
+   */
   void ClearDownSource();
 
+  /**
+   * Set standard up / down counting mode on this counter.
+   *
+   * Up and down counts are sourced independently from two inputs.
+   */
   void SetUpDownCounterMode();
+
+  /**
+   * Set external direction mode on this counter.
+   *
+   * Counts are sourced on the Up counter input.
+   * The Down counter input represents the direction to count.
+   */
   void SetExternalDirectionMode();
+
+  /**
+   * Set Semi-period mode on this counter.
+   *
+   * Counts up on both rising and falling edges.
+   */
   void SetSemiPeriodMode(bool highSemiPeriod);
+
+  /**
+   * Configure the counter to count in up or down based on the length of the
+   * input pulse.
+   *
+   * This mode is most useful for direction sensitive gear tooth sensors.
+   *
+   * @param threshold The pulse length beyond which the counter counts the
+   *                  opposite direction. Units are seconds.
+   */
   void SetPulseLengthMode(double threshold);
 
+  /**
+   * Set the Counter to return reversed sensing on the direction.
+   *
+   * This allows counters to change the direction they are counting in the case
+   * of 1X and 2X quadrature encoding only. Any other counter mode isn't
+   * supported.
+   *
+   * @param reverseDirection true if the value counted should be negated.
+   */
   void SetReverseDirection(bool reverseDirection);
 
-  // CounterBase interface
-  int Get() const override;
-  void Reset() override;
-  double GetPeriod() const override;
-  void SetMaxPeriod(double maxPeriod) override;
-  void SetUpdateWhenEmpty(bool enabled);
-  bool GetStopped() const override;
-  bool GetDirection() const override;
-
+  /**
+   * Set the Samples to Average which specifies the number of samples of the
+   * timer to average when calculating the period. Perform averaging to account
+   * for mechanical imperfections or as oversampling to increase resolution.
+   *
+   * @param samplesToAverage The number of samples to average from 1 to 127.
+   */
   void SetSamplesToAverage(int samplesToAverage);
+
+  /**
+   * Get the Samples to Average which specifies the number of samples of the
+   * timer to average when calculating the period.
+   *
+   * Perform averaging to account for mechanical imperfections or as
+   * oversampling to increase resolution.
+   *
+   * @return The number of samples being averaged (from 1 to 127)
+   */
   int GetSamplesToAverage() const;
-  int GetFPGAIndex() const { return m_index; }
+
+  int GetFPGAIndex() const;
+
+  // CounterBase interface
+  /**
+   * Read the current counter value.
+   *
+   * Read the value at this instant. It may still be running, so it reflects the
+   * current value. Next time it is read, it might have a different value.
+   */
+  int Get() const override;
+
+  /**
+   * Reset the Counter to zero.
+   *
+   * Set the counter value to zero. This doesn't effect the running state of the
+   * counter, just sets the current value to zero.
+   */
+  void Reset() override;
+
+  /**
+   * Get the Period of the most recent count.
+   *
+   * Returns the time interval of the most recent count. This can be used for
+   * velocity calculations to determine shaft speed.
+   *
+   * @returns The period between the last two pulses in units of seconds.
+   */
+  double GetPeriod() const override;
+
+  /**
+   * Set the maximum period where the device is still considered "moving".
+   *
+   * Sets the maximum period where the device is considered moving. This value
+   * is used to determine the "stopped" state of the counter using the
+   * GetStopped method.
+   *
+   * @param maxPeriod The maximum period where the counted device is considered
+   *                  moving in seconds.
+   */
+  void SetMaxPeriod(double maxPeriod) override;
+
+  /**
+   * Select whether you want to continue updating the event timer output when
+   * there are no samples captured.
+   *
+   * The output of the event timer has a buffer of periods that are averaged and
+   * posted to a register on the FPGA.  When the timer detects that the event
+   * source has stopped (based on the MaxPeriod) the buffer of samples to be
+   * averaged is emptied.  If you enable the update when empty, you will be
+   * notified of the stopped source and the event time will report 0 samples.
+   * If you disable update when empty, the most recent average will remain on
+   * the output until a new sample is acquired.  You will never see 0 samples
+   * output (except when there have been no events since an FPGA reset) and you
+   * will likely not see the stopped bit become true (since it is updated at the
+   * end of an average and there are no samples to average).
+   *
+   * @param enabled True to enable update when empty
+   */
+  void SetUpdateWhenEmpty(bool enabled);
+
+  /**
+   * Determine if the clock is stopped.
+   *
+   * Determine if the clocked input is stopped based on the MaxPeriod value set
+   * using the SetMaxPeriod method. If the clock exceeds the MaxPeriod, then the
+   * device (and counter) are assumed to be stopped and it returns true.
+   *
+   * @return Returns true if the most recent counter period exceeds the
+   *         MaxPeriod value set by SetMaxPeriod.
+   */
+  bool GetStopped() const override;
+
+  /**
+   * The last direction the counter value changed.
+   *
+   * @return The last direction the counter value changed.
+   */
+  bool GetDirection() const override;
 
  protected:
   // Makes the counter count up.
   std::shared_ptr<DigitalSource> m_upSource;
+
   // Makes the counter count down.
   std::shared_ptr<DigitalSource> m_downSource;
+
   // The FPGA counter object
-  HAL_CounterHandle m_counter = HAL_kInvalidHandle;
+  hal::Handle<HAL_CounterHandle> m_counter;
 
  private:
-  int m_index = 0;  ///< The index of this counter.
+  int m_index = 0;  // The index of this counter.
 
   friend class DigitalGlitchFilter;
 };