Split RobotDrive class into a class for each drive type (#552)

DiffDrive.CurvatureDrive (aka CheesyDrive) and KilloughDrive were also added.
This reorganization paves the way for SwerveDrive.

wpilibc/src/main/native/include/Drive/DifferentialDrive.h

@@ -0,0 +1,99 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2008-2017 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <llvm/raw_ostream.h>
+
+#include "Drive/RobotDriveBase.h"
+
+namespace frc {
+
+class SpeedController;
+
+/**
+ * A class for driving differential drive/skid-steer drive platforms such as
+ * the Kit of Parts drive base, "tank drive", or West Coast Drive.
+ *
+ * These drive bases typically have drop-center / skid-steer with two or more
+ * wheels per side (e.g., 6WD or 8WD). This class takes a SpeedController per
+ * side. For four and six motor drivetrains, construct and pass in
+ * SpeedControllerGroup instances as follows.
+ *
+ * Four motor drivetrain:
+ * @code{.cpp}
+ * class Robot {
+ *  public:
+ *   frc::Talon m_frontLeft{1};
+ *   frc::Talon m_rearLeft{2};
+ *   frc::SpeedControllerGroup m_left{m_frontLeft, m_rearLeft};
+ *
+ *   frc::Talon m_frontRight{3};
+ *   frc::Talon m_rearRight{4};
+ *   frc::SpeedControllerGroup m_right{m_frontRight, m_rearRight};
+ *
+ *   frc::DifferentialDrive m_drive{m_left, m_right};
+ * };
+ * @endcode
+ *
+ * Six motor drivetrain:
+ * @code{.cpp}
+ * class Robot {
+ *  public:
+ *   frc::Talon m_frontLeft{1};
+ *   frc::Talon m_midLeft{2};
+ *   frc::Talon m_rearLeft{3};
+ *   frc::SpeedControllerGroup m_left{m_frontLeft, m_midLeft, m_rearLeft};
+ *
+ *   frc::Talon m_frontRight{4};
+ *   frc::Talon m_midRight{5};
+ *   frc::Talon m_rearRight{6};
+ *   frc::SpeedControllerGroup m_right{m_frontRight, m_midRight, m_rearRight};
+ *
+ *   frc::DifferentialDrive m_drive{m_left, m_right};
+ * };
+ * @endcode
+ *
+ * A differential drive robot has left and right wheels separated by an
+ * arbitrary width.
+ *
+ * Drive base diagram:
+ * <pre>
+ * |_______|
+ * | |   | |
+ *   |   |
+ * |_|___|_|
+ * |       |
+ * </pre>
+ *
+ * Each Drive() function provides different inverse kinematic relations for a
+ * differential drive robot. Motor outputs for the right side are negated, so
+ * motor direction inversion by the user is usually unnecessary.
+ */
+class DifferentialDrive : public RobotDriveBase {
+ public:
+  DifferentialDrive(SpeedController& leftMotor, SpeedController& rightMotor);
+  virtual ~DifferentialDrive() = default;
+
+  DifferentialDrive(const DifferentialDrive&) = delete;
+  DifferentialDrive& operator=(const DifferentialDrive&) = delete;
+
+  void ArcadeDrive(double y, double rotation, bool squaredInputs = true);
+  void CurvatureDrive(double y, double rotation, bool isQuickTurn);
+  void TankDrive(double left, double right, bool squaredInputs = true);
+
+  void StopMotor() override;
+  void GetDescription(llvm::raw_ostream& desc) const override;
+
+ private:
+  SpeedController& m_leftMotor;
+  SpeedController& m_rightMotor;
+
+  double m_quickStopAccumulator = 0.0;
+};
+
+}  // namespace frc