[sim] Move WPILib C++ sim implementations out of line (#2598)

This makes the sim classes consistent with the rest of the WPILibC classes.

wpilibc/src/main/native/cpp/simulation/JoystickSim.cpp

@@ -0,0 +1,63 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "frc/simulation/JoystickSim.h"
+
+#include "frc/Joystick.h"
+#include "frc/simulation/GenericHIDSim.h"
+
+using namespace frc;
+using namespace frc::sim;
+
+JoystickSim::JoystickSim(const Joystick& joystick)
+    : GenericHIDSim{joystick}, m_joystick{&joystick} {
+  // default to a reasonable joystick configuration
+  SetAxisCount(5);
+  SetButtonCount(12);
+  SetPOVCount(1);
+}
+
+JoystickSim::JoystickSim(int port) : GenericHIDSim{port} {
+  // default to a reasonable joystick configuration
+  SetAxisCount(5);
+  SetButtonCount(12);
+  SetPOVCount(1);
+}
+
+void JoystickSim::SetX(double value) {
+  SetRawAxis(
+      m_joystick ? m_joystick->GetXChannel() : Joystick::kDefaultXChannel,
+      value);
+}
+
+void JoystickSim::SetY(double value) {
+  SetRawAxis(
+      m_joystick ? m_joystick->GetYChannel() : Joystick::kDefaultYChannel,
+      value);
+}
+
+void JoystickSim::SetZ(double value) {
+  SetRawAxis(
+      m_joystick ? m_joystick->GetZChannel() : Joystick::kDefaultZChannel,
+      value);
+}
+
+void JoystickSim::SetTwist(double value) {
+  SetRawAxis(m_joystick ? m_joystick->GetTwistChannel()
+                        : Joystick::kDefaultTwistChannel,
+             value);
+}
+
+void JoystickSim::SetThrottle(double value) {
+  SetRawAxis(m_joystick ? m_joystick->GetThrottleChannel()
+                        : Joystick::kDefaultThrottleChannel,
+             value);
+}
+
+void JoystickSim::SetTrigger(bool state) { SetRawButton(1, state); }
+
+void JoystickSim::SetTop(bool state) { SetRawButton(2, state); }