4 files changed, 241 insertions, 0 deletions

diff --git a/src/input_common/CMakeLists.txt b/src/input_common/CMakeLists.txt
index 9f4422269..cfe5caaa3 100644
--- a/src/input_common/CMakeLists.txt
+++ b/src/input_common/CMakeLists.txt
@@ -10,8 +10,18 @@ set(HEADERS
             main.h
             )
 
+if(SDL2_FOUND)
+    set(SRCS ${SRCS} sdl/sdl.cpp)
+    set(HEADERS ${HEADERS} sdl/sdl.h)
+    include_directories(${SDL2_INCLUDE_DIR})
+endif()
+
 create_directory_groups(${SRCS} ${HEADERS})
 
 add_library(input_common STATIC ${SRCS} ${HEADERS})
 target_link_libraries(input_common common core)
 
+if(SDL2_FOUND)
+    target_link_libraries(input_common ${SDL2_LIBRARY})
+    set_property(TARGET input_common APPEND PROPERTY COMPILE_DEFINITIONS HAVE_SDL2)
+endif()
diff --git a/src/input_common/main.cpp b/src/input_common/main.cpp
index 8455fdc17..699f41e6b 100644
--- a/src/input_common/main.cpp
+++ b/src/input_common/main.cpp
@@ -7,6 +7,9 @@
 #include "input_common/analog_from_button.h"
 #include "input_common/keyboard.h"
 #include "input_common/main.h"
+#ifdef HAVE_SDL2
+#include "input_common/sdl/sdl.h"
+#endif
 
 namespace InputCommon {
 
@@ -17,12 +20,19 @@ void Init() {
     Input::RegisterFactory<Input::ButtonDevice>("keyboard", keyboard);
     Input::RegisterFactory<Input::AnalogDevice>("analog_from_button",
                                                 std::make_shared<InputCommon::AnalogFromButton>());
+#ifdef HAVE_SDL2
+    SDL::Init();
+#endif
 }
 
 void Shutdown() {
     Input::UnregisterFactory<Input::ButtonDevice>("keyboard");
     keyboard.reset();
     Input::UnregisterFactory<Input::AnalogDevice>("analog_from_button");
+
+#ifdef HAVE_SDL2
+    SDL::Shutdown();
+#endif
 }
 
 Keyboard* GetKeyboard() {
diff --git a/src/input_common/sdl/sdl.cpp b/src/input_common/sdl/sdl.cpp
new file mode 100644
index 000000000..ae0206909
--- /dev/null
+++ b/src/input_common/sdl/sdl.cpp
@@ -0,0 +1,202 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <cmath>
+#include <memory>
+#include <string>
+#include <tuple>
+#include <unordered_map>
+#include <SDL.h>
+#include "common/math_util.h"
+#include "input_common/sdl/sdl.h"
+
+namespace InputCommon {
+
+namespace SDL {
+
+class SDLJoystick;
+class SDLButtonFactory;
+class SDLAnalogFactory;
+static std::unordered_map<int, std::weak_ptr<SDLJoystick>> joystick_list;
+static std::shared_ptr<SDLButtonFactory> button_factory;
+static std::shared_ptr<SDLAnalogFactory> analog_factory;
+
+static bool initialized = false;
+
+class SDLJoystick {
+public:
+    explicit SDLJoystick(int joystick_index)
+        : joystick{SDL_JoystickOpen(joystick_index), SDL_JoystickClose} {
+        if (!joystick) {
+            LOG_ERROR(Input, "failed to open joystick %d", joystick_index);
+        }
+    }
+
+    bool GetButton(int button) const {
+        if (!joystick)
+            return {};
+        SDL_JoystickUpdate();
+        return SDL_JoystickGetButton(joystick.get(), button) == 1;
+    }
+
+    std::tuple<float, float> GetAnalog(int axis_x, int axis_y) const {
+        if (!joystick)
+            return {};
+        SDL_JoystickUpdate();
+        float x = SDL_JoystickGetAxis(joystick.get(), axis_x) / 32767.0f;
+        float y = SDL_JoystickGetAxis(joystick.get(), axis_y) / 32767.0f;
+        y = -y; // 3DS uses an y-axis inverse from SDL
+
+        // Make sure the coordinates are in the unit circle,
+        // otherwise normalize it.
+        float r = x * x + y * y;
+        if (r > 1.0f) {
+            r = std::sqrt(r);
+            x /= r;
+            y /= r;
+        }
+
+        return std::make_tuple(x, y);
+    }
+
+    bool GetHatDirection(int hat, Uint8 direction) const {
+        return (SDL_JoystickGetHat(joystick.get(), hat) & direction) != 0;
+    }
+
+private:
+    std::unique_ptr<SDL_Joystick, decltype(&SDL_JoystickClose)> joystick;
+};
+
+class SDLButton final : public Input::ButtonDevice {
+public:
+    explicit SDLButton(std::shared_ptr<SDLJoystick> joystick_, int button_)
+        : joystick(joystick_), button(button_) {}
+
+    bool GetStatus() const override {
+        return joystick->GetButton(button);
+    }
+
+private:
+    std::shared_ptr<SDLJoystick> joystick;
+    int button;
+};
+
+class SDLDirectionButton final : public Input::ButtonDevice {
+public:
+    explicit SDLDirectionButton(std::shared_ptr<SDLJoystick> joystick_, int hat_, Uint8 direction_)
+        : joystick(joystick_), hat(hat_), direction(direction_) {}
+
+    bool GetStatus() const override {
+        return joystick->GetHatDirection(hat, direction);
+    }
+
+private:
+    std::shared_ptr<SDLJoystick> joystick;
+    int hat;
+    Uint8 direction;
+};
+
+class SDLAnalog final : public Input::AnalogDevice {
+public:
+    SDLAnalog(std::shared_ptr<SDLJoystick> joystick_, int axis_x_, int axis_y_)
+        : joystick(joystick_), axis_x(axis_x_), axis_y(axis_y_) {}
+
+    std::tuple<float, float> GetStatus() const override {
+        return joystick->GetAnalog(axis_x, axis_y);
+    }
+
+private:
+    std::shared_ptr<SDLJoystick> joystick;
+    int axis_x;
+    int axis_y;
+};
+
+static std::shared_ptr<SDLJoystick> GetJoystick(int joystick_index) {
+    std::shared_ptr<SDLJoystick> joystick = joystick_list[joystick_index].lock();
+    if (!joystick) {
+        joystick = std::make_shared<SDLJoystick>(joystick_index);
+        joystick_list[joystick_index] = joystick;
+    }
+    return joystick;
+}
+
+/// A button device factory that creates button devices from SDL joystick
+class SDLButtonFactory final : public Input::Factory<Input::ButtonDevice> {
+public:
+    /**
+     * Creates a button device from a joystick button
+     * @param params contains parameters for creating the device:
+     *     - "joystick": the index of the joystick to bind
+     *     - "button"(optional): the index of the button to bind
+     *     - "hat"(optional): the index of the hat to bind as direction buttons
+     *     - "direction"(only used for hat): the direction name of the hat to bind. Can be "up",
+     *                                     "down", "left" or "right"
+     */
+    std::unique_ptr<Input::ButtonDevice> Create(const Common::ParamPackage& params) override {
+        const int joystick_index = params.Get("joystick", 0);
+
+        if (params.Has("hat")) {
+            const int hat = params.Get("hat", 0);
+            const std::string direction_name = params.Get("direction", "");
+            Uint8 direction;
+            if (direction_name == "up") {
+                direction = SDL_HAT_UP;
+            } else if (direction_name == "down") {
+                direction = SDL_HAT_DOWN;
+            } else if (direction_name == "left") {
+                direction = SDL_HAT_LEFT;
+            } else if (direction_name == "right") {
+                direction = SDL_HAT_RIGHT;
+            } else {
+                direction = 0;
+            }
+            return std::make_unique<SDLDirectionButton>(GetJoystick(joystick_index), hat,
+                                                        direction);
+        }
+
+        const int button = params.Get("button", 0);
+        return std::make_unique<SDLButton>(GetJoystick(joystick_index), button);
+    }
+};
+
+/// An analog device factory that creates analog devices from SDL joystick
+class SDLAnalogFactory final : public Input::Factory<Input::AnalogDevice> {
+public:
+    /**
+     * Creates analog device from joystick axes
+     * @param params contains parameters for creating the device:
+     *     - "joystick": the index of the joystick to bind
+     *     - "axis_x": the index of the axis to be bind as x-axis
+     *     - "axis_y": the index of the axis to be bind as y-axis
+     */
+    std::unique_ptr<Input::AnalogDevice> Create(const Common::ParamPackage& params) override {
+        const int joystick_index = params.Get("joystick", 0);
+        const int axis_x = params.Get("axis_x", 0);
+        const int axis_y = params.Get("axis_y", 1);
+        return std::make_unique<SDLAnalog>(GetJoystick(joystick_index), axis_x, axis_y);
+    }
+};
+
+void Init() {
+    if (SDL_Init(SDL_INIT_JOYSTICK) < 0) {
+        LOG_CRITICAL(Input, "SDL_Init(SDL_INIT_JOYSTICK) failed with: %s", SDL_GetError());
+    } else {
+        using namespace Input;
+        RegisterFactory<ButtonDevice>("sdl", std::make_shared<SDLButtonFactory>());
+        RegisterFactory<AnalogDevice>("sdl", std::make_shared<SDLAnalogFactory>());
+        initialized = true;
+    }
+}
+
+void Shutdown() {
+    if (initialized) {
+        using namespace Input;
+        UnregisterFactory<ButtonDevice>("sdl");
+        UnregisterFactory<AnalogDevice>("sdl");
+        SDL_QuitSubSystem(SDL_INIT_JOYSTICK);
+    }
+}
+
+} // namespace SDL
+} // namespace InputCommon
diff --git a/src/input_common/sdl/sdl.h b/src/input_common/sdl/sdl.h
new file mode 100644
index 000000000..3e72debcc
--- /dev/null
+++ b/src/input_common/sdl/sdl.h
@@ -0,0 +1,19 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "core/frontend/input.h"
+
+namespace InputCommon {
+namespace SDL {
+
+/// Initializes and registers SDL device factories
+void Init();
+
+/// Unresisters SDL device factories and shut them down.
+void Shutdown();
+
+} // namespace SDL
+} // namespace InputCommon