frontend/input_interpreter: Add InputInterpreter API

The InputInterpreter class interfaces with HID to retrieve button press states. Input is intended to be polled every 50ms so that a button is considered to be held down after 400ms has elapsed since the initial button press and subsequent repeated presses occur every 50ms.

Co-authored-by: Chloe <25727384+ogniK5377@users.noreply.github.com>

src/core/frontend/input_interpreter.h

@@ -0,0 +1,120 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+
+#include "common/common_types.h"
+
+namespace Core {
+class System;
+}
+
+namespace Service::HID {
+class Controller_NPad;
+}
+
+enum class HIDButton : u8 {
+    A,
+    B,
+    X,
+    Y,
+    LStick,
+    RStick,
+    L,
+    R,
+    ZL,
+    ZR,
+    Plus,
+    Minus,
+
+    DLeft,
+    DUp,
+    DRight,
+    DDown,
+
+    LStickLeft,
+    LStickUp,
+    LStickRight,
+    LStickDown,
+
+    RStickLeft,
+    RStickUp,
+    RStickRight,
+    RStickDown,
+
+    LeftSL,
+    LeftSR,
+
+    RightSL,
+    RightSR,
+};
+
+/**
+ * The InputInterpreter class interfaces with HID to retrieve button press states.
+ * Input is intended to be polled every 50ms so that a button is considered to be
+ * held down after 400ms has elapsed since the initial button press and subsequent
+ * repeated presses occur every 50ms.
+ */
+class InputInterpreter {
+public:
+    explicit InputInterpreter(Core::System& system);
+    virtual ~InputInterpreter();
+
+    /// Gets a button state from HID and inserts it into the array of button states.
+    void PollInput();
+
+    /**
+     * The specified button is considered to be pressed once
+     * if it is currently pressed and not pressed previously.
+     *
+     * @param button The button to check.
+     *
+     * @returns True when the button is pressed once.
+     */
+    [[nodiscard]] bool IsButtonPressedOnce(HIDButton button) const;
+
+    /**
+     * Checks whether any of the buttons in the parameter list is pressed once.
+     *
+     * @tparam HIDButton The buttons to check.
+     *
+     * @returns True when at least one of the buttons is pressed once.
+     */
+    template <HIDButton... T>
+    [[nodiscard]] bool IsAnyButtonPressedOnce() {
+        return (IsButtonPressedOnce(T) || ...);
+    }
+
+    /**
+     * The specified button is considered to be held down if it is pressed in all 9 button states.
+     *
+     * @param button The button to check.
+     *
+     * @returns True when the button is held down.
+     */
+    [[nodiscard]] bool IsButtonHeld(HIDButton button) const;
+
+    /**
+     * Checks whether any of the buttons in the parameter list is held down.
+     *
+     * @tparam HIDButton The buttons to check.
+     *
+     * @returns True when at least one of the buttons is held down.
+     */
+    template <HIDButton... T>
+    [[nodiscard]] bool IsAnyButtonHeld() {
+        return (IsButtonHeld(T) || ...);
+    }
+
+private:
+    Service::HID::Controller_NPad& npad;
+
+    /// Stores 9 consecutive button states polled from HID.
+    std::array<u32, 9> button_states{};
+
+    std::size_t previous_index{};
+    std::size_t current_index{};
+};