Keyboard Driver

The keyboard driver handles input from a standard PS/2 keyboard.

1. Hardware Interface

• IRQ: 1 (Interrupt Vector 33).
• I/O Ports:
• 0x60: Data Port (Read scancodes).
• 0x64: Command/Status Port.

2. Scancodes & Mapping

TilekarOS supports PS/2 Scan Code Set 1.

• Make Code: Sent when a key is pressed (e.g., 0x1E for 'A').
• Break Code: Sent when a key is released (Make Code OR 0x80).
• Extended Scancodes: Start with 0xE0 (e.g., arrows, RALT, RCTRL).

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3. State Tracking

The driver tracks the state of modifier keys:

• Shift (Left/Right)
• Ctrl (Left/Right)
• Alt (Left/Right)
• CapsLock (Toggle)
• NumLock (Toggle)

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4. Key Events

The driver generates a KeyEvent structure for every key press or release:

typedef struct {
    enum KeyCode key_code;
    uint8_t scancode;
    bool pressed;
    bool shift_active;
    bool ctrl_active;
    bool alt_active;
    bool caps_lock;
    bool num_lock;
    char character;
} KeyEvent;

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5. Usage

Callback System

Register a custom callback function to handle keyboard events:

void my_keyboard_handler(KeyEvent event) {
    if (event.pressed && event.key_code == KEY_ESC) {
        // Handle ESC...
    }
}

keyboard_set_callback(&my_keyboard_handler);

Debug Mode (F1)

Pressing F1 toggles Kernel Debug Mode.

• When enabled, the kernel logs unknown scancodes and special key presses.
• It also enables/disables the VGA text cursor.