kernel: Add a blinking cursor to the terminal

kernel/src/arch/x86_64/CPU.cpp

@@ -161,7 +161,11 @@ void io_thread()
 static void timer_interrupt(Registers* regs, void*)
 {
     Timer::tick();
-    if (should_invoke_scheduler()) Scheduler::invoke(regs);
+    if (should_invoke_scheduler())
+    {
+        Scheduler::invoke(regs);
+        TextConsole::tick_cursor();
+    }
 }
 
 static void keyboard_interrupt(Registers*, void*)

kernel/src/fs/devices/ConsoleDevice.cpp

@@ -246,6 +246,9 @@ Result<u64> ConsoleDevice::ioctl(int request, void* arg)
     }
     case TTYSETGFX: {
         s_is_in_graphical_mode = (bool)arg;
+        if (!s_is_in_graphical_mode) TextConsole::enable_cursor();
+        else
+            TextConsole::disable_cursor();
         return 0;
     }
     default: return err(EINVAL);

kernel/src/video/TextConsole.cpp

@@ -47,6 +47,11 @@ static bool bold = false;
 static u32 g_x_position = 0;
 static u32 g_y_position = 0;
 
+static constexpr int CURSOR_TIMEOUT = 500;
+static int current_cursor_timeout = CURSOR_TIMEOUT;
+static bool cursor_activated = true;
+static bool cursor_enabled = true;
+
 static Utf8StateDecoder utf8_decoder;
 
 static Option<EscapeSequenceParser> escape_sequence_parser;
@@ -82,7 +87,7 @@ static void scroll()
 
 static bool should_scroll()
 {
-    return (g_y_position + FONT_HEIGHT) >= Framebuffer::height();
+    return g_y_position >= Framebuffer::height();
 }
 
 static void next_line()
@@ -106,6 +111,11 @@ static void erase_current_char()
     Framebuffer::rect(g_x_position, g_y_position, FONT_WIDTH, FONT_HEIGHT, BLACK);
 }
 
+static void draw_cursor()
+{
+    Framebuffer::rect(g_x_position, g_y_position, FONT_WIDTH, FONT_HEIGHT, WHITE);
+}
+
 static bool at_end_of_screen()
 {
     return (g_x_position + FONT_WIDTH) > Framebuffer::width();
@@ -323,6 +333,11 @@ namespace TextConsole
             if (handle_escape_sequence(c)) return;
         }
 
+        // Erase the current cursor.
+        if (cursor_enabled) erase_current_char();
+
+        bool should_draw_cursor = cursor_enabled;
+
         switch (c)
         {
         case L'\n': {
@@ -345,7 +360,10 @@ namespace TextConsole
         case L'\x1b':
         case L'\x9b':
         case L'\x90':
-        case L'\x9d': escape_sequence_parser = EscapeSequenceParser { (u8)c }; break;
+        case L'\x9d':
+            escape_sequence_parser = EscapeSequenceParser { (u8)c };
+            should_draw_cursor = false;
+            break;
         default: {
             if (_iscntrl(c)) return;
             putwchar_at(c, g_x_position, g_y_position);
@@ -358,6 +376,42 @@ namespace TextConsole
             break;
         }
         }
+
+        if (should_draw_cursor)
+        {
+            current_cursor_timeout = CURSOR_TIMEOUT;
+            cursor_activated = true;
+            draw_cursor();
+        }
+    }
+
+    void tick_cursor()
+    {
+        if (!cursor_enabled) return;
+
+        current_cursor_timeout--;
+        if (current_cursor_timeout == 0)
+        {
+            current_cursor_timeout = CURSOR_TIMEOUT;
+            cursor_activated = !cursor_activated;
+
+            if (cursor_activated) draw_cursor();
+            else
+                erase_current_char();
+        }
+    }
+
+    void disable_cursor()
+    {
+        cursor_enabled = false;
+    }
+
+    void enable_cursor()
+    {
+        cursor_enabled = true;
+        cursor_activated = true;
+        current_cursor_timeout = CURSOR_TIMEOUT;
+        draw_cursor();
     }
 
     Result<void> putchar(char c)

kernel/src/video/TextConsole.h

@@ -19,6 +19,9 @@ namespace TextConsole
     Result<void> println(const char* str);
     void wprintln(const wchar_t* str);
     Result<usize> printf(const char* format, ...) _format(1, 2);
+    void tick_cursor();
+    void disable_cursor();
+    void enable_cursor();
 
     u16 rows();
     u16 cols();