Cursor

[IanSeyler]

This pull request introduces enhancements to the linear framebuffer (LFB) driver and the PS/2 keyboard driver, focusing on improved cursor management and keyboard navigation support. The main changes include implementing a visual cursor in the LFB, adding keyboard arrow key detection, and improving code clarity and maintainability.

Linear Framebuffer (LFB) Cursor Management:

• Added a new visual cursor to the LFB display, including support for drawing, clearing, and updating its position (lfb_update_cursor). This includes new state variables (lfb_last_cursor, Cursor_Color, lfb_cursor_on) to manage cursor rendering. [1] [2] [3]
• Modified cursor movement routines (lfb_inc_cursor, lfb_dec_cursor) to call lfb_update_cursor after changing cursor position, ensuring the cursor display stays in sync.
• Updated the initialization routine to set the initial cursor position and state.

Keyboard Navigation Support:

• Added detection for arrow key scan codes in the PS/2 keyboard interrupt handler (ps2_keyboard_interrupt:), enabling support for left, right, up, and down arrow keys.
• Implemented handlers for arrow keys to set corresponding values in the key variable, allowing other parts of the system to respond to navigation input.

Other Improvements:

• Minor clarification in the serial driver initialization comment for accuracy.
• Removed a redundant call to lfb_clear in the LFB driver, streamlining the render routine.