Mectov OS v34.0 — The Input Integrity & Compositor Correctness Update

The Mectov Kernel — an operating system kernel written from scratch in C and Assembly. No external libraries, no libc, no POSIX — every byte runs directly on hardware.

About

Mectov OS is a hobby operating system designed as a learning project and technical showcase. It boots via GRUB Multiboot, sets up protected mode with paging, and provides a fully graphical desktop environment with floating windows, custom static wallpapers, persistent draggable icons, hardware detection, standalone Ring 3 user applications, and real internet connectivity.

The v34.0 release is a correctness pass over the input path, the compositor, and the shell. Every item here is a subsystem that looked finished but was silently not doing its job:

1. Enforced Compositor Clipping: vga_set_clip() wrote four globals that no drawing primitive ever read, so the clip rectangle was a no-op and the Window Manager's content-area clip was never actually applied. Every primitive now intersects against it through shared clip_test() / clip_box() helpers, and vga_set_render_target() resets the clip so a stale rectangle cannot leak from one target into the next. Edge arithmetic moved to 64-bit so a caller-supplied width/height can no longer wrap an int.
2. Centralized Window Damage Tracking: Minimize and restore now live in wm_minimize() / wm_restore(), which own both halves of the operation — the state change and the dirty-region marking. This fixes minimizing from a taskbar button leaving the window painted on screen: that path duplicated the titlebar button's logic minus its mark_dirty() call.
3. Unified PS/2 Byte Arbitration: The 8042 controller has a single output buffer shared by the keyboard and the mouse. IRQ1, IRQ12, and speaker.c's delay loop each read port 0x60 without testing the AUX status bit, so they cannibalised each other's byte streams — the root cause of both stuck modifier keys and cursor teleporting. All three now route through one ps2_drain() that dispatches on status bit 5. Mouse packets with the X/Y overflow bits set are also no longer trusted for movement.
4. Eliminated Unkillable Shell Spins: int 0x80 is an interrupt gate, so IF=0 for the whole syscall and IRQ0 can never fire — every get_ticks() deadline reachable from the Ring 3 shell was therefore unreachable, wedging the machine with a task that could not even be killed. tunggu now uses the scheduler's sleep path, and the ping/DNS waits are bounded by net_wait_for(). timer_ticks is now correctly volatile.
5. VFS Read Buffer Overflow: vfs_read_file() wrote its NUL terminator one byte past the caller's buffer whenever a file exactly filled it — triggered on every boot through icons.cfg and on every .mct application launch.

Created by M Alif Fadlan.

---

Architecture

+--------------------------------------------------------------------+
|                       GRUB Multiboot (VBE)                         |
+--------------------------------------------------------------------+
|  boot.asm  -->  kernel.c  (kernel_main entry point)                |
+--------------------------------------------------------------------+
|  GDT (Ring 0+3)  |  IDT (ISR+IRQ)  |  TSS  |  Syscall (int 0x80)   |
+--------------------------------------------------------------------+
|  PIT Timer (1kHz) |  Keyboard (PS/2) |  Mouse (PS/2) |  Serial     |
+--------------------------------------------------------------------+
|  Memory Manager   |  VMM (Virtual Mem)|  IPC Message Queues        |
+--------------------------------------------------------------------+
|  Priority Thread   |  VFS + ATA PIO   |  PCI Scanner               |
+--------------------------------------------------------------------+
|  VGA/VESA Driver   |  Window Manager   |  RTL8139 NIC              |
+--------------------------------------------------------------------+
|  Network Stack (Ethernet/ARP/IPv4/ICMP/UDP/DNS)                    |
+--------------------------------------------------------------------+
|  MCT App Loader   |  Ring 3 User Tasks|  Display List Renderer     |
+--------------------------------------------------------------------+
|  Desktop (Squircle Icons) |  Taskbar (Glossy) |  Start Menu        |
+--------------------------------------------------------------------+
|  File Descriptors    |  UNIX Pipe           |  Login Screen         |
+--------------------------------------------------------------------+

Target Platform

• Architecture: i386 (32-bit x86), Monolithic Kernel
• Ring Levels: Ring 0 (Kernel) + Ring 3 (User Mode) — ACTIVE and Stable
• Scheduler: Preemptive Priority Round-Robin, Ring-Aware Context Switching
• Display: VESA VBE Linear Framebuffer, 1024x768, 32-bit color
• Storage: ATA PIO (IDE), 1MB virtual disk
• Audio: PC Speaker via PIT Channel 2
• Bus: PCI Configuration Space (ports 0xCF8/0xCFC)
• Network: RTL8139 NIC (virtual, via QEMU)
• Serial: COM1/COM2 UART 16550A (38400 baud, 8N1)

---

Core Subsystems

1. Modern Mouse Cursor (src/drivers/vga.c)

• High-Resolution Bitmap: Upgraded from 8x16 to a sleek 16x24 design.
• Premium Contrast: Black inner fill with a crisp white outline for maximum visibility on any background.
• Dynamic Drop Shadow: A real-time 50% alpha-blended shadow cast beneath the cursor for a depth effect.
• Zero Lag: Optimized drawing logic with dirty-region tracking.

2. Window Manager (src/gui/wm.c)

• Double-buffered rendering using fast memcpy with dirty region tracking.
• Z-ordered floating windows with proper overlap handling.
• Rounded corners (radius 8) on all windows for a modern look.
• Vibrant macOS-style "traffic light" control buttons with indicator symbols:
  • Close (vibrant red circle with 'X' symbol)
  • Minimize (vibrant yellow circle with '-' symbol)
  • Maximize (vibrant green circle with '+' symbol)
• Aero Snap: Drag windows to screen edges for automatic half-screen (left/right) or full-screen (top) snapping with saved geometry restore.
• Window Resizing: Drag any window edge or corner to resize. 8-directional edge detection with minimum size constraints (220×150).
• Window Close Callback: wm_close now notifies the terminal to kill child processes and reset state.
• Single-Owner Minimize/Restore: wm_minimize() and wm_restore() are the only supported ways to change a window's minimized state. They mark the damaged region dirty as part of the operation, because draw_one() skips minimized windows — nothing will ever repaint over the pixels a window leaves behind, so a caller that sets WmWin.minimized by hand produces a ghost. wm_focus_next() is the one deliberate exception: it rebuilds the z-order itself and covers the damage with a fullscreen mark.
• Clean Flat Aesthetic: Removed heavy shadows around windows to focus on a crisp, modern UI.

3. Taskbar & System Tray (src/gui/taskbar.c)

• WiFi Status Indicator: Replaced the RAM bar with a classic 3-arc WiFi icon, representing the OS's network capability.
• "Mectov OS" Start button with vertical separator line for distinct UI partitioning.
• Glossy dark background with Catppuccin Mocha accent border.
• Icon-only window buttons: each open app shown as a 16x16 squircle icon matching the desktop style. Clicking a button raises, minimizes, or restores its window through the Window Manager's wm_minimize() / wm_restore() API rather than reimplementing the state transition locally.
• System tray with:
  • CAPS indicator (vibrant red when active)
  • HDD activity LED (red flash on disk I/O)
  • Digital clock with day of week, adjusted for UTC+7 (WIB) timezone.

4. Real-time Rendering (kernel.c + src/drivers/vga.c)

• Shadow Framebuffer: Triple-buffer architecture (back_buffer → front_buffer_copy → VGA MMIO). Only pixels that actually changed are written to hardware, eliminating thousands of expensive KVM VM-Exits per frame.
• VSync Disabled: Removed VGA port 0x3DA polling which caused massive latency spikes under KVM virtualization.
• Forced 60Hz Loop: Constant 16ms redraw cycle with ultra-low render times (~4ms) thanks to delta-only copying.
• Microsecond Timing: Real-time FPS and render time measurement using PIT hardware counters.
• Enforced Clip Rectangle: vga_set_clip() / vga_reset_clip() define a rectangle in active render target coordinates that every primitive respects. put_pixel() gates on clip_test(), covering lines, circles, rounded-rect borders and all text rendering; draw_rect(), draw_rect_alpha() and draw_soft_shadow() gate on clip_box(), covering the filled and gradient primitives built on top of them. vga_blit_buffer() is deliberately exempt — it is a compositor operation that writes to back_buffer rather than to the render target, so it clips to the screen only.

5. Desktop Environment (src/gui/desktop.c)

• Custom Baked Wallpaper: Full-color 1024x768 image processed via Python build script.
• Professional Squircle Icons: High-end rounded-rect icons with minimalist glyphs and curated color palettes.
• Draggable Persistent Icons: Icon positions are saved to icons.cfg on the VFS and persist across system reboots.
• Application Double-Click Launcher: Desktop icons are fully interactive and support double-clicking to launch their respective .mct executable.

6. Login Screen (src/gui/login.c)

• Graphical login with wallpaper backdrop and semi-transparent overlay.
• Password input field with masked characters (●) and shake animation on wrong password.
• CAPS LOCK indicator warning.
• Sound feedback (beep) on login events.

7. Virtual Memory Manager (src/sys/vmm.c + src/include/vmm.h)

• Frame Bitmap Allocator: Tracks 128MB of physical memory (32768 pages) with a compact bitmap for O(1) allocation/free.
• Per-Process Address Spaces: vmm_create_page_dir() creates new page directories, vmm_clone_page_dir() copies kernel mappings for fork-like scenarios, vmm_free_page_dir() tears down an address space.
• Page Mapping: vmm_map_page() / vmm_map_pages() / vmm_unmap_page() with automatic TLB invalidation on CR3 reload.
• Region Allocator: vmm_find_free_region() locates free virtual address ranges starting at 0x08000000.
• Foundation for future demand paging and Copy-on-Write (COW) for Ring 3 process isolation.

8. IPC — Inter-Process Communication (src/sys/ipc.c + src/include/ipc.h)

• Named Message Queues: Fixed-size 64-byte messages with a 16-deep circular buffer per queue.
• Create & Connect: ipc_create_queue(name) for server processes, ipc_connect_queue(name) for clients.
• Blocking Receive: ipc_receive() blocks the calling task until a message arrives, with tick-based timeout support.
• Non-blocking Send: ipc_send() returns -1 immediately if the queue is full.
• Enables service-oriented architecture and clean multitasking app ecosystem.

9. Priority Thread Scheduler (src/sys/task.c + src/include/task.h)

• 4-Level Priority Round-Robin: IDLE(0) < LOW(1) < NORMAL(2) < HIGH(3). Higher priority runnable tasks always run first; round-robin scheduling within the same priority level.
• Thread API: task_create_thread() spawns a thread within the same process (shared address space) using a pid/tid model. task_exit_thread() terminates the current thread.
• Sleep/Wake: task_sleep(ticks) suspends a task for a specified duration; task_wake() resumes it. Used for efficient blocking I/O and timing.
• Process Lifecycle: task_kill(tid) for external termination (used by Ctrl+C). Zombie process detection in SYS_GET_EVENT auto-kills orphaned tasks.
• True CPU Yielding: SYS_YIELD now executes sti;hlt;cli to properly surrender the CPU until the next scheduler tick.
• Full context switching: general-purpose registers, EFLAGS, ESP, and per-task page_dir pointer for VMM integration.
• Per-task dual stacks: 16KB kernel stack + upgraded 64KB user stack to fully isolate memory under intensive network socket, file parsing, and DNS payload operations.
• IRQ0-driven scheduler tick (1000Hz) with cooperative yield.

10. Network Stack (src/drivers/net.c + src/drivers/rtl8139.c)

• RTL8139 NIC Driver: Full driver with PCI bus mastering.
• Ethernet/ARP/IPv4/ICMP/UDP/DNS: Complete local stack built directly into the kernel space.
• Reliable DNS Resolution: Upgraded DNS queries to point to QEMU's virtual gateway DNS server at 10.0.2.3 (switching from hardcoded 8.8.8.8) for robust internet routing.
• Background Net Poller: Embedded packet listening into the timer-based process scheduler to handle asynchronous inbound packets gracefully.
• Terminal commands: ping [ip] and host [domain].

11. Persistent File System (src/sys/vfs.c)

• Virtual File System (16 file slots) with auto-save to disk.img via ATA PIO.
• Persistence Fix: Reliable saving for configuration files like icons.cfg.
• Read Terminator Contract: vfs_read_file() returns the byte count and appends a NUL terminator only when the data left room for one. It never clamps the payload to max_size - 1 to make space, because load_mct_app_with_arg() passes max_size equal to the exact file size and needs every byte of it.

12. File Descriptor Layer (src/sys/fd.c + src/include/fd.h)

• UNIX-style FD abstraction: Per-task file descriptor table (16 FDs per task, 128 global) wrapping VFS nodes.
• Typed descriptors: FD_TYPE_FILE, FD_TYPE_PIPE_READ, FD_TYPE_PIPE_WRITE, FD_TYPE_DEV.
• Reference counting: Global FD entries with ref_count for safe sharing between threads.
• UNIX Pipe support: do_sys_pipe() creates a unidirectional pipe pair for inter-process data streaming.
• Full syscall integration: sys_open, sys_read, sys_write, sys_close, sys_pipe all route through the FD layer.

13. MCT Application Runtime (.mct)

• Custom Binary Format: 16-byte header with magic number verification and entry point specification.
• Fixed-Base Mapping: Applications are mapped at virtual address 0x02000000 within their own isolated page directory.
• Privilege Isolation: Clean transition from Ring 0 to Ring 3 via iret, ensuring user apps cannot execute privileged instructions.
• Launch Arguments: The kernel can pass arguments (like filenames) to newly launched Ring 3 tasks, retrievable via SYS_GET_LAUNCH_ARG.
• Independent Stacks: Each Ring 3 task maintains separate 16KB kernel and 64KB user stacks to avoid stack pointer overflows during large buffer parses.

14. User-Mode GUI API

• Direct Window Management: Ring 3 applications can now create, raise, and close their own GUI windows via syscalls.
• Graphics Primitive Syscalls: Accelerated SYS_DRAW_RECT and SYS_DRAW_TEXT for rendering directly into the application's window buffer.
• Event Polling & Persistence: SYS_GET_EVENT allows user apps to respond to window-specific mouse and keyboard input. It implements a two-phase close signal, giving apps a chance to safely save data to the VFS before terminating.
• Flicker-Free Updates: SYS_UPDATE_WINDOW ensures changes are committed to the display list and rendered during the next 60Hz frame sync.

15. Security & Pointer Validation (src/sys/syscall.c)

• Safe Syscall Entry: Every pointer passed from Ring 3 is validated via validate_user_ptr to prevent kernel memory corruption or unauthorized data access.
• Address Boundary Checks: Enforces strict memory boundaries (USER_MEM_LIMIT) for all syscall parameters.
• Zombie Cleanup: The kernel automatically detects and terminates Ring 3 processes whose GUI windows have been closed (if they refuse to exit voluntarily), preventing orphaned tasks and resource leaks.
• Privilege Separation: Use of Global Descriptor Table (GDT) and Task State Segment (TSS) to strictly enforce CPU privilege levels (Ring 0 vs Ring 3).

16. PS/2 IntelliMouse Scroll Wheel Support (src/drivers/mouse.c & src/gui/wm.c)

• Shared-Buffer Arbitration: The 8042 controller exposes one output buffer at port 0x60 for both the keyboard and the mouse, and status bit 5 is the only thing that says which device a byte came from. A single ps2_drain() (src/drivers/keyboard.c) owns the port: it loops while status bit 0 is set, dispatches each byte to keyboard_feed_byte() or mouse_feed_byte(), and is called by IRQ1, IRQ12, and speaker.c's delay loop alike — whichever gets there first delivers the byte to the right device instead of consuming it. The loop is capped at 64 iterations so an ISR can never spin unbounded on hardware.
• Packet Overflow Rejection: Bits 6/7 of packet byte 0 flag X/Y delta overflow. Those deltas are meaningless, so the driver keeps the button state and discards the movement rather than teleporting the cursor.
• Driver Upgrade: Upgraded PS/2 mouse driver to the 4-byte IntelliMouse protocol, using a custom rate-negotiation sequence (200 -> 100 -> 80) to detect scroll-capable hardware.
• Kernel Event Routing: The main kernel loop catches scroll deltas and dispatches them via wm_handle_scroll() to targeted windows, encoding up/down ticks as custom button events (0x10 and 0x20).
• Ring 3 Event Propagation: Emits standard event type 4 (Scroll Event) containing scroll direction delta (+1 for up, -1 for down) to Ring 3 apps via the SYS_GET_EVENT syscall.
• Full Application Integration: Native vertical scrolling integrated seamlessly across standard user-space applications:
  • Mini Browser: Scrolls active web page contents effortlessly (3 lines per tick).
  • File Explorer: Easy navigation through folder list structures.
  • PCI Manager: Smooth scrolling through the system hardware list.
  • Volume Manager: Intuitive scroll-to-adjust volume control (adjusts volume by ±5 per notch).

17. Sound Blaster 16 (SB16) Audio System (src/drivers/sb16.c)

• Sound Blaster Hardware Driver: Native ISA direct-register programming for Sound Blaster 16 compatibility.
• Dynamic WAV Playback: Supports loading and decoding dynamic 8-bit/16-bit mono/stereo .wav files via VFS and streaming audio through the virtual DSP.
• Sound Synthesis: Support for playing discrete frequencies (beeps) with programmable duration directly through Sound Blaster or PC Speaker hardware.
• Volume Controller Integration: Mapped to QEMU's PA sound engine (-device sb16,audiodev=snd0) for clear real-time system audio feedback.

18. Homegrown Dynamic Shared Library System (apps/lib/libc.c & libc.h)

• Dynamic Runtime Linking (libc.mct): Built a homegrown dynamic linking and loading subsystem. The dynamic loader (SYS_LOAD_LIBRARY / mct_load_library) retrieves the memory base of the export table for a library in memory.
• Extremely Slim Binaries: Ring 3 application executables (like browser.mct, explorer.mct, notepad.mct) no longer statically compile common functions, shrinking binary file sizes from 30KB+ to under 2KB.
• Standard Lib Wrappers: Full resolution of standard library functions at runtime via export table pointer indexes (__mct_lib_ptr):
  • String Handling: strlen, strcpy, strcat, atoi, itoa, itoa_pad
  • Formatting & Output: printf, sprintf
  • POSIX Wrappers: open, read, write, close, malloc, free, exit, sleep

19. Multi-Drive & Secondary ext2 Partition Support (src/sys/vfs.c & run.sh)

• ATA Dual Drive Support: Kernel ATA driver upgraded to detect and mount secondary IDE/ATA devices.
• Secondary ext2 Disk: Automatically creates and mounts a secondary 2MB virtual disk (ext2.img) initialized via mkfs.ext2 at index 1 in QEMU.
• Web Gateway Proxy Integration (gateway.py): Background gateway process running on the host that translates QEMU network queries and streams live data between the guest OS and the real internet.
• TCP Real-time Debugging Socket: Serial port debugging upgraded to a TCP socket server on port 45454 (replacing files-only logging), allowing real-time, zero-lag log streaming into our python interactive debugger (debug.py).

20. User-Space Terminal Emulator Enhancements (terminal.c)

• Interactive Shell Aliases & Shortcuts: Allows local registration of shortcuts (e.g. alias ll="ls -la", alias ..="cd ..") including wrapper aliases for complex MCT launches (e.g. alias browser="jalankan apps/browser.mct"). Type alias to print all active shortcuts.
• Modern Zsh-style Auto-suggestions: Searches command history backwards in real-time as the user types and renders suggestions inline in dim gray (0x08). Pressing Right Arrow or End at the end of the line instantly accepts the auto-suggested text.
• Advanced Inline Editing & Cursor Navigation: Fully supports non-ASCII key events for inline cursor movement via Left Arrow (0xE04B) and Right Arrow (0xE04D), instant jumping via Home (0xE047) and End (0xE04F), mid-string character insertion, and precise backspacing.
• Terminal Scrollback & Mouse Wheel: Expanded internal buffer from 24 rows to 128 rows (SCROLLBACK_ROWS). Incorporates mouse scroll wheel polling (Event Type 4) and Page Up/Page Down keyboard keys to scroll the terminal view smoothly, complete with a custom visual scrollbar indicator.
• Arrow-Key Command History & VFS Tab Completion: Tracks up to 16 commands in a circular buffer and dynamically queries the VFS to autocomplete both built-in shell commands and active directory files/folders.

21. Self-Hosted Gitea Integration (Git Hosting Migration)

• Home Server Remote Tracking: Added a dedicated gitea Git remote tracking the repository at https://git.mectov.my.id/maliffadlan/Mectov-OS.git.
• Infrastructure Autonomy: Seamlessly routes all future feature branch pushes, commit tracking, and code releases directly onto the self-hosted Gitea home server, operating as the primary remote alongside GitHub.

22. Copy-on-Write (COW) Virtual Paging (src/sys/vmm.c & src/sys/idt.c)

• Reference Counting Allocator: Added physical frame reference counting (frame_ref_count) to track shared pages across page directories.
• Fork-Style COW Address Spaces: Modified vmm_clone_address_space() to clone user space mappings without eager memory copy. Pages are marked read-only and flagged with PAGE_COW (bit 9).
• On-Demand Page Duplication: Page fault handler (Interrupt 14) intercepts writes to PAGE_COW pages, copying data dynamically when ref_count > 1, or directly promoting the page to writable if it's the sole remaining owner.

23. Environment Variables & Advanced Command Interpreter (src/sys/shell.c)

• Active Shell Context: Supports variable exports (e.g. export USER=bos_alif) and dynamic $VAR string interpolation for all script and terminal inputs.
• Interactive Aliasing: Built-in shell commands (alias, unalias, history) to manage custom command shortcuts, circular command history, and inline expansions.
• Robust Path Sanitization: Built-in sanitize_path to strip quotes, clean whitespace, and ensure resilient navigation (cd) and text display (cat, baca) even with spaces in pathnames (e.g. "notepad tes").
• Hang-Free Waiting: ex_cmd()'s live entry point is SYS_EXEC_CMD, and int 0x80 is an interrupt gate — so the whole command runs with IF=0 and the PIT cannot tick. Nothing in the shell may therefore block on the clock. tunggu calls task_sleep(), which re-enables interrupts and yields to the scheduler; the ARP/ping/DNS waits go through net_wait_for(), bounded by both a tick deadline and a hard spin cap so they return even when the tick source is frozen. Making the syscall path itself preemptible (a trap gate) remains the deeper fix and requires auditing every handler for re-entrancy first.

24. Process Control & Task Diagnostics (src/sys/task.c & src/sys/shell.c)

• Task Identification: Scheduler tracks process names dynamically via task_set_launch_arg() and task_get_launch_arg(), naming system services and desktop binaries accordingly.
• CLI Process Managers: ps command prints a beautiful colored table of PID, Ring, priority, status, and name; kill [PID] safely terminates user processes with PID range guard validation.
• Real-time Diagnostics: Added uptime command (reads PIT ticks and renders human-readable hours/minutes/seconds) and memstat command (queries physical RAM allocations and outputs dynamic heap allocator kmalloc_stats fragmentation data).

25. Per-Task Working Directories (src/sys/task.c & src/sys/vfs.c)

• Thread-Local Directories: Replaced the global current_dir VFS variable with a task-specific property (task_t.current_dir). Task directories are fully isolated; changing directories in one terminal does not disrupt other processes or desktop widgets.
• Boot Alignment: Suppressed VFS startup active directory restoration. The kernel always boots at / to align perfectly with the GUI Terminal initialization.
• Nano Absolute Path Resolution: Solved relative-path saving context bugs by immediately resolving files (e.g. nano note.txt in /home) to absolute paths in st_ed() before Window Manager callbacks process saving events.

26. VFS Integrity & Parallel Build System

• VFS Sector Growth Guard: Rebuilt the ATA VFS sector allocator to prevent contiguous file overwrite bugs. Files that grow past their original sector limits are dynamically moved to the end of the disk (next_data_sector), ensuring robust data safety.
• Build Isolation: Links independent .ld script targets named after target binaries to eliminate parallel linker race conditions during concurrent builds (make -j).

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Syscall API Reference

All syscalls are invoked via int 0x80. Register conventions: EAX=syscall number, EBX/ECX/EDX/ESI/EDI=arguments.

Core Syscalls (1–10)

#	Name	Description
1	SYS_PRINT	Print string. EBX=str_ptr, ECX=color
2	SYS_OPEN	Open/create VFS file. EBX=filename → return fd
3	SYS_READ	Read file. EBX=fd, ECX=buf, EDX=size → bytes read
4	SYS_WRITE	Write file. EBX=fd, ECX=buf, EDX=size → bytes written
5	SYS_CLOSE	Close file descriptor. EBX=fd
6	SYS_MALLOC	Allocate memory (Identity-mapped heap)
7	SYS_FREE	Free allocated memory
8	SYS_GET_TICKS	Get PIT timer tick count
9	SYS_YIELD	Yield CPU (sti;hlt;cli for true CPU surrender)
10	SYS_EXIT	Terminate current task

GUI Syscalls (11–17)

#	Name	Description
11	SYS_DRAW_RECT	Draw rectangle. EBX=win_id, ECX=x, EDX=y, ESI=(w<<16)|h, EDI=color
12	SYS_DRAW_TEXT	Draw text. EBX=win_id, ECX=x, EDX=y, ESI=str_ptr, EDI=color
13	SYS_GET_KEY	Get keyboard char (non-blocking) → char or 0
14	SYS_GET_MOUSE	Get mouse state → EAX=x, EBX=y, ECX=buttons
15	SYS_CREATE_WINDOW	Create window. EBX=x, ECX=y, EDX=w, ESI=h, EDI=title → win_id
16	SYS_GET_EVENT	Get window event. EBX=win_id, ECX=event_ptr (auto-kills zombie tasks)
17	SYS_UPDATE_WINDOW	Commit draw commands. EBX=win_id

Thread & Process Management (18–22)

#	Name	Description
18	SYS_THREAD_CREATE	Create thread. EBX=entry, ECX=priority, EDX=page_dir → TID
19	SYS_SLEEP	Sleep current task. EBX=ticks
20	SYS_GET_PID	Get current task ID / TID
21	SYS_SET_PRIORITY	Set task priority. EBX=tid, ECX=priority
22	SYS_GET_PRIORITY	Get task priority. EBX=tid → priority

IPC — Inter-Process Communication (23–28)

#	Name	Description
23	SYS_IPC_CREATE	Create message queue. EBX=key → queue ID
24	SYS_IPC_SEND	Send message (blocking). EBX=qid, ECX=type, EDX=data, ESI=len
25	SYS_IPC_RECV	Receive message (blocking). EBX=qid, ECX=type_out, EDX=data_out, ESI=len_out
26	SYS_IPC_DESTROY	Destroy queue. EBX=qid
27	SYS_IPC_TRY_SEND	Non-blocking send. Returns 0/-1
28	SYS_IPC_TRY_RECV	Non-blocking receive. Returns 0/-1

Virtual Memory (29–31)

#	Name	Description
29	SYS_VMM_MAP	Map page. EBX=vaddr, ECX=paddr, EDX=flags
30	SYS_VMM_ALLOC	Allocate virtual page. EBX=vaddr, ECX=flags → vaddr or 0
31	SYS_VMM_FREE	Free virtual page. EBX=vaddr

UNIX Compatibility & Hardware Interface (32–38)

#	Name	Description
32	SYS_PIPE	Create pipe pair. EBX=pipefd[2] → return 0/-1
33	SYS_GET_TIME	Get RTC clock time. EBX=rtc_time_t* ptr
34	SYS_PLAY_SOUND	Play PIT / Sound Blaster sound frequency. EBX=freq, ECX=duration_ms
35	SYS_GET_SYSINFO	Get hardware and kernel statistics. EBX=sysinfo_t* ptr
36	SYS_GET_PCI_INFO	Get list of detected PCI devices. EBX=pci_device_t* array, ECX=max
37	SYS_LIST_DIR	List VFS directory contents. EBX=dir_entry_t* array, ECX=max, EDX=parent_node
38	SYS_STAT_FILE	Get file attributes and node index. EBX=path_ptr

Network Stack (39–43)

#	Name	Description
39	SYS_DNS_RESOLVE	Asynchronously resolve domain to IP. EBX=domain_ptr
40	SYS_TCP_CONNECT	Open TCP socket connection. EBX=ip_ptr, ECX=port
41	SYS_TCP_SEND	Send raw TCP packet payload. EBX=data_ptr, ECX=len
42	SYS_TCP_RECV	Read TCP socket stream. EBX=buf_ptr, ECX=max_len → bytes read / state
43	SYS_NET_STATUS	Get packed network state (DNS resolved, TCP state)

Terminal & Extended Execution (44–51)

#	Name	Description
44	SYS_SET_STDOUT_IPC	Set process stdout redirection queue. EBX=qid (0 to disable)
45	SYS_EXEC_CMD	Run shell command program. EBX=cmd_string_ptr
46	SYS_GET_TASKS	Get list of running tasks. EBX=sys_task_info_t* array, ECX=max
47	SYS_GET_WINDOWS	Get list of open windows. EBX=sys_win_info_t* array, ECX=max
48	SYS_KILL_TASK	Force kill a task. EBX=tid
49	SYS_GET_LAUNCH_ARG	Get launch argument string. EBX=buf, ECX=max_len
50	SYS_CREATE_FILE	Directly create an empty file in VFS. EBX=filename
51	SYS_LOAD_LIBRARY	Dynamically load a shared library base. EBX=lib_name_ptr → base address

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Applications

Application	Type	Description
Terminal	Ring 3 (.mct)	Full terminal emulator with 16-command circular history (Up/Down arrows) and VFS tab autocomplete
Nano Editor	Ring 3 (.mct)	Windowed text editor for VFS files with stable auto-save
Notepad	Ring 3 (.mct)	Sleek text editor with menu bar options, Save As dialog, and dirty-state tracking
File Explorer	Ring 3 (.mct)	Browse and open stored files
System Info	Ring 3 (.mct)	Live RAM, CPU, resolution, uptime, and MAC address
Task Manager	Ring 3 (.mct)	Monitor CPU, RAM, and kill active user processes
PCI Manager	Ring 3 (.mct)	Scrollable table of detected PCI hardware with scroll wheel support
Music Player	Ring 3 (.mct)	Graphical audio player to stream and play mono/stereo dynamic .wav files via SB16
Volume Control	Ring 3 (.mct)	Slider utility to adjust system sound level, now supporting wheel scrolling
Clock	Ring 3 (.mct)	Digital clock with WIB timezone
Snake	Ring 3 (.mct)	Modern grid-based snake game in WM window with gradient body, score, speed scaling
Mini Browser	Ring 3 (.mct)	Text-mode web browser navigating via host proxy gateway with scroll support
Hello Ring 3	Ring 3 (.mct)	Demo user-space app with isolated memory and GUI window
GUI Calculator	Ring 3 (.mct)	Standalone external GUI calculator
Power Options	Ring 0	Shut Down, Restart, and Log Out dialog with accurate button hit-zones
DOOM Engine	Ring 0 (Port)	Full integration of the legendary 1993 DOOM engine with graceful exit to desktop

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Build and Run

Requirements

• gcc (with -m32 support)
• nasm
• make
• qemu-system-i386
• python3 + Pillow

Commands

# Clean and build the OS
make clean && make

# Run in QEMU
./run.sh

Building User Applications (.mct)

User mode applications are written in C, compiled with gcc -m32, and processed into the .mct format:

1. Compile: gcc -m32 -march=i386 -fno-pie -ffreestanding -c app.c -o app.o
2. Link: ld -m elf_i386 -T apps/app.ld app.o -o app.elf
3. Format: python3 build_mct.py app.elf app.mct
4. Deploy: The Makefile automatically handles this and uses inject_vfs.py to bake the .mct binaries into disk.img.

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Version History

Version	Highlights
v34.0	Input Integrity & Compositor Correctness Update: Made vga_set_clip() real — the clip rectangle was previously four globals that no drawing primitive ever read, so the WM's content-area clip silently did nothing; all primitives now gate on shared clip_test()/clip_box() helpers with 64-bit edge arithmetic, and vga_set_render_target() resets the clip between targets. Consolidated minimize/restore into wm_minimize()/wm_restore() so the state change and its dirty-region marking can no longer be separated, fixing windows minimized from the taskbar staying painted on screen. Unified all port 0x60 access behind a single ps2_drain() that dispatches on the 8042 AUX status bit, ending the keyboard/mouse byte theft behind stuck modifier keys and cursor teleporting, and added mouse packet overflow-bit rejection. Removed every unkillable spin from the shell: tunggu now uses task_sleep() and the ARP/ping/DNS waits use the doubly-bounded net_wait_for(), since int 0x80 is an interrupt gate and get_ticks() cannot advance during a syscall. Fixed vfs_read_file() writing its NUL terminator one byte past the caller's buffer on exact-fit reads. Marked timer_ticks volatile.
v33.1	Start Menu Ghosting Fix: Reordered full_redraw to call taskbar_pre_draw() before desktop_draw() so dirty rectangles are applied before the background is painted, ensuring closed popups are erased from the screen.
v33.0	Multi-Core (SMP) & APIC Update: Boot and initialize Application Processors via the INIT-SIPI-SIPI sequence with per-core GDT/TSS and IDT loading. Added Local APIC and I/O APIC drivers, disabling the legacy PIC and routing keyboard, mouse, and timer interrupts to the BSP. Parses the MADT for Interrupt Source Overrides to correctly route the PIT (IRQ0) to GSI 2 under QEMU. Resolved nested-interrupt scheduler deadlocks by removing spinlocks from schedule() and disabling interrupts before acquiring task_lock in task helpers. Also fixed Start Menu dismissal on outside clicks and desktop icon dragging.
v32.0	Syscall Modularization & VMM Memory Safety Update: Refactored monolithic syscall.c into modular handlers (syscall_gui.c, syscall_vfs.c, etc.). Fixed virtual memory heap overlap at 0x08000000 by placing heap_ptr after loaded app segments. Patched task_cleanup to switch CR3 back to kernel boot directory before freeing process address space. Bound-checked VFS node allocation in ext2.c to prevent fs_nodes[-1] array underflow.
v31.0	Graphics Pipeline & Compositing Performance Update: Shifted the main rendering loop in kernel.c to an event-driven model, removing forced 60Hz polling to lower idle CPU load to 0%. Optimized VRAM compositing in swap_buffers (src/drivers/vga.c) by comparing 2 pixels per iteration using 64-bit casting (uint64_t*), skipping static content instantly. Configured SYS_UPDATE_WINDOW syscall to trigger compositor redraws via global needs_redraw.
v30.2	Alt+Tab Window Switcher & English Localization Update: Added Left Alt modifier key press/release state tracking in the keyboard driver and intercepted Tab scancodes in the main loop to cycle focus between active windows via wm_focus_next(). Fixed Escape key (scancode 0x01) ASCII translation mapping. Translated all remaining Indonesian strings across menus, shell feedback, dialog boxes, and toolbar layouts to English.
v30.0	Clipboard, Explorer CRUD & Context Menu Update: Implemented global kernel clipboard manager (src/sys/clipboard.c) and user stubs for app copy-paste capability. Added "+File", "+Folder", and "Hapus" toolbar buttons with name input modals in File Explorer. Added kernel syscalls SYS_DELETE_FILE (58), SYS_MKDIR (59), and SYS_RENAME_FILE (60) to support Ring 3 CRUD actions. Implemented custom Catppuccin right-click context menus on Desktop and File Explorer for direct app launches, deletion, and renaming.
v29.0	File Association & Explorer Double-Click Update: Upgraded File Explorer (explorer.c) to support double-click (second-click on selected item) file associations. Double-clicking .mct runs the binary, .wav plays in Media Player (/apps/mplayer.mct), and other text files edit in Notepad (/apps/notepad.mct). Upgraded kernel command executor (src/sys/shell.c) to parse arguments for the jalankan command, splitting program path from arguments and launching via load_mct_app_with_arg().
v28.0	DOOM Memory Protection, HUD Font & Crash Recovery Update: Relocated kernel heap base from 16MB to 24MB (src/sys/mem.c) to completely resolve memory overlap/collision with the expanded kernel BSS section caused by DOOM's embedded static variables. Implemented integer precision formatting (%.3d) in doom_vsnprintf (doom/doom_libc.c) to fix HUD and quit-confirm pop-up font loading. Implemented automatic fullscreen flag reset (doom_fullscreen = 0) on task exit inside wm_cleanup_task (src/gui/wm.c) to prevent system-wide freezes on game exit/crash. Fixed overlapping desktop icons by aligning ICON_COUNT to 11 (src/include/desktop.h).
v27.8	Nano Path Resolution Update: Fixed relative path saving context bugs inside the kernel Nano editor (src/apps/nano.c) by resolving files to absolute paths via vfs_resolve_path() on startup. Upgraded the ed_fn buffer size from MAX_FILENAME (32) to MAX_PATH (256) in nano.c and apps.h to fully support deep path strings.
v27.7	Per-Task Working Directory Update: Refactored the VFS current_dir from a global system variable to a task-specific thread-local attribute (task_t.current_dir). This isolates working directories between terminals and GUI applications. Disabled active directory persistent restoration on boot to prevent prompt synchronization desync on startup.
v27.5	Absolute Path Launcher Update: Fixed a bug where changing the active directory in the Terminal (e.g. cd home) caused Desktop application icons and aliases to fail to open by rewriting all launchers and stubs to load apps using absolute paths (e.g., /apps/gcalc.mct instead of relative paths).
v27.4	System Diagnostics Update: Implemented native uptime and memstat commands in both the kernel shell and user-space Terminal. uptime displays human-readable runtime duration and total timer ticks, while memstat renders a complete breakdown of physical RAM allocation alongside heap allocator (kmalloc) metrics.
v27.3	VFS Path Sanitization Update: Implemented automatic quote-stripping and trailing-space trimming in all shell command path arguments, resolving file read and navigation failures for files with spaces (e.g., "notepad tes").
v27.2	Notepad GUI & Shortcut Update: Implemented Ctrl+S, Ctrl+N, and Ctrl+Q keyboard shortcuts for Notepad GUI in user mode. Redesigned the Save As interface into a centered modal dialog box. Fixed a bug where Notepad loaded its own binary (notepad.mct) on startup.
v27.1	Memory Overlap & Stability Fix: Fixed page directory/table corruption by adjusting KERNEL_RESERVED_PAGES to 64MB and capping max_heap at 32MB, ensuring 100% physical separation between heap and VMM frame pool.
v27.0	TCP Socket Redirection & Web Gateway Update: Implemented transparent HTTP port 80 redirection inside the kernel TCP stack (net_tcp_connect) routing to the host gateway at 10.0.2.2:8888. Enabled clean modern web browsing inside the Ring 3 Browser app (apps/browser.mct) using a Python gateway proxy (gateway.py) to parse real HTTPS web pages into memory-safe text.
v26.0	Copy-on-Write (COW) Paging & Integrated Editor Update: Added virtual page Reference Counting (frame_ref_count) and fully implemented Copy-on-Write (COW) address space cloning for Ring 3 process isolation. Fully integrated built-in GUI editor to edit, tulis, and new nano shell commands. Added sleek text editor status footer showing count and controls. Fixed persistent disk storage by removing the destructive disk.img deletion in run.sh.
v25.1	Advanced Shell Scripting, Environment Variables & Aliasing Update: Implemented automated script file execution (sh/source commands) with inline comment (#) parsing, whitespace trimming, and empty line skipping. Implemented Shell Environment Variables (export and $VAR expansion) in both terminal commands and scripts. Added command aliasing (alias, unalias, and a new history command) in the shell. Fixed nano editor to automatically create files if they don't already exist on save. Implemented kernel memmove, achieving a 100% warning-free build.
v25.0	IntelliMouse, Audio, Shell & Git Enhancements: Upgraded mouse driver to 4-byte IntelliMouse protocol supporting smooth scrolling in Browser, Explorer, PCI, and Volume Manager. Upgraded kernel audio to Sound Blaster 16 supporting dynamic WAV music stream playback. Built a dynamic shared library system (libc.mct) with a dynamic loading subsystem, reducing app binary sizes to ~1KB. Increased user stacks to 64KB and updated DNS to route over virtual gateway. Enhanced GUI Terminal with 16-command history buffer (Up/Down arrow navigation) and dynamic client-side VFS Tab completion. Gitea Migration: Added self-hosted home server remote gitea for private repository tracking.
v24.0	DOOM Engine Port: Fully playable port of the classic 1993 DOOM engine integrated directly into the kernel. Features keyboard polling, double buffer to MMIO front buffer translation, graceful OS exiting (vga_force_sync), and proper process teardown.
v23.0	Performance & Stability: Shadow Framebuffer (delta-only MMIO), VSync removal, zombie process detection + auto-kill, task_kill() API, Ctrl+C signal, Ctrl key tracking, Snake rewritten as WM app, terminal prompt protection, smart tab-completion with trailing space/slash, carriage return support, history display fix, power menu restart fix, -no-reboot removal.
v22.0	Kernel Modernization: Virtual Memory Manager (per-process address spaces, page mapping, region allocator), IPC named message queues (non-blocking send, blocking receive with timeout), 4-level priority thread scheduling with sleep/wake API, and 14 new syscalls (VMM/thread/IPC).
v21.0	Premium UI Refinement: High-res sleek mouse cursor with dynamic shadow, classic 3-arc WiFi indicator in system tray, and return to forced 60Hz real-time rendering loop.
v20.0	Modern UI Modernization: Professional squircle icons, vibrant macOS buttons with symbols (X, -, +), taskbar separator, flat design removal of shadows.
v19.0	Modern UI Redesign: Glass-morphism icons, Catppuccin theme, rounded corners, glossy taskbar.
v18.0	External App Ecosystem: .mct format, syscalls, Ring 3 apps (Calculator).
v17.0	Terminus Bold font, Draggable icons, VFS persistence.

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License

MIT License

Created by M Alif Fadlan.

Salah satu proyek OS hobi buatan Indonesia yang paling lengkap dan terdokumentasi dengan baik di GitHub saat ini