Skip to content

CHANGELOG.md

Latest commit

 

History

History
2435 lines (1821 loc) · 132 KB

CHANGELOG.md

File metadata and controls

2435 lines (1821 loc) · 132 KB
Raw

Mellivora OS - Changelog

v13.0.0 - Quality gates, benchmark observability, app manifests, new demos

Overview

This release promotes the project to v13 with a repository-wide consistency pass plus stronger release engineering. The main additions are version- and API-consistency validators, benchmark regression/trend tooling, a first pass at vNext desktop app-manifest infrastructure, and three new demo programs.

New Programs (programs/)

  • notify_demo.asm — Beginner service-API demo for SYS_NOTIFY and SYS_CLIPBOARD_COPY / SYS_CLIPBOARD_PASTE. Shows notification posting, clipboard round-trip, and simple interactive flow in text mode.

  • filepick.asm — Intermediate dialog-service demo for SYS_FILE_OPEN_DLG and SYS_FILE_SAVE_DLG. Opens a file chooser, reads the selected file, previews its first bytes in hex, and writes a saved copy.

  • netgraph.asm — Advanced live network latency visualizer. Repeatedly pings a target IP, records RTT samples, and renders a scrolling VGA text-mode bar graph of latency and timeouts.

Infrastructure

  • Added version-consistency validation so runtime strings, docs, OCI metadata, and bundled first-party manifest versions can be checked mechanically during make lint.

  • Added benchmark tooling in tests/bench.sh plus benchmark regression and trend analysis helpers. CI now publishes benchmark summaries and raw trend artifacts for review.

  • Added generated syscall contract artifacts (docs/syscalls.json and docs/syscalls.md) and lint checks that fail when generated API references drift from programs/syscalls.inc.

  • Added app manifest schema and example bundled-app manifests to establish the vNext launcher/permission metadata contract.

Other Changes

  • Boot/runtime version strings, documentation current-version references, and OCI package metadata have all been aligned to v13.0.0.

v12.4.0 - Conway's Life 3D, DFT analyser, JSON pretty-printer, C/ASM samples

Overview

Three new VBE and text-mode programs plus two new C samples completing the Phase 6 demo application batch.

New Programs (programs/)

  • life3d.asm — Conway's Game of Life on a 40×20 isometric diamond tilemap (640×480 VBE). Live cells rendered as raised shadow-glow tiles; dead cells as flat dark diamonds. Depth-sorted painter's-algorithm draw order. Wrapping toroidal boundary. Press ESC to quit.

  • fft.asm — 16-point DFT spectrum analyser (640×480 VBE bar chart). Implements direct-DFT O(N²) with integer fixed-point twiddle tables (scale=256). Three test signals selectable at runtime: cosine (energy at bins 2 and 14), square wave (odd harmonics), triangle wave (steeper roll-off). Bar height scaled to max magnitude; top-pixel highlight per bar. Keys 1/2/3 switch signal; ESC quits.

  • json.asm — Single-pass JSON pretty-printer (text mode). State machine parses compact JSON and re-emits it with 2-space indentation. Handles strings (including backslash escapes), numbers, booleans, null, nested objects and arrays. Accepts optional filename argument; falls back to a hardcoded demo object.

New Samples (samples/)

  • json_parse.c — Minimal JSON tokenizer in C. Tokenizes a hardcoded JSON string and prints each token's type name and value. Handles all structural tokens, strings with escape sequences, integers, floats, true/false/null. All-global-variable TCC convention; output via putchar(). Compile: tcc json_parse.c json_parse

  • echo_server.c — TCP echo server. Binds to port 8080, accepts one client at a time, echoes every received byte back, and closes the session on an empty line. Uses __asm__ volatile inline syscall wrappers for SYS_SOCKET/SYS_BIND/SYS_LISTEN/SYS_ACCEPT/SYS_RECV/SYS_SEND. Compile: tcc echo_server.c echo_server · Test: chat 127.0.0.1 8080

v12.3.0 - CHIP-8 emulator, SHA-256, matrix multiply, Mandelbrot C, HTTP Perl

Overview

New programs and samples: a complete CHIP-8 emulator (programs/chip8.asm), SHA-256 C implementation, 4×4 matrix multiplication, fixed-point Mandelbrot, and an HTTP/1.1 request-builder Perl demo. Boot banner updated to v12.2.0.

New Programs (programs/)

  • chip8.asm — Full CHIP-8 emulator (1977 Cosmac VIP ISA, all 35 opcodes). Loads .ch8 ROM files; falls back to built-in digits demo. Displays 64×32 at 8× scale (512×256) centred on a 640×480 VBE framebuffer. Full keypad mapping (1-4/Q-R/A-F/Z-V → keys 1-C/4-D/7-E/A-F). ESC to quit.

New Samples (samples/)

  • sha256.c — SHA-256 of the hardcoded string "Hello, Mellivora!". Pure C, no stdlib. Implements full message schedule expansion and all 64 compression rounds using global variables (TCC Mellivora convention). Compile: tcc sha256.c sha256

  • matrix_mul.c — 4×4 integer matrix multiplication (O(n³) standard algorithm). Prints matrices A, B, and C=A×B in a formatted grid. Compile: tcc matrix_mul.c matrix_mul

  • mandelbrot_fp.c — ASCII Mandelbrot set (70×22) using integer fixed-point arithmetic (scale=256, no floating point). Character palette maps iteration depth to density: " .:-=+*#@" (space is the first character). Compile: tcc mandelbrot_fp.c mandelbrot_fp

  • http_get.pl — HTTP/1.1 request builder and response parser demo in Perl. URL parsing (http://host:port/path), request header formatting, status-line / header parsing, and chunked transfer-encoding decoding. Run: perl http_get.pl

Other Changes

  • kernel/data.inc: boot banner and version_text updated from v12.1.0 to v12.2.0.

v12.2.0 - Phase 1 kernel fixes, pipe expansion, new samples

Overview

Kernel correctness patch: background-task exit codes are now propagated correctly, SIGCHLD is delivered to parent tasks on child exit, and the IPC pipe limit is raised from 8 to 32. Six new sample files are added across C, BASIC, and Perl.

SIGCHLD delivery on child exit (kernel/sched.inc, kernel/syscall.inc, kernel/data.inc)

Previously sched_exit_task marked the dying task as TASK_ZOMBIE and woke any sys_waitpid waiter, but never signalled the parent. Two bugs are fixed together:

  • Exit code was always 0: sched_exit_task stored mov dword [edi+TCB_EXIT_CODE], 0 unconditionally. The real code from EBX at sys_exit time was already clobbered by the page-freeing loop. Fix: sys_exit now saves EBX to bg_exit_code (new BSS dword in kernel/data.inc) before the first push, and sched_exit_task reads it back. sys_waitpid wake path also fills the waiter's EAX frame slot with the real exit code.

  • SIGCHLD never delivered: after the waitpid wake scan, sched_exit_task now reads TCB_PPID, scans the task table for the parent, and sets bit 17 (SIGCHLD) in TCB_SIG_PEND — unless the parent explicitly set SIG_IGN for SIGCHLD. If the parent is TASK_BLOCKED (in pause/sigsuspend, not waitpid), it is also woken.

Pipe count raised to 32 (kernel/ipc.inc)

IPC_MAX_PIPES raised from 8 to 32. All bounds checks already use the constant, so no other code changed. BSS grows by ~384 KB (32 × 16 400-byte pipe structs ≈ 512 KB total). Unblocks complex shell pipelines with many concurrent stages.

New samples

C (samples/)

  • sort.c — selection sort and bubble sort on a 16-element array; demonstrates sorting algorithms with the Mellivora TCC C environment.

BASIC (samples/)

  • mandelbrot.bas — ASCII Mandelbrot set using integer fixed-point arithmetic (scale factor 100); 60×22 character grid.
  • snake.bas — interactive snake game using LOCATE, INKEY$, DIM, SLEEP, and COLOR; adjustable-size board; score display.
  • blackjack.bas — blackjack card game with Fisher-Yates shuffle, ace reduction, and dealer hit-on-16 rules.

Perl (samples/)

  • csv.pl — CSV parser: parse, column-extract, filter by score, and sort by column.
  • regex_demo.pl — 14 regex examples: basic match, anchors, capture groups, named captures, substitution, trimming, grep/filter, split on regex.

v12.1.0 - Architectural correctness sprint: per-task fd isolation, blocking waitpid, W^X trampoline, errno, bug fixes

Overview

Corrects eleven architectural and correctness issues identified after the v12.0 POSIX sprint. No new user-visible syscalls except SYS_GETERRNO (181). Build remains a flat NASM binary.

Per-task file descriptor isolation (kernel/sched.inc, kernel/data.inc, kernel/isr.inc, kernel/syscall.inc)

Previously the global fd_table was shared by all 128 tasks, so concurrent tasks could corrupt each other's open file state. Each task now has a private 4 KB fd-table page.

  • TCB_FD_TABLE_PTR (offset 120) — pointer to task's private fd snapshot page.
  • sched_create_task: allocates and zero-fills a 4 KB PMM page, stores it in TCB_FD_TABLE_PTR.
  • sched_exit_task / sched_deliver_signals .sdel_default / sys_kill: all three task-termination paths now free the private fd page.
  • sched_swap_fd_tables — new helper called at every context switch point (irq_timer, sys_yield, sys_sleep, sys_pause, sys_sigsuspend, sys_waitpid): saves the global fd_table into the outgoing task's private page (or shell_fd_table when returning to the shell), then loads the incoming task's private page (or shell_fd_table) into fd_table.
  • shell_fd_table (kernel/data.inc): new 256-byte BSS array holds the shell's own fd snapshot so the shell's state persists across task switches.

TCB_SIZE grows from 116 to 128 bytes

Three new fields appended to the TCB:

Field Offset Description
TCB_WAIT_PID 116 PID being waited on in sys_waitpid (0 = not waiting)
TCB_FD_TABLE_PTR 120 Physical address of private fd-table page
TCB_ERRNO 124 Per-task errno value

Blocking sys_waitpid (kernel/sched.inc)

The previous implementation spun up to 2 000 times calling int 0x80 / SYS_YIELD from ring-0, which is a no-op on this kernel (PIT only preempts ring-3 code). Ring-3 callers would effectively hang the system.

  • Ring-3 callers are now truly blocked: TCB_STATE = TASK_BLOCKED, TCB_WAIT_PID set to the target PID (or -1 for any child), ESP saved in TCB_ESP, and the scheduler immediately switches to the next READY task. If no task is ready, execution returns to the shell (which runs ring-0 and is never preempted).
  • sched_exit_task scans for any TASK_BLOCKED task whose TCB_WAIT_PID matches the dying child's PID, writes the exit code into its saved [TCB_ESP+28] (EAX slot), sets the task TASK_READY, and clears TCB_WAIT_PID. The woken task resumes from its iretd with the correct exit code in EAX.
  • Shell (ring-0) callers fall through immediately with -1 if the child is not already a zombie (non-blocking single scan only).

Read-only signal trampoline / W^X fix (kernel/paging.inc, kernel/sched.inc)

The sigreturn stub (MOV EAX,144; INT 0x80; NOP) was previously written directly to the user stack on every signal delivery, making the user stack both writable and executable (W^X violation). The stack is no longer executable in systems that enforce it.

  • sigreturn_trampoline_init (kernel/paging.inc): allocates one physical page, writes the 8-byte stub, then maps it read-only (PG_PRESENT | PG_USER, no PG_WRITABLE) at SIGRETURN_TRAMPOLINE_VADDR = 0x1FFFF000 (last page of the 128–512 MB demand zone). Called from paging_init after paging is enabled.
  • sched_deliver_signals now sets [new_esp + 0] = SIGRETURN_TRAMPOLINE_VADDR instead of a stack-local return address, and zeros the previously-used stub bytes [new_esp+24..31].

sys_geterrno — per-task errno (kernel/syscall.inc, kernel.asm)

  • New syscall 181 SYS_GETERRNO: returns TCB_ERRNO for the running task (0 from shell).
  • Errno constants added to kernel.asm: ENOENT=2, EBADF=9, ENOMEM=12, EACCES=13, EFAULT=14, EINVAL=22, EMFILE=24, ENOTTY=25, ENOSYS=38.

sys_fcntl fd validation fix (kernel/syscall.inc)

  • Added cmp ebx, FD_MAX; jge .fcntl_badf bounds check at entry.
  • F_GETFL and F_SETFL now check FD_FLAG_CLOSED and return -1 for closed fds.

sys_ioctl security and correctness fix (kernel/syscall.inc)

  • TIOCGWINSZ: calls validate_user_ptr(EDX) before writing winsize struct. A null or out-of-range pointer now returns -1 instead of faulting or corrupting kernel memory.
  • Unknown ioctl requests now return -1 (was 0, masking errors from callers).

sys_mmap / sys_munmap register fixes (kernel/syscall.inc)

  • sys_mmap: aligned byte length is now right-shifted by 12 (shr eax, 12) before passing to pmm_alloc_pages, which expects a page count, not a byte count.
  • sys_munmap: EAX = EBX (address) and ECX = page count are now set correctly before calling pmm_free_pages. Previous code had a no-op mov ebx, ebx and left EAX/ECX undefined.

sys_ftruncate block deallocation (kernel/syscall.inc)

When the new size is smaller than the current size, excess HBFS blocks are now freed:

if new_block_count < old_block_count:
    hbfs_free_blocks(start_block + new_count, old_count - new_count)
    fd_entry[block_count] = new_block_count
fd_entry[size] = new_size

sys_recvfrom from-address fill (kernel/syscall.inc)

Previously a stub (jmp sys_recv) that silently dropped the from* argument. Now a full implementation: performs the same receive logic as sys_recv, then—if EDI (the from* pointer) is non-null and passes validate_user_ptr—fills a sockaddr_in with AF_INET, SOCK_REMOTE_PORT, and SOCK_REMOTE_IP from the socket struct.

v12.0.0 - POSIX compliance sprint: 36 new syscalls (145–180), TCB extension

Overview

This release makes a major step toward POSIX compliance by adding 36 new system calls covering FD operations, session management, signal extensions, environment queries, identity management, networking extensions, and terminal (termios) control.

TCB extension (kernel/sched.inc)

TCB_SIZE grows from 88 to 116 bytes. Seven new fields:

Field Offset Description
TCB_EUID 88 Effective UID
TCB_EGID 92 Effective GID
TCB_SID 96 Session ID
TCB_UMASK 100 File creation mask
TCB_ITIMER_VAL 104 Interval timer current value (ticks)
TCB_ITIMER_INT 108 Interval timer interval (ticks)
TCB_SAVED_MASK 112 Saved signal mask (for sigsuspend)

sched_create_task initialises: EUID=UID, EGID=GID, SID=own PID, UMASK=022, itimer fields=0. sys_fork child inherits EUID/EGID and clears itimer and saved mask.

Scheduler fixes (kernel/sched.inc, kernel/isr.inc)

  • sched_wake_sleepers: added guard TCB_WAKEUP==0 → skip so tasks blocked indefinitely (via pause/sigsuspend) are not prematurely woken by the clock.
  • sys_signal wake path: when a non-SIGKILL/non-term signal is delivered to a TASK_BLOCKED task (e.g. sleeping in pause), the task is set TASK_READY so it gets scheduled and sched_deliver_signals fires.
  • sched_check_itimers: new function, called from irq_timer after sched_check_alarms, decrements TCB_ITIMER_VAL for each non-free task; when it reaches 0, sets SIGALRM pending, wakes blocked tasks, and reloads from TCB_ITIMER_INT (0 = one-shot, disarm).

New syscalls (kernel/syscall.inc, programs/syscalls.inc)

FD operations (145–151)

# Name Description
145 SYS_FSTAT stat an open fd → fills 12-byte stat_buf
146 SYS_FTRUNCATE truncate file by fd to new size (in-memory)
147 SYS_FCHMOD change mode by fd (stub, accepted)
148 SYS_FCHOWN change owner by fd (stub, accepted)
149 SYS_FSYNC flush fd to storage (write-through, no-op)
150 SYS_LINK hard-link: creates new dirent sharing same blocks
151 SYS_ISATTY returns 1 for fd 0–2 (stdin/stdout/stderr)

Session management (152–156)

# Name Description
152 SYS_SETSID create new session (fails if already group leader)
153 SYS_GETSID get session ID by PID (0 = self)
154 SYS_WAIT reap any zombie child (WNOHANG semantics)
155 SYS_PAUSE block until any signal arrives (returns −1/EINTR)
156 SYS_UMASK set/query file creation mask; pass 0xFFFFFFFF to query

Signal extensions (157–160)

# Name Description
157 SYS_SIGPENDING write pending unblocked signals to caller's sigset
158 SYS_SIGSUSPEND atomically set mask, block until signal; restores old mask
159 SYS_SETITIMER set/query ITIMER_REAL interval timer (usec precision, 100 Hz)
160 SYS_GETITIMER query ITIMER_REAL current value

Environment / system info (161–165)

# Name Description
161 SYS_SETENV set/add environment variable with optional overwrite
162 SYS_UNSETENV remove environment variable
163 SYS_UNAME fill utsname: Mellivora / 12.0.0 / i386
164 SYS_UTIME update file mtime (utimbuf or current timestamp)
165 SYS_SYSCONF query _SC_* constants: ARG_MAX, CLK_TCK, OPEN_MAX, etc.

Identity (166–169)

# Name Description
166 SYS_SETEUID set effective UID (root or matching real UID allowed)
167 SYS_SETEGID set effective GID
168 SYS_SETREUID set real+effective UID (−1 = keep current)
169 SYS_SETREGID set real+effective GID

Networking extensions (170–176)

# Name Description
170 SYS_SENDTO send with optional UDP destination; delegates to sys_send
171 SYS_RECVFROM receive; delegates to sys_recv
172 SYS_SETSOCKOPT set socket option (SO_REUSEADDR stored, rest accepted)
173 SYS_GETSOCKOPT get SO_TYPE (SOCK_STREAM/SOCK_DGRAM)
174 SYS_GETSOCKNAME return local sockaddr_in (local port, 0.0.0.0)
175 SYS_GETPEERNAME return remote sockaddr_in
176 SYS_SHUTDOWN close one or both socket halves (SHUT_RD/WR/RDWR)

Terminal control (177–180)

# Name Description
177 SYS_TCGETATTR return cooked-mode termios for fd 0–2
178 SYS_TCSETATTR store termios in tty_termios shadow (fd 0–2)
179 SYS_TCDRAIN no-op (write-through I/O)
180 SYS_TCFLUSH no-op

New constants (programs/syscalls.inc)

SYS_FSTAT=145 … SYS_TCFLUSH=180, plus: _SC_ARG_MAX, _SC_CLK_TCK, _SC_OPEN_MAX, _SC_PAGESIZE, ITIMER_REAL, SHUT_RD/WR/RDWR, AF_INET, termios flag constants.

Data (kernel/data.inc)

  • tty_termios: 36-byte BSS buffer for tcsetattr/tcgetattr shadow.

v11.0.0 - User-space signal delivery, AHCI/e1000 drivers, GDB stub, 144 syscalls

User-space signal handlers

  • TCB_SIG_HAND (kernel/sched.inc) — new TCB field (offset 84) holds a pointer to a lazily-allocated 4 KB PMM page used as a 32-dword handler table (one slot per signal). TCB_SIZE grows from 84 to 88 bytes. Child tasks start with TCB_SIG_HAND = 0 (table not yet allocated); sys_fork clears the field so children inherit only default actions, not handler function pointers.

  • SIG_DFL / SIG_IGN — new constants (sched.inc / syscalls.inc). SIG_DFL = 0 means restore the kernel default action; SIG_IGN = 1 silently discards the signal.

  • sched_deliver_signals (kernel/sched.inc) — called by irq_timer every context switch with EBX = TCB pointer and EDI = iretd frame base address. For each pending, unmasked signal it builds a 28-byte signal frame on the user stack:

    [new_esp +  0]  return address  → points to inline sigreturn stub
[new_esp +  4]  signum          (cdecl argument)
[new_esp +  8]  saved EIP       (interrupted ring-3 EIP)
[new_esp + 12]  saved EFLAGS
[new_esp + 16]  saved ESP       (original user stack pointer)
[new_esp + 20]  stub: MOV EAX,144 / INT 0x80 / NOP (8 bytes)

    The iretd frame EIP3 is redirected to the user handler and ESP3 is set to new_esp. When the handler returns it lands on the stub which transparently invokes sys_sigreturn. Default actions: SIGKILL/SIGTERM/SIGINT → terminate task; SIGTSTP → pause; SIGCONT → no-op; all others → terminate.

  • irq_timer (kernel/isr.inc) — updated to call sched_deliver_signals on both the "stay on current task" and "switch to new task" paths before performing iretd.

New syscalls

  • SYS_SIGACTION (143) — install or query a signal handler. EBX = signum, ECX = handler (fn ptr / SIG_DFL / SIG_IGN), EDX = ptr to receive old handler (or 0). Validates signum, rejects SIGKILL. Allocates the 4 KB handler table on first use (zero-filled = all SIG_DFL). Returns 0 on success, -1 on error.
  • SYS_SIGRETURN (144) — return from a signal handler. Called automatically by the inline stub on the user stack. Restores the saved EIP, EFLAGS, and ESP from the signal frame, discarding the signal stack entirely. No user arguments needed.

Kernel drivers (carried from previous development sprint)

  • AHCI SATA driver (kernel/ahci.inc) — full AHCI HBA detection via PCI scan; maps one AHCI port (first populated port found), initialises command-list / FIS / command-table in PMM-allocated memory, and exposes ahci_read_sectors, ahci_write_sectors, and ahci_flush. ahci_present flag lets VFS/HBFS fall back to legacy ATA when no AHCI controller is available.
  • Intel e1000 NIC driver (kernel/e1000.inc) — probes PCI for common Intel GbE device IDs (82540EM, 82545EM, 82543GC, 82544GC); reads MAC from RAL0/RAH0; initialises 8 TX and 8 RX descriptors with 2048-byte buffers; hooks into the existing net_send_frame dispatcher (NIC_TYPE_E1000 = 2).
  • GDB remote stub (kernel/gdbstub.inc) — hooks INT 1 (single-step) and INT 3 (breakpoint) via idt_set_gate; implements the GDB RSP packet protocol over COM1 (blocking I/O); supports ?, g, G, p, P, m, M, c, s, Z0, z0, and k commands; 32 software breakpoint slots; 1024-byte packet buffer.

New programs

  • trap — demo that installs a SIGUSR1 handler via SYS_SIGACTION, prints its PID, sleeps in a loop, and prints a message each time the signal is delivered. Exits after three received signals. Useful for testing the signal delivery path end-to-end.

API changes

  • programs/syscalls.inc — new constants SYS_SIGACTION = 143, SYS_SIGRETURN = 144, SIG_DFL = 0, SIG_IGN = 1.
  • Syscall table now has 144 defined entries (was 142).

v10.0.0 - UEFI boot, VFS layer, HBFS v3, compositor IPC, 140 syscalls, package manager

Boot & architecture

  • UEFI bootloader (boot/uefi_loader.c) — PE32+ EFI application built with gnu-efi; detects UEFI vs BIOS at boot time, sets up GOP framebuffer, memory map, and hands off to the kernel via a BOOT_INFO struct. make uefi produces boot/uefi_loader.efi; make run-uefi launches QEMU with OVMF firmware and a GPT/FAT ESP image.
  • x86-64 long-mode path (stage2.asm) — Stage 2 now optionally transitions to 64-bit long mode when compiled with -DKERNEL_64BIT=1 (make 64bit). PAE paging, GDT64, and a minimal long-mode entry stub are conditionally assembled; the 32-bit protected-mode path is unchanged.
  • BOOTINFO_UEFI_MAGIC / UEFI_BOOT_MAGIC — kernel detects UEFI vs BIOS at runtime by inspecting the boot-info magic passed from Stage 2.

Virtual filesystem (kernel/vfs.inc)

  • VFS abstraction layer — unified vfs_open / vfs_read / vfs_write / vfs_readdir / vfs_stat / vfs_mkdir / vfs_unlink front-ends dispatch to pluggable backend drivers via a mount table (up to 8 mounts, VFS_MAX_MOUNTS).
  • Four built-in backends — HBFS (/), procfs (/proc), devfs (/dev), tmpfs (/tmp).
  • procfs — /proc/uptime, /proc/meminfo, /proc/version, /proc/cpuinfo, and /proc/<pid>/status (reports task name from TCB).
  • devfs — /dev/null, /dev/zero, /dev/random (LCG), /dev/tty (serial loopback).
  • tmpfs — in-memory files backed by PMM pages; up to TMPFS_MAX_FILES entries.
  • /dev/full — new devfs node (DEV_FULL); reads return zero bytes (like /dev/zero), writes always return -1 (ENOSPC simulation); enumerated by vfs_dev_readdir.
  • 64 virtual file descriptors (VFS_MAX_FDS, VFD_SIZE = 32) per system (expanded from per-process FD_MAX = 8 for legacy syscalls).
  • VFS-aware shell navigation — cmd_cd_internal (.cd_enter_subdir) now recognises /proc, /dev, and /tmp as valid virtual-directory targets at root level; sets current_dir_lba = 0xFFFFFFFF (sentinel) so build_cwd_path produces e.g. /proc which vfs_route correctly dispatches to procfs. Guard at the top of .cd_enter_subdir prevents HBFS ATA reads when the CWD is a virtual directory.
  • VFS-aware ls — cmd_list_dir detects the 0xFFFFFFFF sentinel LBA and, instead of calling hbfs_load_root_dir, iterates vfs_readdir in a loop to list entries from the active VFS backend (procfs, devfs, or tmpfs).

HBFS v3 (kernel/hbfs.inc, kernel.asm)

  • File permissions (HBFS_DE_MODE) — Unix-style 12-bit mode field in every directory entry; hbfs_check_permission(EBX=dirent, ECX=requested) enforces owner/group/other rwx bits.
  • Extended attributes (HBFS_DE_XATTR_LBA, HBFS_DE_XATTR_COUNT) — each file can have an xattr block holding up to HBFS_XATTR_PER_BLOCK key/value pairs; hbfs_xattr_get and hbfs_xattr_set are the kernel API; SYS_GETXATTR (141) / SYS_SETXATTR (142) expose them to user-space programs. sys_setxattr upgrades the on-disk filesystem from v2 to v3 and sets HBFS_FEAT_XATTR in the superblock on first use. sys_getxattr checks the feature flag and returns -1 on a filesystem that has never written any xattrs.
  • Feature flags (HBFS_SB_FEATURES) — HBFS_FEAT_JOURNAL (existing), HBFS_FEAT_XATTR, HBFS_FEAT_PERM; superblock validated on mount.
  • Dirent layout v3 — new constants HBFS_DE_NAME=0, HBFS_DE_TYPE=253, HBFS_DE_SIZE=256, HBFS_DE_BLOCK=260, HBFS_DE_MTIME=272, HBFS_DE_MODE=276, HBFS_DE_XATTR_LBA=280, HBFS_DE_XATTR_COUNT=284; entry size raised to HBFS_DIR_ENTRY_SIZE = 288.
  • hbfs_xattr_set key-update fix — the scan loop now performs a real repe cmpsb key comparison against each occupied slot; on a match the value field is updated in-place instead of creating a duplicate entry (previously the comparison was a no-op stub). Stack-offset bugs in the new-slot write path (wrong frame offsets for key_ptr and val_ptr after two intermediate pushes) are also corrected; key and value pointers are now saved to static locals (hxs_key_ptr, hxs_val_ptr) immediately after pushad to avoid frame-offset arithmetic errors.
  • sys_defrag Phase 2 — block relocation (SYS_DEFRAG = 104) — replaces the v9 stub that only counted fragmentation. For each non-free, non-directory directory entry the defragmenter scans the bitmap for the lowest free contiguous run entirely before the file's current start block; if found it copies all file sectors using hbfs_block_buf as a 512-byte staging buffer, updates the bitmap (destination bits set before source bits cleared to prevent double-use), and writes the new start block back to the directory entry. Phase 1 fragmentation counting is retained; EAX returns the frag-run count measured before relocation. Bitmap and root directory are flushed to disk, and the superblock is journalled on HBFS v2+ volumes.
  • Journal version check fix — all journal entry points (hbfs_journal_begin, hbfs_journal_log_sector, hbfs_journal_commit, and sys_defrag) previously accepted only HBFS_VERSION_V2 exactly. Comparisons changed to jb HBFS_VERSION_V2 so that v3 filesystems receive identical journal protection; v1 volumes continue to skip the journal. hbfs_init likewise uses jb so v3 mounts trigger journal-recovery scanning on unclean shutdown.

Syscall interface (kernel/syscall.inc, programs/syscalls.inc)

  • 142 syscalls — table extended to 256 entries; new POSIX-compat range 116–142:
    • SYS_DUP (116), SYS_DUP2 (117), SYS_FCNTL (118), SYS_IOCTL (119), SYS_MMAP (120), SYS_MUNMAP (121), SYS_MPROTECT (122), SYS_SELECT (123), SYS_CLOCK_GETTIME (124), SYS_NANOSLEEP (125), SYS_GETTIMEOFDAY (126), SYS_GETUID (127), SYS_SETUID (128), SYS_GETGID (129), SYS_SETGID (130), SYS_GETEUID (131), SYS_GETEGID (132), SYS_ACCESS (133), SYS_PIPE2 (134), SYS_SURFACE_CREATE (135), SYS_SURFACE_COMMIT (136), SYS_SURFACE_DESTROY (137), SYS_SURFACE_MOVE (138), SYS_SURFACE_RESIZE (139), SYS_ALARM (140), SYS_GETXATTR (141), SYS_SETXATTR (142).
  • SYS_CHMOD (68) / SYS_CHOWN (69) upgraded to v3 — syscall table entries 68/69 now dispatch to sys_chmod_v3 / sys_chown_v3, which perform a real read-modify-write of the on-disk directory sector via hbfs_flush_dir_entry; they also auto-upgrade the superblock to HBFS_VERSION_V3 and set HBFS_FEAT_PERMS on first use.
  • SYS_GETXATTR (141) / SYS_SETXATTR (142) — user-space interface to the HBFS v3 xattr kernel API (hbfs_xattr_get / hbfs_xattr_set). Both validate all three user pointers before touching filesystem state. SYS_SETXATTR upgrades the filesystem to v3 and sets HBFS_FEAT_XATTR in the superblock on first use; the updated directory entry (with new XATTR_LBA / XATTR_COUNT) is persisted via hbfs_save_root_dir.
  • programs/syscalls.inc — constant definitions for all 142 syscalls.
  • SYS_NANOSLEEP (132) improved — now delegates to sys_sleep after converting the timespec to PIT ticks (100 Hz); uses TASK_BLOCKED + sched_wake_sleepers when the scheduler is active, falls back to a hlt-loop in single-task context.
  • SYS_MPROTECT (123) real PTE walk — replaces previous stub; walks the two-level page directory (PDI = virt >> 22, PTI = (virt >> 12) & 0x3FF) for every page in the requested range; sets/clears PG_WRITABLE and PG_PRESENT in each PTE according to the PROT_READ / PROT_WRITE / PROT_EXEC / PROT_NONE flags; issues invlpg after each PTE update; returns EFAULT if any page is not present.
  • SYS_GETUID/GETEUID/GETGID/GETEGID/SETUID/SETGID — syscalls now read and write TCB_UID / TCB_GID fields in the running task's TCB; setuid/setgid enforce POSIX rules (root UID == 0 may set any value; non-root may only re-set their own ID).

Memory management (kernel/pmm.inc, kernel/sched.inc)

  • PMM buddy coalescing (pmm_free_coalesce) — when a page (or page range) is freed, the allocator now searches the free list of the same buddy order for the freed block's buddy partner (XOR of page number with 1 << order). On match the buddy is unlinked and the merged block is promoted to order + 1 and the coalesce loop repeats up to BUDDY_ORDERS - 1; bitmap bits are cleared as part of the same operation. pmm_free_page and pmm_free_pages both call pmm_free_coalesce instead of pmm_push_free_block, resulting in maximal free-block consolidation at every free.
  • Multi-user TCB fields — TCB_UID = 72, TCB_GID = 76 added to the Task Control Block; TCB_SIZE raised from 72 to 80 bytes. New tasks inherit UID/GID = 0 (root) via the existing rep stosd zero-initialisation in sched_create_task.
  • TCB_ALARM field + sys_alarm (SYS_ALARM = 140) — TCB_ALARM = 80 stores a PIT tick deadline (0 = no alarm); TCB_SIZE raised to 84 bytes. sched_check_alarms() is called from irq_timer on every tick and sets TCB_SIG_PEND |= (1 << SIGALRM) when the deadline is reached, then clears TCB_ALARM. sys_alarm(seconds) programs the alarm and returns the number of seconds remaining before any previously-set alarm would have fired (0 if none); passing 0 cancels any pending alarm. Child tasks created by fork do not inherit the parent's alarm. SYS_ALARM = 140 added to programs/syscalls.inc.
  • sys_access fix (SYS_ACCESS = 133) — corrected three bugs: (1) missing hbfs_load_root_dir call before hbfs_find_entry (the directory buffer could be stale); (2) wrong pushad-frame stack offset ([esp+8] = EBP instead of [esp+24] = ECX) used to read the POSIX mode argument; (3) hardcoded UID = 0 replaced with real TCB_UID / TCB_GID read from the running task's TCB via sched_get_current_task.

Networking (kernel/net.inc)

  • ICMPv6 echo reply checksum (RFC 4443) — ipv6_handle now computes the correct one's-complement checksum over the ICMPv6 pseudo-header (source address, destination address, payload length, next-header = 58) plus the full ICMPv6 payload before transmitting each echo reply; the checksum field at ICMPv6 header offset +2 is written in-place after folding the 32-bit accumulator to 16 bits.

Shell (kernel/shell.inc)

  • ls -s sort-by-size — new flag to cmd_list_dir; collects pointers to all valid HBFS directory entries into path_search_buf, insertion-sorts them descending by file size ([entry + 256]), then displays the sorted list in long format (type indicator, right-aligned 9-digit size, YYYY-MM-DD HH:MM timestamp, filename). Uses index-based array access (path_search_buf + 4 + ebx*4) with pushad/popad register discipline to avoid clobbering the VGA print register contract under NASM -O0.

Compositor IPC (kernel/ipc.inc)

  • Compositor surface API — kernel-managed pixel buffers (ipc_surface_table, SURF_MAX = 16); surfaces have id, owner PID, width/height, z-order, position, and a PMM-backed pixel buffer. ipc_surface_create / commit / destroy / move / resize implement the five new syscalls.
  • vbe_compositor_refresh — wakes the Burrows compositor task (by PID stored in burrows_compositor_pid) whenever a surface is created, committed, moved, or destroyed.
  • ipc_find_surface — helper to locate a surface entry by ID in O(SURF_MAX) time.

Package manager (tools/hbpkg.c)

  • hbpkg — self-contained C tool (compiled by make hbpkg) to create, inspect, and install .hbpkg archives. Supports create <dir> <pkg>, inspect <pkg>, and install <pkg> <dest> subcommands. Header: magic HBPKG, version, file count, and per-file records (path + size + data).

Build system (Makefile)

  • make uefi — cross-compiles UEFI loader via gnu-efi → .so → objcopy .efi.
  • make run-uefi — creates GPT+FAT ESP image and launches QEMU with OVMF.
  • make 64bit — assembles kernel64.bin + stage2-64.bin with -DKERNEL_64BIT=1.
  • make hbpkg — compiles tools/hbpkg.c to tools/hbpkg.
  • make count — now counts .c source files alongside .asm / .inc.

v9.0.0 - Buddy allocator, demand paging, fork(), HBFS v2, GUI enhancements, IPv6, TLS, POSIX msgq

Memory management (kernel/pmm.inc, kernel/paging.inc)

  • Buddy allocator — pmm.inc now implements a two-level buddy system (order 0 = 4 KB, order 9 = 2 MB) on top of the bitmap-based free-page tracker. pmm_alloc_pages(n) and pmm_free_pages(base, n) coalesce buddies on free. Page-fault handler integrated.
  • Demand paging — paging.inc adds a demand-paging region per process starting at USER_DEMAND_BASE (0x08000000). Page-fault handler (#PF via IDT vector 14) maps physical pages on first access.

Process model (kernel/sched.inc, kernel/syscall.inc)

  • SYS_FORK (103) — duplicates calling process's page-directory, stack, and register state. Returns child PID to parent, 0 to child. Child is immediately runnable. (SYS_EXEC (21) and SYS_WAITPID (92) were already present; both are used by vsh.)

File system (kernel/hbfs.inc)

  • HBFS v2 journal — 16-entry write-ahead journal records (block, old_data, new_data) before every metadata write; hbfs_journal_replay replays or discards on mount.
  • Defragmenter — hbfs_defrag compacts live blocks toward LBA 0; exposed as SYS_DEFRAG (104).
  • Limits raised — max filename length 64 B → 128 B; max open files 8 → 16.

Burrows desktop (kernel/burrows.inc)

  • Virtual desktops — 4 workspaces; Super+1..4 to switch, Super+Shift+1..4 to move a window. Active desktop stored per window; switching hides/shows without destroying state.
  • Alpha-blend — gui_alpha_blend_rect(x, y, w, h, color, alpha) porter-duff over the framebuffer; used for window shadows and notification badges. Fixed 32-bit register usage (sil/dil replaced with mov+and idiom for 32-bit NASM compatibility).
  • Edge resize — 6-pixel resize border on all four window edges; cursor changes to resize arrow in border regions.

Terminal (programs/bterm.asm)

  • 80×24 character cell grid with 200-line scrollback ring buffer.
  • ANSI SGR colour (\e[30m–\e[37m fg, \e[40m–\e[47m bg, \e[0m reset).
  • PgUp / PgDn scroll through scrollback; Home returns to bottom.

Networking (kernel/net.inc)

  • IPv6 / ICMPv6 — Ethernet type 0x86DD demux; ipv6_handle processes 40-byte fixed header; ICMPv6 echo-request/reply (types 128/129) fully handled.
  • TLS stub — SYS_TLS_CONNECT (105): EBX=ip, ECX=port, EDX=handle_ptr → EAX=0/-1. Performs TCP connect then records (ip, port) for subsequent send/recv.

Audio (kernel/ac97.inc)

  • AC'97 mixer channel: treble, bass, PCM-in gain knobs wired.
  • PCM recording: SYS_AUDIO_REC_START (106), SYS_AUDIO_REC_READ (107), SYS_AUDIO_REC_STOP (108).
  • Mixer channels: SYS_AUDIO_OPEN (109), SYS_AUDIO_WRITE (110), SYS_AUDIO_CLOSE_CHAN (111).

IPC (kernel/ipc.inc)

  • POSIX message queues — kernel-managed pool of 8 queues, 16 messages × 256 B each. SYS_MSGQ_CREATE (112), SYS_MSGQ_SEND (113), SYS_MSGQ_RECV (114), SYS_MSGQ_CLOSE (115).

New programs (v9.0.0)

  • chess — VBE 1024×768 chess game with greedy-material AI. Arrow keys to move cursor, Enter to select/place piece, R to reset, ESC to quit.
  • vsh — Veritas Shell: fork/exec model, 24-entry command history (↑/↓), built-ins cd, echo, history, uname, help, exit.
  • curl [-X POST] [-d data] host path — HTTP/1.0 GET or POST client over raw TCP. Uses SYS_DNS, SYS_SOCKET, SYS_CONNECT, SYS_SEND, SYS_RECV.
  • rec [-t secs] [-o file] — Records PCM audio via SYS_AUDIO_REC_* and writes a valid 44-byte RIFF/WAV file.
  • mix file1 file2 — Mixes two 16-bit mono WAV files sample-by-sample (clamp to ±32767) and plays the result through an AC'97 mixer channel.

Enhanced programs

  • strace — now uses SYS_FORK to trace a child process; highlights fork events in yellow; SYS_WAITPID loop monitors child exit.

Syscall table

Slots 0–115 fully wired. New additions this release: 103 (fork), 104 (defrag), 105 (tls_connect), 106–108 (audio rec), 109–111 (audio mixer), 112–115 (msgq).

v8.5.0 - Expanded graphics, audio, and I/O subsystems

New modules

  • kernel/pci.inc — Generic PCI bus enumeration (buses 0–7). Scans all devices/functions, builds a 64-entry device table. Exposes pci_find_device, pci_read_config32, pci_write_config32, pci_read_bar. New syscall SYS_PCI_FIND (101): EBX=vendor, ECX=device_id → EAX=bdf or -1.

  • kernel/ac97.inc — Intel AC'97 audio controller driver (ICH2/3/4, 8086:2415/2425/2445). Uses PCI Bus Master DMA for playback. Allocates 32-entry Buffer Descriptor List and two 32 KB ping-pong buffers. Falls back gracefully if device absent. Hooks into SYS_AUDIO_PLAY.

  • kernel/atadma.inc — ATA Bus Master IDE DMA extension. Detects Intel PIIX3/4 IDE controller (8086:7010/7111) via PCI, allocates a PRD table and a 4 KB bounce buffer. Provides atadma_read_sectors (up to 8 sectors per call). Falls back to existing PIO path if unavailable.

  • kernel/virtio.inc — VirtIO PCI legacy driver (spec 0.9.5).

    • virtio-blk (1AF4:1001/1042): virtqueue-based block device with 3-descriptor request chains and polled completion. Provides virtio_blk_read.
    • virtio-net (1AF4:1000/1041): negotiation + MAC address read.

Graphics upgrades (kernel/vbe.inc additions)

  • Bresenham line — vbe_draw_line / SYS_DRAW_LINE (95)
  • Scanline triangle fill — vbe_fill_triangle / SYS_DRAW_TRIANGLE (96)
  • Sprite blit with color key — vbe_sprite_blit / SYS_BLIT (97)
  • Dirty-rectangle tracking — vbe_dirty_present / SYS_DIRTY_PRESENT (98) Maintains the smallest bounding box of modified pixels and bulk-blits only that region from shadow buffer to LFB.
  • PSF2 bitmap font loader — SYS_PSF_LOAD (99) / SYS_PSF_CHAR (100) Loads any PSF2 font from HBFS (up to 256 KB), renders individual glyphs into the framebuffer.

Kernel wiring

  • pci_init, ac97_init, atadma_init, virtio_init called from kernel_entry after sb16_init, before burrows_init.
  • New includes added in correct dependency order.

New programs (v8.5.0)

  • more [FILE] — paging text viewer (23 lines/page; SPACE=next, ENTER=line, Q=quit).
  • pciinfo — queries SYS_PCI_FIND to list all detected PCI devices with bus:device.function addresses.
  • audiodemo — probes SB16 and AC'97 via PCI, plays a PC-speaker melody, then attempts 16-bit PCM playback via SYS_AUDIO_PLAY.
  • soundviz — SB16 chord sequence (C4, E4, G4) with an animated waveform visualizer on the 640×480 VBE framebuffer.
  • blitdemo — bouncing 16×16 color-keyed sprite via direct shadow-buffer writes.
  • gfxdemo — scrolling rainbow gradient background + bouncing square sprite with title overlay; demonstrates the shadow-buffer flip workflow.
  • gfxplasma — classic sum-of-sines plasma effect rendered as 320×240 → 2×2 blocks on the 640×480 framebuffer.
  • breakout — Breakout/Arkanoid clone: 5 × 10 bricks, three lives, LEFT/RIGHT arrows to move paddle.
  • cube — perspective-projected rotating wireframe cube using 16.16 fixed-point sine tables and SYS_DRAW_LINE.
  • julia — interactive Julia set renderer (arrow keys move c, +/- zoom, R reset).
  • mandelbrot — Mandelbrot set at 640×480×32 bpp; progressive rendering, rainbow escape-time palette.
  • sed [-n] [-e SCRIPT] [SCRIPT] [FILE] — stream editor: s///g, d, p, =, q, y///, line/regex/range addressing.
  • awk [-F SEP] 'PROG' [FILE] — pattern/action processor: $n, NR, NF, print, gsub(), sub(), /regex/, BEGIN/END blocks.
  • top — real-time process monitor using SYS_PROCLIST (all 128 slots) and SYS_MEMINFO with a used/free memory bar; refreshes every second.
  • tar c|x|t ARCHIVE [FILES] — HBTAR1.0 flat archive: create, extract, list; up to 64 files × 64 KB each.
  • nm FILE [FILE ...] — ELF32 symbol table reader: parses SHT_SYMTAB / SHT_STRTAB, prints address, type letter (T/D/B/R/U), and name.

Manual pages

  • All 16 new programs above added to man.asm with full NAME / SYNOPSIS / DESCRIPTION / CONTROLS / SEE ALSO sections.

v8.4.2 - del is now persistent across make full

Fix

  • populate.py previously re-added every program binary on every make full, silently undoing any del the user had run inside the OS.
  • Cache schema bumped to v2 with a new tombstones set. Workflow:
    1. On the first make full after a del, populate notices the cached binary is no longer present in the image, records a tombstone, and skips re-adding it.
    2. On subsequent make full runs, tombstoned binaries stay gone as long as the source .asm (and therefore the rebuilt .bin) hasn't been touched.
    3. Touching/modifying the source clears the tombstone — the binary is "revived" automatically. This preserves the developer ergonomics of "edit programs/foo.asm, run make full, see new foo".
  • Cache also self-prunes tombstones whose .bin has been removed from programs/.
  • v1 (flat dict) caches are still loaded for backward compat.

v8.4.1 - Theme actually themes now

Fixes

  • theme previously called SYS_SETCOLOR once and exited, but every kernel print path immediately restored the hard-coded COLOR_DEFAULT (0x07), so the selected theme survived only until the next character was printed.
  • Added a runtime default_color byte and vga_reset_color helper. SYS_SETCOLOR now updates both the live vga_color and the persistent default_color, and all ~22 mov byte [vga_color], COLOR_DEFAULT sites in kernel/ were converted to call vga_reset_color. vga_clear now uses the live default color too, so the screen background recolors immediately.
  • Net effect: theme amber (or any of the 8 themes) now actually changes the shell, prompt, and subsequent output for the rest of the session.

v8.4.0 - Daily Driver Pass IV

Six more userspace programs

  • roll [N | A B] generic random integer (default 1..100, one-arg = 1..N, two-arg = A..B inclusive).
  • pick item1 item2 ... picks one of the supplied tokens uniformly at random.
  • reverse <text> reverses the argument string.
  • upper <text> / lower <text> case conversion.
  • countc <text> prints chars / words / lines counts for the argument string.

Tests

  • Regression suite grows from 1534 to 1576/1576 passing.

v8.3.0 - Daily Driver Pass III

Six more userspace programs

  • stopwatch lap stopwatch (Enter = lap, q = quit); HH:MM:SS.cc precision via SYS_GETTIME.
  • countdown <secs|Nm|MM:SS> countdown timer with end-of-time beeps and Burrows notification.
  • passgen [len] [-a] random password generator (xorshift32 seeded from time XOR PID); -a restricts to alphanumerics.
  • dice [NdM] roll N dice with M sides; prints individual rolls and sum.
  • coin [N] flip one or more coins; summary heads count when N>1.
  • tip <bill> [pct] [people] bill / tip / split-by-people calculator with cents-precise math.

Tests

  • Regression suite grows from 1492 to 1534/1534 passing.

v8.2.0 - Daily Driver Pass II

Six more userspace programs

  • tldr <cmd> one-line summary lookup; tldr with no args lists every entry.
  • todo persistent todo list at /home/.todo with add and done <N>.
  • pomodoro [min] focus timer with countdown, three completion beeps, and a desktop notification.
  • morse [-p] <text> ASCII -> Morse (.-/-...); beeps each symbol on the PC speaker unless -p (print only).
  • wiki list|show|add <topic> ... personal knowledge base under /home/wiki/<topic>.txt.
  • color full 16x16 VGA attribute palette rendered straight to the framebuffer; press any key to exit.

Tests

  • Regression suite grows from 1450 to 1492/1492 passing.

v8.1.0 - Daily Driver Pass

New userspace programs (14, one per roadmap section)

  • Kernel & runtime: meminfo — free/total memory, uptime, PID.
  • Filesystem: tag — file tagging via /home/.tags.db; add/list/find.
  • Shell UX: histgrep — case-insensitive search of shell history.
  • Burrows GUI: bnotify — desktop notification with optional -c <attr>.
  • Burrows app: bcal — today + scheduled events from /home/.events.
  • Demo: plasma — animated text-mode plasma at 0xB8000.
  • Game: nim — single-pile misère Nim with optimal AI.
  • Dev tooling: mkprog — generates a runnable <name>.asm skeleton.
  • Networking: dnslook — SYS_DNS wrapper printing dotted-quad IPs.
  • Sound: play — token-driven note sequencer for the PC speaker.
  • Productivity: journal — appends YYYY-MM-DD HH:MM entries to /home/journal.txt.
  • Polish: theme — 8 named color themes, persisted to /home/.theme.
  • Documentation: tutorial — 8-page interactive welcome tour.
  • Distribution: pkginfo — OS / version / arch / RAM / uptime banner.

Manual pages

  • man rewrite: 49 baked-in topics with case-insensitive lookup, man -l listing and man -k <kw> keyword search; falls back to /docs/man/<topic>.txt if a topic is not baked in.
  • New man pages added for every program above plus intro, shell, files, burrows, syscalls, hbfs, keys, credits.

Tests

  • Regression suite grows from 1352 to 1450/1450 passing.

v8.0.0 - Hardening Pass

Kernel safety

  • VBE / framebuffer: bounds-checked vbe_putpixel and full rect clipping in vbe_fill_rect; mode validation in vbe_set_mode (320..1920 × 200..1200, bpp ∈ {16,24,32}); LFB mapping page count derived from the validated mode and capped; shadow buffer pages now freed before reallocation; .fb_drawtext capped at 4 KB to prevent runaway loops.
  • Syscall pointer validation: new validate_user_ptr helper guards user-supplied pointers in sys_print, sys_exec_call, and sys_proclist. Range checked against [PROGRAM_BASE, USER_PTR_MAX).
  • Paging / PMM: paging_map_page now drops its prologue pushes on the alloc-failure path (was popad'ing with 16 stale bytes on the stack); pmm_alloc_pages contiguity scan bounded against the bitmap size.
  • IPC / scheduler: pipe PIPE_COUNT check + cursor update made atomic so concurrent readers/writers can't underflow or over-fill the ring; sys_sigmask read-modify-write wrapped in CLI/STI.
  • Drivers: ATA read/write reject LBA outside [0, ata_total_sectors); RTL8139 driver refuses BAR0 == 0; HBFS filename compare capped at 252 to handle non-NUL-terminated entries; shell Ctrl+W keeps line_len in sync with the cursor.

User-program safety

  • wget hostname / path / outfile copy loops capped at the buffer size (256 / 512 / 128 bytes).
  • programs/lib/vbe.inc vbe_fill_rect now clips against fb_width / fb_height, mirroring the kernel-side fix.

Build, populate, tooling

  • Portable NPROC detection (nproc → sysctl → getconf → 4).
  • kernel_sectors.inc generation hard-fails if the kernel exceeds 2048 sectors (1 MB), preventing silent overflow of the stage-2 load buffer.
  • populate.py now prints a warning when a filename is truncated to 252 bytes instead of silently shortening.
  • New make sanitize target builds with KERNEL_DEBUG_BOUNDS=1 for CI-style hostile-bounds nightlies.
  • Experimental/tools/packet_fuzz.py — dependency-free fuzz frame generator (Eth runts, ARP/IPv4/TCP/UDP malformations, random garbage) for offline replay against kernel/net.inc parsers.

Documentation

  • docs/TECHNICAL_REFERENCE.md GDT table corrected: 0xCF flags row now reads "32-bit, 4K gran" (was mislabelled "64-bit").

v7.5.0 - BASIC Compiler & Interpreter Upgrade

Added

  • basicc — new BASIC-to-x86 compiler. Compiles a BASIC source file (.bas) to a flat x86-32 native binary that runs directly on Mellivora OS. Usage: basicc source.bas output.bin. Supports:

    • Numeric variables A–Z (32-bit integer)
    • Full arithmetic: +, -, *, /, MOD
    • Bitwise / logical: AND, OR, XOR, NOT
    • Relational comparisons: =, <>, <, >, <=, >=
    • PRINT with string literals and numeric expressions, ; and , separators
    • INPUT with optional prompt string
    • LET var = expr and bare var = expr assignment
    • IF ... THEN ... [ELSE ...] with inline statements or line numbers
    • GOTO / GOSUB / RETURN (with forward-reference fixup table)
    • FOR var = start TO end [STEP step] / NEXT (up to 16 nested loops)
    • WHILE ... WEND (up to 64 nested)
    • END, STOP, CLS, BEEP, SLEEP expr
    • Multi-statement lines via :
    • REM comments
    • Output binary is a self-contained flat x86 executable starting at 0x200000; no runtime library required.

  • samples/fib.bas — Fibonacci sequence sample program for basicc.

  • samples/hello.bas — minimal Hello World sample for basicc.

Changed

  • basic (v3.1) — upgraded the GW-BASIC interpreter:
    • Added TRON / TROFF — execution trace mode prints [linenum] before each statement.
    • Added STOP / CONT — stop mid-program and continue.
    • Added HEX$(n) and OCT$(n) string functions.
    • Updated HELP listing and version banner to 3.1.

v7.4.0 - BASIC Expansion

Changed

  • basic — expanded from a tiny integer-only interpreter into a much larger GW-BASIC-style environment. Added string variables and string functions, LINE INPUT, IF ... THEN ... ELSE, WHILE/WEND, ON ... GOTO/GOSUB, DATA/READ/RESTORE, LOCATE, SWAP, TAB() / SPC(), broader math functions, multi-statement lines with :, a HELP command, larger program storage, and improved runtime errors.

v7.3.0 - Bug Fixes & Housekeeping

Fixed

  • pacman, frogger, sudoku — black-screen bug: all three were drawing into the VBE shadow buffer but never calling VBE_GAME_PRESENT to blit it to the live framebuffer. Screen now renders correctly on launch.

Removed

  • reversi — removed from the distribution. The VBE Reversi/Othello experience is covered by iago, which has a full board renderer, greedy-AI opponent, and persistent win counter.

v7.2.0 - Arcade Authenticity Pass

Added

  • frogger — Classic road-and-river crossing. 11 lanes (5 river + median + 5 road), drifting logs/turtles you must ride, oncoming cars/trucks at varying speeds, 5 home slots to fill. 3 lives, persistent high score saved to /scores/frogger.

Changed

  • galaga — Major arcade-faithful overhaul:
    • Enemies now dive-bomb out of the formation in attack runs instead of marching wall-to-wall.
    • Diving enemies fire bullets that can hit the player.
    • Formation gently sways side-to-side as a unit.
    • Player respawns with brief invulnerability flicker when hit; the lives counter is finally meaningful (game-over only at 0).
    • Arcade 2-shot limit on player bullets.
    • Arcade-style scoring: bug 50, moth 80, boss 150 — double when killed mid-dive.
    • Stars now scroll downward for parallax.
    • "STAGE N" intro banner between levels.

v7.1.0 - New Arcade Games

Added

  • pacman — Pac-Man-style 21x21 maze chase. Eat dots (10 pts) and power pellets (50 pts) while avoiding 4 ghosts. Power pellets frighten ghosts for ~6 sec, allowing you to eat them (200 pts) and send them back to a corner. Persistent high score saved to /scores/pacman; win/lose SFX cues at end of round.

v7.0.1 - Sudoku

Added

  • sudoku — brand-new 9x9 Sudoku puzzle game.
    • 4-puzzle bank cycled per session via SYS_GETTIME.
    • Cursor navigation (arrows), digit entry (1–9), clear (0/Space).
    • Real-time row/column/3x3-box conflict highlighting in red.
    • H hint key fills one missing cell from the solution.
    • Persistent solve count saved to /scores/sudoku; win SFX on solve.

v7.0.0 - The Hercules Release (Phases 7-8 of Hercules overhaul)

Release summary

Closes the eight-phase Hercules overhaul that began at v6.1. Across all phases the project gained shared VBE UI libraries, a universal quit-key sweep, the audio.inc + highscore.inc libraries (v6.5), and persistent high-score wiring for 28 games. v7.0.0 promotes the result to a stable release.

Bumped

  • Boot banner, version_text, and shell help in kernel/data.inc updated from v6.5 → v7.0 ("The Hercules Release").
  • bsysmon "OS" field, neofetch OS + shell strings, README directory tree, and docs/INSTALL.md all bumped to v7.0.
  • "(v6.5+)" annotations in API docs are kept as historical "added-in" markers for the audio + highscore libraries.

Verified

  • Full clean rebuild (make full) populates 203 files cleanly with no NASM warnings.
  • All 28 wired games still build and link without changes.
  • No lingering v3.x / v4.x / v5.x version strings in the live banners.

v6.5.0 - Audio + High-Score Libraries (Phase 6 of Hercules overhaul)

New shared libraries

  • programs/lib/audio.inc — note table (NOTE_C2..NOTE_C7), audio_note, audio_rest, audio_play_score (byte-packed melody), audio_play_score_w (word-packed for full Hz range), and stock SFX cues audio_sfx_click/_ok/_error/_win/_lose. All entry points preserve registers; built on SYS_BEEP (24).
  • programs/lib/highscore.inc — hs_load, hs_save, hs_update. Each game's high score lives in /scores/<name> as a single little-endian dword. hs_update writes only when the candidate beats the stored value. The /scores directory is auto-created on first write.

Wired into existing games

  • tetris — loads/saves high score, displays "High:" under "Score:" in the HUD, plays audio_sfx_lose once on game-over.
  • 2048 — splits the score panel into SCORE + HIGH boxes, persists high score, plays loss SFX on game-over.
  • snake — adds HIGH: to the score bar, persists high score, plays loss SFX in show_game_over.
  • breakout — adds HIGH: to the HUD band, persists high score, plays loss SFX once when lives reach 0.
  • simon — shows HIGH line under the SCORE on the game-over banner, persists best round reached, plays loss SFX once.
  • galaga — adds High Score: line to the game-over panel, persists high score, plays loss SFX.
  • mastermind — best-game persisted as inverse of guesses-needed (so hs_update's max-wins semantic still picks the better record); win/lose SFX cues. Best record loaded once at start.
  • hangman — running WINS: counter persisted across runs; win/lose SFX cues fired once per round.
  • tictactoe — persistent WINS: counter (player vs CPU) shown under the header; win/lose/draw SFX cues fired once per game.
  • connect4 — wins counter now persists across reboots (loaded into the existing on-screen WINS panel); win/lose/draw SFX cues.
  • reversi — wins (BLACK > WHITE) persist across runs; win/lose/tie SFX cues fired once at end-of-game.
  • wordle — total solved-words counter persists across runs; solve / fail SFX cues.
  • mine (Minesweeper) — total cleared-board wins persist across runs; safe-clear / mine-trigger SFX cues.
  • puzzle15 — total solved-puzzles counter persists across runs; win SFX fires once on each solve.
  • lights (Lights Out) — total solved-boards counter persists across runs; win SFX cues on each solve.
  • sokoban — total cleared-levels counter persists across runs; win SFX cues each time a level is cleared.
  • guess (number guessing) — total correct-guess counter persists across runs; win SFX cues on correct answer.
  • battleship — total wins persist across runs; win SFX on victory, lose SFX on defeat.
  • blackjack — total dealer-beating rounds persist across runs; win/lose SFX cues on each settled hand.
  • nim (misere) — total wins persist across runs (saved to /scores/nim after each AI takes the last); win/lose SFX cues.
  • checkers — total wins (player=red) persist across runs; win/lose SFX cues fired once when the board is decided.
  • iago (Reversi variant, player=BLACK) — total wins persist across runs; win/lose/tie SFX cues fired once at end-of-game.
  • solitaire — total completed games persist across runs; win SFX fires once when all 4 foundations are filled.
  • pipes — high score persists across runs (best score is kept); win/lose SFX cues on flow reaching drain or going dry.
  • lunar — total safe landings persist across runs (saved to /scores/lunar after every soft touchdown); win SFX on safe landing, lose SFX on crash.
  • kingdom — best end-of-reign score persists across runs; win fanfare SFX on completing 10 years, lose SFX on collapse.
  • rogue — best XP persists across runs (written when the player dies); lose SFX on death.
  • outbreak — best total-vaccinated count persists across runs; win SFX on outbreak defeated, lose SFX on collapse.

ps modernized

  • Now scans all 128 scheduler slots (was 16) and uses the v4.0 expanded 48-byte SYS_PROCLIST ABI: shows new PRI (priority) column and a 16-char NAME column.
  • All five live task states have distinct color and label: READY (green), RUNNING (white), BLOCKED (blue), STOPPED (magenta), ZOMBIE (red).
  • Footer now prints a state breakdown: Active: N Running: r Ready: r Blocked: b Stopped: s Zombie: z.

bsysmon enhancements

  • Live memory — Memory: now reports USED / TOTAL MB (PCT%) from SYS_MEMINFO (67) plus a 200-pixel horizontal usage bar that turns yellow at ≥70 % and red at ≥90 %.
  • Uptime — new Uptime: Hh Mm Ss line derived from SYS_GETTIME ticks (PIT @ 100 Hz).
  • Process count — new Procs: N active line that walks the 128-slot task table via SYS_PROCLIST (66).
  • Auto-refresh — main loop now sleeps 50 ticks (~500 ms) between redraws when no input is pending, so all live values update without user interaction.
  • Window resized to 360×340 to fit the new rows; OS: line bumped to v6.5.

Documentation

  • docs/API_REFERENCE.md — added Quick Start entries and reference tables for both new libraries.

v6.4.0 - Universal Quit-Key Sweep (Phase 5 of Hercules overhaul)

Universal Q + ESC quit

Per docs/STYLE_GUIDE.md, every interactive VBE game must accept ESC, lowercase q, AND uppercase Q to quit. This release brings 24 games into compliance:

  • Added uppercase Q (already had ESC + q): 2048, battleship, blackjack, checkers, chess, connect4, guess, hangman, iago, lights, lunar, mastermind, mine, nim, pipes, puzzle15, reversi, simon, sokoban, solitaire
  • Added q and Q (had only ESC): breakout, maze
  • Added ESC (had q/Q but no ESC): pong
  • Added Q and converted raw 27 → KEY_ESC style consistency: galaga, rogue, snake
  • Added q/Q to main play loop (had ESC only): outbreak (title + action loop), kingdom (title screen)

Demo/screensaver programs (doomfire, matrix, rain, starfield, spritetest) intentionally retain "press any key to exit" behavior.

Phase 4 — VBE conversion of adventure.asm and neurovault.asm

Decision: not converting. Both are interactive-fiction text adventures where text-mode terminal flow IS the appropriate medium. Forcing them into a framebuffer would only simulate a terminal inside a pixel surface — strictly worse UX for no gain. Their existing VGA text presentation remains the right call. Future polish will be limited to text-mode banner/prompt consistency.

v6.3.0 - Style Migration & Doc Refresh (Phases 2-3 of Hercules overhaul)

Style migration

  • tictactoe.asm — pilot migration to the shared style infrastructure:
    • Color literals replaced with MV_* aliases from lib/palette.inc.
    • Title and status text now drawn by vbe_ui_header_bar and vbe_ui_status_bar from lib/vbe_ui.inc.
    • R/r now restarts the game at any time (not just after game-over), matching the style-guide convention.

Documentation refresh

  • docs/PROGRAMMING_GUIDE.md:
    • Removed 7 phantom syscall definitions (SYS_SEM_CREATE, SYS_SEM_WAIT, SYS_SEM_POST, SYS_SEM_CLOSE, SYS_WAITPID, SYS_GETMTIME, SYS_SETMTIME) that were never implemented.
    • Fixed VBE example resolution from 640×480 to 1024×768 (matches the actual VBE_GAME_INIT macro).
    • Added a new Shared VBE UI Library (v6.1+) section documenting lib/palette.inc and lib/vbe_ui.inc, with cross-reference to docs/STYLE_GUIDE.md.
    • Updated table of contents.
  • docs/API_REFERENCE.md:
    • Fixed VBE example resolution from 640×480 to 1024×768.
    • Added lib/vbe.inc, lib/font.inc, lib/vbe_game.inc, lib/palette.inc, and lib/vbe_ui.inc to the Quick Start include list, with a note pointing to STYLE_GUIDE.md.
  • docs/INSTALL.md:
    • Project structure now reflects current state (~290 programs, current version v6.2.0).

Audited-clean (no doc changes needed)

docs/INSTALL.md, docs/NETWORKING_GUIDE.md, docs/TECHNICAL_REFERENCE.md, docs/TUTORIAL.md, docs/USER_GUIDE.md were all reviewed and found to match the current code state.

v6.2.0 - Bug Sweep (Phase 1 of Hercules overhaul)

Initialization-safety fixes (section .bss → dd 0)

NASM -f bin mode places .bss labels past the end of the program binary, where the kernel loader does NOT zero memory. Variables declared via resd/resb therefore start with whatever junk was left by the previous program. Three programs had counters/buffers in .bss that could be read-before-written; converted them to inline dd 0 / times N db 0 so they're guaranteed zero at startup:

  • tetris.asm — fb_addr, fb_pitch, num_buf
  • typist.asm — 14 dd counters + input_buf (MAX_INPUT bytes)
  • bnotes.asm — win_id, cursor_pos, draw_col, note_text

(See docs/STYLE_GUIDE.md §1.2 for the full rule.)

Audit pass — clean

Audited 20+ programs (VBE games, Burrows GUI apps, CLI utilities) for common bug patterns; the following were found to be solid: simon, bedit, bcalc, bsysmon, bpaint, bsheet, bplayer, bsettings, bview, bterm, bhive, grep, sed, sort, cp, find, wget, dig, asm, bc, diff, tictactoe.

The flip-logic in iago.asm was re-audited: logic is correct (the previously-fixed reversi.asm was the source of the visible flip bug).

Quality-of-life: universal Q/ESC quit

  • tetris.asm — game-over screen now also accepts Q/q
  • wordle.asm — main loop now also accepts Q/q

v6.1.0 - Foundation (Phase 0 of Hercules overhaul)

New shared infrastructure

  • programs/lib/palette.inc: Project-wide color palette. Single source of truth for MV_BG_*, MV_FG_*, MV_ACCENT_*, MV_STATUS_*, MV_CURSOR, MV_BOARD_* and other UI tones. Programs should alias these (e.g. COL_BG equ MV_BG_DARK) instead of hard-coding hex literals.
  • programs/lib/vbe_ui.inc: Shared VBE UI widgets used by all games:
    • vbe_ui_header_bar — top title band
    • vbe_ui_status_bar — bottom hint band
    • vbe_ui_modal — centered dialog (game-over, help, info)
    • vbe_ui_input_line — decimal-number input widget
  • docs/STYLE_GUIDE.md: New authoritative cross-program style guide documenting program skeleton, calling conventions, syscall rules, VBE layout zones, key-binding standards, the flat-binary BSS rule, the CLI conventions, the Burrows GUI conventions, the uppercase-string rule, and the per-commit code-quality checklist.

Cleanup

  • Removed stale .bak files: edit.asm.bak, blackjack.asm.bak, tcc.asm.bak, outbreak.asm.bak (~210 KB total).

Game logic fixes

  • reversi.asm: Fixed two flip-counting bugs that produced incorrect flips and false "invalid move" rejections.
    • count_dir: dotted-local labels .dr/.dc resolved to the wrong function's locals (always 0). Qualified them as [count_flips.dr] / [count_flips.dc].
    • flip_dir: ECX (the flip counter) was being clobbered by a load of do_move.player mid-loop. Wrapped the board write with push ecx / pop ecx.

kingdom.asm — VBE conversion

  • Completed full VGA→VBE conversion (~2400 lines). Replaced text-mode phase screens, status display, mini-bars, and number input with native VBE widgets. Migrated from section .bss to flat-binary safe storage. All game strings uppercased to match the 5×7 bitmap font glyph set.

v6.0.0 - The Pixel Release

Kernel — VBE Double Buffering (kernel/vbe.inc)

  • Shadow buffer double buffering: SYS_FRAMEBUF/1 (set mode) now allocates a PMM-backed shadow buffer the same size as the framebuffer. Programs render into the shadow buffer (returned by SYS_FRAMEBUF/0) rather than the real LFB, eliminating tearing.
  • SYS_FRAMEBUF/4 — present frame: New sub-function blits the full shadow buffer to the LFB with a single rep movsd. Call once per frame after all rendering is complete.
  • Size-aware reallocation: vbe_shadow_pages tracks the allocated page count. When a new mode is set that requires more pages than the current allocation, the shadow buffer is reallocated. Prevents crashes where a 640×480 game's undersized buffer was reused for a 1024×768 program.
  • Vsync hang fix: Removed the port 0x3DA vertical-blank poll loop from the present path. The VGA input status register bit 3 does not toggle in QEMU BGA mode, causing an infinite kernel-mode hang. The blit now runs unconditionally.

Programs — Sprite Library (programs/sprite.inc)

  • New file programs/sprite.inc: Reusable sprite drawing library for VBE programs.
    • sprite_draw (EBX=x, ECX=y, ESI=sprite_ptr): draw with per-pixel alpha (alpha=0 → skip).
    • sprite_draw_opaque (EBX=x, ECX=y, ESI=sprite_ptr): draw ignoring alpha — fastest path.
    • sprite_draw_key (EBX=x, ECX=y, ESI=sprite_ptr, EDI=key): color-key transparency.
    • sprite_draw_scaled (EBX=x, ECX=y, ESI=sprite_ptr, EDX=shift): nearest-neighbour scale by 2^shift (e.g. EDX=1 → 2×, EDX=2 → 4×).
    • SPRITE_BEGIN name, width, height / SPRITE_END macros for inline sprite data.
    • Sprite pixel format: dd width, height then width*height pixels as 0xAARRGGBB.

Programs — Galaga Sprites (programs/galaga_sprites.inc)

  • New file programs/galaga_sprites.inc: Pixel-art sprite data for galaga. Five sprites defined with the sprite.inc format: spr_player (24×16), spr_bug (20×12), spr_moth (20×12), spr_boss (20×12), spr_bullet (3×12). Transparent pixels use alpha=0x00.

Programs — Sprite Test (programs/spritetest.asm)

  • New file programs/spritetest.asm: Interactive test program demonstrating all four sprite.inc routines side by side in a 640×480×32 VBE window.

Programs — VBE Game Fixes

  • programs/galaga.asm: Replaced direct pixel-fill rendering with sprite.inc calls for the player ship, enemy bugs/moths/boss, and bullets. Added SYS_FRAMEBUF/4 present call in the main game loop for double-buffered output.
  • programs/doomfire.asm, programs/life.asm, programs/pong.asm, programs/snake.asm, programs/tetris.asm: Added SYS_FRAMEBUF/4 present call at the end of each frame to make rendered output visible when double buffering is active.

Build & Tests

  • kernel_sectors.inc: Corrected KERNEL_SECTORS value to match actual kernel binary size.

v5.0.0 - The Hornet Release

Kernel — Semaphores (kernel/ipc.inc)

  • SYS_SEM_CREATE (#88): Create a counting semaphore with an initial value. Returns a semaphore ID (0–7) or -1 on failure.
  • SYS_SEM_WAIT (#89): Decrement (P/wait) a semaphore. If the value is 0, yields up to 500 times before returning -1 (non-blocking style consistent with pipe I/O).
  • SYS_SEM_POST (#90): Increment (V/post) a semaphore.
  • SYS_SEM_CLOSE (#91): Release a semaphore slot.
  • Up to 8 semaphores simultaneously. Semaphore state initialised in ipc_init.

Kernel — Synchronous Wait (kernel/sched.inc)

  • TASK_ZOMBIE state (5): Tasks that call sys_exit now enter a zombie state instead of being freed immediately, preserving their slot until reaped by a parent.
  • SYS_WAITPID (#92): Wait for a task by PID. Yields up to 2000 times polling for task completion, then reaps the zombie and returns its exit code. Returns -1 if the PID is not found.

Kernel — File Timestamps (kernel/hbfs.inc)

  • SYS_GETMTIME (#93): Query a file's timestamps. Returns packed RTC DIRENT_MODIFIED timestamp in EAX and DIRENT_CREATED timestamp in ECX.
  • SYS_SETMTIME (#94): Update a file's DIRENT_MODIFIED timestamp. Pass ECX=0 to use the current RTC time.

Shell — Ctrl+R Reverse History Search (kernel/shell.inc)

  • Incremental reverse-i-search: Press Ctrl+R at the shell prompt to start an interactive history search.
  • Shows (reverse-i-search)\QUERY': MATCH` while typing.
  • Backspace removes the last search character and re-searches.
  • Enter copies the matched command to the input line and executes it.
  • Escape / Ctrl+C cancels and returns to an empty prompt.

Batch Scripts — Structured Control Flow (kernel/util.inc)

  • if exist FILENAME cmd: Test for file existence. Works with the not modifier (if not exist ...).
  • if "STR1"=="STR2" cmd: String comparison. Supports not modifier.
  • Block if / else / endif: Multi-line conditional blocks. When an if line has no inline command the following lines form the block body; an optional else block is executed when the condition is false; endif closes the block. Nested if/endif pairs are handled correctly.
  • for %%x in (a b c) do cmd: Single-line for loop. Iterates over a space-separated list; %%x in the command template is substituted with each value in turn.
  • else and endif are now recognised as batch directives in batch_run_loop.

New Programs

  • strace: Syscall trace wrapper. Usage: strace PROGRAM [args]. Records the dmesg ring-buffer depth before running the target program and dumps all new log entries added during the run, providing a lightweight activity trace.
  • patch: Apply unified-style diff output to a file. Usage: patch FILE PATCHFILE. The patch file is the output of the diff utility (< = remove, > = insert). Applies all hunks and reports how many could not be matched.

Syscall Constants (programs/syscalls.inc)

  • Added constants for all v5.0 syscalls: SYS_SEM_CREATE through SYS_SETMTIME (88–94).

v4.0.0 - The Titan Release

Kernel — Priority Scheduler (kernel/sched.inc)

  • Priority-based scheduling: Replaced round-robin with 4-level priority scheduling (HIGH, NORMAL, LOW, IDLE). Higher priority tasks are selected first; equal priority tasks use round-robin for fairness.
  • 64 tasks max: Doubled from 32 to 64 concurrent tasks (MAX_TASKS).
  • Expanded TCB: Task Control Block expanded from 32 to 64 bytes with new fields:
    • TCB_NAME (16 bytes): Human-readable task name
    • TCB_SIG_PEND / TCB_SIG_MASK: Signal pending/mask bitmasks
    • TCB_PGID: Process group ID
    • TCB_EXIT_CODE: Task exit code
  • TASK_STOPPED state: New state (4) for signal-stopped tasks (SIGTSTP/Ctrl+Z).
  • sys_proclist expanded: Output buffer expanded from 16 to 48 bytes, now includes priority, PGID, pending signals, exit code, and task name.

Kernel — Signals (kernel/sched.inc)

  • POSIX-style signals: 9 signal types implemented: SIGINT (2), SIGKILL (9), SIGUSR1 (10), SIGUSR2 (12), SIGALRM (14), SIGTERM (15), SIGCHLD (17), SIGTSTP (20), SIGCONT (25).
  • SYS_SIGNAL (#74): Send any signal to a task by PID. SIGKILL forcibly terminates, SIGTSTP stops, SIGCONT resumes, SIGINT/SIGTERM terminate.
  • SYS_SIGMASK (#77): Get/set/block/unblock signal mask. 4 operations: get, set, block (OR), unblock (AND NOT).
  • Signal masking: Tasks can mask signals via bitmask; masked signals are queued as pending.

Kernel — New Syscalls (kernel/syscall.inc)

  • 8 new syscalls (72–79), bringing total to 80:
    • SYS_SETPRIORITY (#72): Set task priority by PID
    • SYS_GETPRIORITY (#73): Get task priority by PID
    • SYS_SIGNAL (#74): Send signal to task
    • SYS_SETPGID (#75): Set process group ID
    • SYS_GETPGID (#76): Get process group ID
    • SYS_SIGMASK (#77): Signal mask operations
    • SYS_TASKNAME (#78): Set task name string
    • SYS_REALLOC (#79): Reallocate memory block

Kernel — Memory (kernel/syscall.inc)

  • SYS_REALLOC (#79): New syscall for reallocating memory — allocates new block, copies data, returns new pointer. Supports NULL pointer (fresh allocation).

Shell — Enhanced Line Editing (kernel/shell.inc)

  • Ctrl+A: Move cursor to beginning of line
  • Ctrl+E: Move cursor to end of line
  • Ctrl+U: Kill entire input line
  • Ctrl+W: Delete previous word (skip spaces, then delete word)
  • Ctrl+L: Clear screen and redraw prompt with current input
  • 128 history entries: Doubled from 64

Shell — New Commands (kernel/shell.inc)

  • ps: List all running tasks with PID, state, priority, and name
  • jobs: List background jobs (alias for ps)
  • kill <pid> [signal]: Send signal to task (default: SIGTERM)
  • bg <pid>: Resume stopped task in background (sends SIGCONT)
  • fg <pid>: Resume stopped task in foreground (sends SIGCONT)
  • nice <priority> <command>: Run command at specified priority level (0=HIGH, 1=NORMAL, 2=LOW, 3=IDLE)
  • export NAME=VALUE: Export environment variable (synonym for set)
  • source <file> / . <file>: Execute batch script in current shell context

Shell — Capacity Increases

  • 32 environment variables: Doubled from 16
  • 128 history entries: Doubled from 64

Programs — Userland Updates (programs/syscalls.inc)

  • All 8 new v4.0 syscall numbers added to shared header
  • Priority level constants (PRIO_HIGH through PRIO_IDLE)
  • Signal number constants (SIGINT through SIGCONT)

Version & Branding

  • Version bumped to v4.0.0 "The Titan Release"
  • Shell version bumped to HB Lair v3.0
  • Updated ver output: 80 syscalls, priority scheduler, signal info, enhanced shell shortcuts
  • Updated help text with all new commands and shortcuts

v3.0.1 - Bug Fixes: Sleep Regression, Neofetch, Pipe Race, Permissions UI

Kernel — Scheduler (kernel/sched.inc)

  • sys_sleep HLT fallback: In v3.0.0 the SYS_SLEEP rewrite made sleep a no-op when task_count == 0 (normal shell / single-program context). This broke 29 programs that use SYS_SLEEP for timing, animation frame-rates, and CPU-yield poll loops (clock, galaga, doomfire, matrix, rain, ntpd, serial, etc.). Fixed: when no scheduler tasks are running, sys_sleep falls back to the original HLT-based busy-wait loop so timing is preserved.

Kernel — IPC (kernel/ipc.inc)

  • pipe_retry_count race condition: The retry counter in sys_pipe_read was a global static variable (dd 0). Under preemptive multitasking two tasks blocking on separate pipes could clobber each other's count, causing infinite waits. Fixed by moving the counter to a register (EAX) local to each call — the global is removed.

Kernel — Filesystem (kernel/hbfs.inc)

  • sys_symlink dead code: Two dead mov edi, ... instructions preceded the correct mov edi, [esp+24] line, producing confusing assembly. Removed the two stale lines; behavior is unchanged.

Shell — New Commands (kernel/shell.inc, kernel/data.inc)

  • chmod <octal> <filename>: New shell command wrapping SYS_CHMOD (#68). Parses an octal permission value (e.g. chmod 755 myprog) and updates DIRENT_PERMS. Returns success/failure message.
  • chown <uid> <filename>: New shell command wrapping SYS_CHOWN (#69). Parses a decimal UID and updates DIRENT_OWNER.
  • stat permission display: The stat command now shows two additional lines: Perms: rwxrwxrwx (octal) and Owner: <uid>, reading from DIRENT_PERMS and DIRENT_OWNER respectively. Previously these fields were stored on disk but never displayed.

Programs — Display Fix (programs/neofetch.asm)

  • Logo null terminators: Each logo_art line was 32 bytes with no null terminator. SYS_PRINT (vga_print) scans until null, so every logo line printed the entire remaining logo blob as one continuous string. Fixed by adding a null byte to each line (33 bytes/line) and updating the stride calculation from shl eax, 5 to imul eax, 33. Logo now renders correctly.

v3.0.0 - Kernel Overhaul, Filesystem Permissions, TCP Backlog & 4 New Syscalls

Kernel — Syscall Dispatch (kernel/syscall.inc)

  • O(1) jump table: Replaced 68-entry linear cmp/je chain with a 128-entry indexed jump table (jmp [syscall_table + eax * 4]). Average dispatch time reduced from ~34 comparisons to 1 lookup.
  • Extensible: Reserved slots 72–127 for future syscalls; unused entries point to a safe error handler.

Kernel — Scheduler Enhancements (kernel/sched.inc)

  • TASK_BLOCKED state (state 3): New task state for sleeping/waiting tasks, automatically skipped by round-robin scanner.
  • sys_sleep (SYS_SLEEP #16): Rewritten from busy-wait HLT loop to proper blocking — sets TASK_BLOCKED, stores wakeup tick in TCB_WAKEUP, yields CPU to other tasks.
  • sched_wake_sleepers: Called every PIT tick from irq_timer; scans all blocked tasks and wakes those whose wakeup tick has elapsed.
  • TCB_PRIORITY (offset 24) and TCB_WAKEUP (offset 28): New fields replacing reserved padding.
  • MAX_TASKS doubled from 16 to 32.

Kernel — IPC Pipe Fix (kernel/ipc.inc)

  • Non-spinning pipe reads: sys_pipe_read now yields CPU up to 200 times when the pipe buffer is empty, instead of immediately returning 0 bytes. Eliminates 100% CPU polling loops in callers.
  • pipe_wake_waiter stub: Preparation for future proper wait-queue integration on pipe write.

Kernel — ISR / IRQ Hardening (kernel/isr.inc)

  • Timer context switch CLI: Added defensive CLI before the critical ESP-swap section in irq_timer. Prevents potential nested-interrupt corruption if gate type ever changes.
  • Wake sleepers on tick: irq_timer now calls sched_wake_sleepers every tick to unblock sleeping tasks.

Kernel — Page Fault Handler (kernel/paging.inc)

  • Human-readable error codes: Page fault handler now parses error code bits and prints cause: [not present]/[protection], [read]/[write], [supervisor]/[user].

Filesystem — Permissions & Symlinks (kernel/hbfs.inc)

  • File permissions (DIRENT_PERMS, offset 276): 9-bit Unix-style rwxrwxrwx stored in previously-reserved directory entry bytes. New files default to 0777.
  • File ownership (DIRENT_OWNER, offset 278): 16-bit owner UID per file.
  • SYS_CHMOD (#68): Change file permission bits.
  • SYS_CHOWN (#69): Change file owner UID.
  • SYS_SYMLINK (#70): Create symbolic link (file type FTYPE_LINK=5, target path stored as file data).
  • SYS_READLINK (#71): Read symbolic link target path.

Networking — TCP Accept Backlog (kernel/net.inc)

  • Child socket allocation: When a SYN arrives on a LISTEN socket, a NEW child socket is allocated. The parent stays in TCP_LISTEN for more connections — enables multiple simultaneous accepts.
  • TCP SYN_RCVD state handler: Added missing state machine handler for TCP_SYN_RCVD. When the final ACK of the 3-way handshake arrives, properly transitions child socket to TCP_ESTABLISHED. This fixes a bug where server-side TCP connections could never complete.
  • Child socket resolution: tcp_handle now scans for child sockets matching remote IP/port before dispatching, ensuring handshake packets reach the correct socket.
  • SOCK_PARENT field (offset 68): Tracks which listening socket spawned each child.

Networking — UDP Checksum (kernel/net.inc)

  • RFC 768 checksum: udp_send now computes a proper UDP checksum over the pseudo-header (source IP, dest IP, protocol, length) plus UDP header and payload, replacing the previous hardcoded zero.

Programs & User-Space

  • syscalls.inc: Added SYS_CHMOD (#68), SYS_CHOWN (#69), SYS_SYMLINK (#70), SYS_READLINK (#71) for user programs.
  • Version strings updated across: neofetch, uname, bterm, screensaver, MOTD, Burrows About dialog.

Build & Tests

  • All 45 tests passing (syscall consistency, HBFS layout, listing validation).
  • 169 files populated in HBFS image.

v2.2.0 - IPC, Audio, Screensavers, 52 New Programs & Bug Fixes

Kernel — Inter-Process Communication (kernel/ipc.inc)

  • Pipes: 8 concurrent pipes, 4 KB circular buffer each, with SYS_PIPE_CREATE, SYS_PIPE_WRITE, SYS_PIPE_READ, SYS_PIPE_CLOSE (syscalls 60–63).
  • Shared memory: 4 regions, 4 KB each, keyed access via SYS_SHMGET and SYS_SHMADDR (syscalls 64–65).

Kernel — Sound Blaster 16 Audio Driver (kernel/sb16.inc)

  • ISA DMA playback via SB16 DSP (base port 0x220, IRQ 5, DMA channels 1/5).
  • Supports 8-bit and 16-bit PCM, mono/stereo, configurable sample rate.
  • Three syscalls: SYS_AUDIO_PLAY (50), SYS_AUDIO_STOP (51), SYS_AUDIO_STATUS (52).

Kernel — Process Management

  • SYS_KILL (53): Terminate a task by PID.
  • SYS_GETPID (54): Get current task PID.
  • SYS_PROCLIST (66): Query task table slots (0–15).
  • SYS_MEMINFO (67): Report free/total physical pages.

Kernel — GUI Enhancements

  • Clipboard: SYS_CLIP_COPY (55) and SYS_CLIP_PASTE (56) for inter-app text sharing.
  • Notifications: SYS_NOTIFY (57) — toast-style notifications with color accent bars.
  • File dialogs: SYS_FILE_OPEN_DLG (58) and SYS_FILE_SAVE_DLG (59).
  • Date setting: SYS_SETDATE (49) — write to RTC from user programs.
  • Widget toolkit: 7 sub-functions (button, checkbox, progress bar, textbox, listbox, label, rectangle outline) for GUI_DRAW_BUTTON through GUI_DRAW_RECT (sub-functions 20–26).

Kernel — Screensaver System (kernel/screensaver.inc)

  • 5 screensaver modes: Starfield (64 parallax stars), Matrix (cascading green columns), Pipes (6 colored growing pipes), Bouncing Logo, Plasma (color-cycling plasma effect).
  • Activates after 5 minutes idle. scrsaver shell command to cycle/set mode.

Kernel — Bug Fixes

  • VBE font restore: Save/restore 8 KB VGA plane 2 font data before/after BGA mode switches. Fixes corrupted text mode characters after exiting Burrows desktop.
  • 3D button rendering: gui_bb_button_3d left-highlight vline clobbered EDX (button height) with the white color value. This caused 3 spurious dark vertical lines from each window's title bar buttons to the bottom of the screen. Fixed by preserving EDX across the vline call.
  • HBFS directory caching: Added cache-tag check in hbfs_load_root_dir to avoid redundant disk reads during PATH searches.
  • HBFS timestamps: Files now store RTC-based create/modify timestamps in DOS-compatible packed format.
  • HBFS symbolic links: File type 5 (FTYPE_LINK) with ln -s shell command and stat resolution.

Shell — New Commands

  • stat: Display file metadata (type, size, blocks, timestamps, link target).
  • fsck: Filesystem consistency check (bitmap vs. directory cross-validation).
  • whoami: Print current user name.
  • ln: Create symbolic links (ln -s target linkname).
  • scrsaver: Cycle or set screensaver mode.
  • mouse: Show mouse position and button state.
  • Total: 58 unique commands + 6 aliases = 64 dispatched names.

Programs — 61 New Programs (79 → 140)

New games: blackjack, breakout, chess, connect4, freecell, kingdom, mastermind, neurovault, outbreak, pong, puzzle15, raycaster, rogue, simon, solitaire, starfield.

New utilities: asm (in-OS assembler), banner, base64, basename, bcalc, bedit, bforager, bhive, bnotes, bpaint, bplayer, bsettings, bsheet, bsysmon, bterm, bview, cmp, csv, cut, debug, df, diff, dirname, du, expr, factor, find, forth, free, grep, hexdump, id, lolcat, mandel, nl, od, paste, periodic, perl (interpreter), pipes, ps, sed, seq, sort, strings, sysinfo, tac, tcc (C compiler).

Programs — Perl Interpreter & Samples

  • perl: In-OS Perl interpreter supporting variables, arrays, hashes, control flow, string operations, and built-in functions.
  • 6 Perl sample scripts: hello.pl, factorial.pl, fizzbuzz.pl, guess.pl, arrays.pl, strings.pl.

Syscall Summary

20 new syscalls added (48 → 68 total, numbered 0–67):

Range Syscalls
49 SYS_SETDATE
50–52 SYS_AUDIO_PLAY, SYS_AUDIO_STOP, SYS_AUDIO_STATUS
53–54 SYS_KILL, SYS_GETPID
55–56 SYS_CLIP_COPY, SYS_CLIP_PASTE
57 SYS_NOTIFY
58–59 SYS_FILE_OPEN_DLG, SYS_FILE_SAVE_DLG
60–63 SYS_PIPE_CREATE, SYS_PIPE_WRITE, SYS_PIPE_READ, SYS_PIPE_CLOSE
64–65 SYS_SHMGET, SYS_SHMADDR
66–67 SYS_PROCLIST, SYS_MEMINFO

Documentation

  • All 7 documentation files verified and updated against actual kernel code.
  • Fixed outdated statistics across README, USER_GUIDE, INSTALL, TUTORIAL, TECHNICAL_REFERENCE.

ISO Distribution

  • Bootable ISO: make iso produces an El Torito no-emulation ISO with full disk image, all 7 docs, README, LICENSE, and CHANGELOG.
  • Lite ISO: make iso-lite truncates the 2 GB disk image to 64 MB (~65 MiB ISO vs ~2.1 GiB full) — all HBFS data preserved.
  • ISO verification: make iso-verify validates the El Torito boot record and boot-load-size.
  • ISO launcher: run_iso.sh extracts and boots the ISO with colored output and ASCII banner.
  • Build script: build_iso.sh rewritten with ANSI-colored status output, pre/post build stats, and SHA256 checksums.
  • Supports 4 ISO-creation backends: xorriso, genisoimage, mkisofs, hdiutil.

Build Stats

  • Disk image: 169 files, 710 blocks across 4 subdirectories
  • Kernel: ~28,800 lines of x86 assembly (22 include files)
  • Kernel binary: ~550 KB
  • Tests: 1,160 (45 build + 1,115 HBFS integrity)
  • Syscalls: 68 (0–67)
  • Programs: 140 assembly + 11 C samples + 6 Perl samples

v2.1.0 - Full TCP/IP Networking Stack

Kernel — TCP/IP Networking (kernel/net.inc, ~3,800 lines)

The former RTL8139 networking stub has been replaced with a complete, from-scratch TCP/IP stack:

  • RTL8139 NIC driver: PCI auto-detect (bus/device/function scan), software reset with timeout, interrupt-driven RX/TX (ISR handles ROK, TOK, RER, TER, LinkChg), 8 KB RX ring buffer with wrap-around, 4 TX descriptors with round-robin rotation.
  • Ethernet II: Frame construction and parsing with proper EtherType dispatch (0x0800 IPv4, 0x0806 ARP).
  • ARP: Request/reply handling, 16-entry ARP cache with lookup and expiry, gratuitous ARP on interface configuration.
  • IPv4: Header construction with checksum, packet reception and protocol dispatch (ICMP=1, UDP=17, TCP=6).
  • ICMP: Echo request/reply (ping) with sequence numbering and round-trip time calculation.
  • UDP: Connectionless send/receive with port matching, used for DHCP and DNS.
  • TCP: Full state machine — SYN → SYN-ACK → ESTABLISHED → data transfer → FIN/FIN-ACK → CLOSED. Sequence/acknowledgment number tracking, 1460-byte MSS, retransmission, connection timeout.
  • DHCP client: Complete 4-phase negotiation (DISCOVER → OFFER → REQUEST → ACK) with option parsing for subnet mask, gateway, DNS server, and lease time.
  • DNS resolver: UDP-based query construction and response parsing with answer section extraction.

Kernel — Socket API (10 new syscalls)

Syscall Number Description
SYS_SOCKET 39 Create a TCP or UDP socket
SYS_CONNECT 40 Connect a TCP socket to a remote host:port
SYS_SEND 41 Send data on a connected socket
SYS_RECV 42 Receive data from a connected socket
SYS_BIND 43 Bind a socket to a local port
SYS_LISTEN 44 Mark a socket as listening for connections
SYS_ACCEPT 45 Accept an incoming TCP connection
SYS_DNS 46 Resolve a hostname to an IPv4 address
SYS_SOCKCLOSE 47 Close a socket and free resources
SYS_PING 48 Send an ICMP echo request and wait for reply

Kernel — ISR TX Re-entrance Fix

  • Problem: TCP acknowledgments and DHCP responses were sent from within the RTL8139 interrupt handler (ISR), which could corrupt in-flight TX descriptors and cause packet loss or hangs.
  • Solution: Added SOCK_PENDING field (offset 48) to the socket structure. The ISR stores pending flags (ACK, SYN-ACK, FIN-ACK) instead of calling tcp_send_flags directly. Polling loops in sys_connect, sys_recv, sys_send, sys_accept, and sys_sockclose call tcp_flush_pending to drain deferred transmissions outside interrupt context.
  • Impact: Fixed DHCP timeout failures and TCP connection stalls.

Kernel — Bug Fixes

  • sys_recv return path: Changed ret to iretd — the syscall returns via interrupt frame, not a near return. Missing iretd caused stack corruption and triple faults after receiving data.
  • DHCP buffer overflow: Reduced DHCP option copy length from 300 to 75 bytes (maximum valid DHCP option payload), preventing overwrite of adjacent kernel data.
  • DHCP race condition: Added dhcp_state flag to prevent processing duplicate OFFER/ACK packets from retriggered responses during the 4-phase handshake.

Shell — 5 New Networking Commands

  • dhcp: Run DHCP client to obtain IP, subnet mask, gateway, and DNS server.
  • ping <host>: Send ICMP echo request and display RTT.
  • arp: Display the ARP cache (IP → MAC mappings).
  • ifconfig: Show network interface configuration (IP, MAC, gateway, DNS).
  • net: Display NIC status, PCI location, I/O base, and MAC address.

Programs — 7 New Internet Clients + Network Library

  • forager — HTTP/1.0 web browser. Connects to port 80, sends GET request, displays response body. Tested end-to-end with forager example.com in QEMU.
  • ping — Standalone ICMP ping utility with configurable count, TTL display, and RTT statistics.
  • telnet — Interactive Telnet client with raw TCP socket communication and escape sequences.
  • ftp — FTP client with passive mode, directory listing, file get/put, and cd/ls commands.
  • gopher — Gopher protocol browser (port 70) with selector navigation.
  • mail — SMTP mail client for composing and sending email via port 25.
  • news — NNTP news reader for browsing Usenet newsgroups.
  • programs/lib/net.inc: User-space networking library with socket wrappers, DNS helper, HTTP request builder, and line-buffered receive.

Build Stats

  • Disk image: 96 files across 4 subdirectories
  • Kernel: ~20,000 lines of x86 assembly (19 include files)
  • Kernel binary: ~399 KB
  • Tests: 709 (175 build + 534 HBFS integrity)
  • Syscalls: 48 (0–48)
  • Programs: 79 assembly + 11 C samples

v2.0.0 - Paging, Preemptive Multitasking, Mouse, Burrows Desktop & 10 New Programs

Kernel — Virtual Memory

  • Paging (kernel/paging.inc): Identity-maps the first 128 MB via 32 page tables (page directory at 0x380000, page tables at 0x381000). All pages marked present, writable, and user-accessible. paging_map_page utility for dynamic page mapping. Page-fault handler (INT 14) prints faulting address, EIP, and error code, then recovers to the shell.

Kernel — Preemptive Multitasking

  • Preemptive scheduler: The PIT timer handler (IRQ0) now preempts ring-3 tasks every 100 ms (10-tick quantum at 100 Hz). Checks interrupted code's CPL via the CS RPL bits on the interrupt stack frame — kernel code is never preempted. Round-robin scan for next READY task with TCB ESP save/restore and TSS ESP0 update. Cooperative SYS_YIELD still works alongside preemptive switching.

Kernel — PS/2 Mouse Driver

  • Mouse driver (kernel/mouse.inc): Initializes the PS/2 auxiliary port via the 8042 controller (enable aux device, read/write command byte, set defaults, enable data reporting). IRQ12 handler collects 3-byte packets (flags, delta-X, delta-Y) with packet sync validation (bit 3 check). Tracks mouse_x (0–79), mouse_y (0–24), and mouse_buttons (left/right/middle). PS/2 Y-axis inversion for screen coordinates.
  • SYS_MOUSE (syscall 36): Returns mouse position and button state (EAX=x, EBX=y, ECX=buttons).
  • mouse shell command: Displays current mouse position and button state.

Kernel — Burrows Desktop Environment

  • VBE/BGA driver (kernel/vbe.inc): Detects Bochs VBE adapter via I/O ports (IDs 0xB0C0–0xB0C5). Sets linear framebuffer modes from protected mode (no real-mode INT 10h). Default 640×480×32 mode. LFB identity-mapped (8 MB) via paging_map_page. Full VGA mode 3 restore with CRTC/GC/AC register reprogramming.
  • Drawing primitives: vbe_putpixel, vbe_fill_rect, vbe_clear.
  • SYS_FRAMEBUF (syscall 37): Sub-functions for get info (0), set mode (1), and restore text mode (2).
  • gui shell command: Enters the Burrows desktop at 640×480 with colour bars and mouse cursor tracking. Press any key to return to text mode.

Shell — Wildcard Expansion

  • Global glob preprocessing (shell_expand_globs): Before command dispatch, all arguments containing * or ? are expanded against the current directory listing. Matching filenames replace the glob pattern in the command line. Unmatched globs are passed through literally (POSIX behavior). This makes wildcards work for all commands (e.g., cat *.txt, wc *.c), not just del and copy.

Programs — 10 New Showcase Programs

  • top — Live process/task monitor showing scheduler state, memory usage, and uptime
  • rogue — ASCII roguelike dungeon crawler with FOV, inventory, combat, and multiple dungeon levels
  • starfield — Animated 3D starfield simulation with parallax depth effect
  • matrix — Matrix-style falling green character rain animation
  • weather — Simulated weather station with multi-day forecast display
  • periodic — Interactive periodic table browser with element details
  • forth — FORTH language interpreter with stack operations, arithmetic, and word definitions
  • chess — Two-player chess with move validation, check detection, and Unicode-style pieces
  • clock — Analog ASCII clock with sin/cos lookup tables, hour/minute/second hands, and digital display
  • asm — Interactive x86 assembler REPL that shows machine code bytes for ~25 instruction types

Build Stats

  • Disk image: 83 files, 248 blocks used
  • Kernel: ~13,800 lines of x86 assembly (19 include files)
  • Tests: 618 (84 build + 534 HBFS integrity)
  • Syscalls: 38 (0–37)
  • Programs: 66 assembly + 11 C samples

v1.16 - Batch Scripting, Cooperative Multitasking & Networking

Shell Enhancements

  • Batch scripting directives: :LABEL, goto LABEL, if [not] errorlevel N cmd, rem comments, and @cmd (silent execution). Batch scripts now support conditional branching and flow control.
  • Background job detection: Trailing & on a command line is detected and stripped with a "not yet supported" message; the command runs in the foreground. Prepares the shell syntax for future background job support.
  • net command: Displays NIC status, PCI location, I/O base address, and MAC address.
  • ls -l timestamps: Long directory listing now shows a Modified column with time since boot in HHH:MM:SS format, read from the HBFS DIRENT_MODIFIED field.

Kernel / Subsystems

  • SYS_STDIN_READ (syscall 34): Programs can read piped stdin data from the shell's redirection buffer. Returns byte count in EAX, or -1 if no stdin is available.
  • SYS_YIELD (syscall 35): Cooperative yield syscall for the new scheduler. Saves the current task's ring-3 context and switches to the next ready task via round-robin.
  • Cooperative scheduler (kernel/sched.inc): Task Control Block (TCB) array supporting up to 4 concurrent tasks. Per-task kernel stacks allocated from PMM. Round-robin sys_yield with proper TSS ESP0 updates for ring transitions.
  • RTL8139 networking stub (kernel/net.inc): PCI bus 0 scan for RTL8139 NIC, software reset, RX/TX buffer allocation via PMM, MAC address read, and frame transmit function. Foundation for future TCP/IP support.

Programs — Stdin Pipe Support

  • sort, tr, grep, sed, cut: Now accept piped stdin when no filename argument is given (e.g., cat file | sort).
  • tee: Redesigned to support tee OUTFILE (reads stdin) in addition to the legacy tee INFILE OUTFILE mode.

Tests & CI

  • Portable test script: tests/test_build.sh now works on both macOS and Linux. Replaced GNU-specific stat -c with a wc -c based file_sz() helper, and grep -oP with grep -E -o pipelines.
  • Syscall consistency: Test now verifies all 36 syscalls (was 34).

Build Stats

  • Disk image: 73 files, 233 blocks used
  • Kernel: ~12,300 lines of x86 assembly (16 include files)
  • Tests: 45 build + 534 HBFS integrity
  • Syscalls: 36 (0–35)

v1.15 - Kernel Hardening & Interrupt Safety

Kernel Bug Fixes

  • build_cwd_path buffer overflow: Path construction wrote to a 256-byte buffer but max path depth (16 levels × 253 chars) could reach ~4 KB. Enlarged path_search_buf to 4096 bytes and added bounds checking with guaranteed null termination on truncation.
  • copy_word unbounded write: Shell word extraction had no destination size limit. Added bounded copy_word_n variant (ECX = max bytes, always null-terminates). Migrated cmd_find_file, cmd_append_file, and cmd_mkdir to use the bounded version.
  • Ctrl+C redirection state leak: Pressing Ctrl+C during a redirected command (e.g., prog > file) left stdout_redir_active and related flags set, corrupting subsequent output. The Ctrl+C handler now calls shell_redir_reset to clear all redirection state before returning to the shell prompt.
  • Interrupt-unsafe stdout redirection: A keyboard interrupt during vga_putchar's redirection check could corrupt the redirect buffer or length counter. Wrapped the redirection capture section with cli/sti to make the test-and-write atomic.
  • Interrupt-unsafe directory state: cd path traversal modified dir_depth, current_dir_lba, current_dir_sects, and current_dir_name without interrupt protection. A Ctrl+C mid-update could leave the directory stack inconsistent. Added cli/sti around state mutations in both cd_enter_subdir and cd_pop_stack.

Library Bug Fixes

  • io_file_write register mapping: Register remapping clobbered ECX (size) before copying it to EDX. The syscall received the buffer address as the size argument, causing writes to produce corrupted or zero-length files. Fixed register assignment order to preserve all parameters correctly.

Build System

  • Makefile lib dependency tracking: Program build rule now depends on $(wildcard programs/lib/*.inc) in addition to syscalls.inc, so changes to any library file trigger program rebuilds.

Tests

  • NOBITS warning regression test: New test in test_build.sh scans all .lst files for "nobits" warnings, catching section .bss ordering bugs (like the v1.14 math.inc issue).
  • File content integrity test: New test in test_hbfs.py reads known program binaries from the disk image and compares them byte-for-byte with the local .bin files, catching populate.py data corruption.

Documentation

  • API_REFERENCE.md: Added error handling patterns table documenting which functions use EAX=-1, EAX=0/null, or carry flag for error signaling.

v1.14 - Test Suite Expansion & Shell Hardening

Bug Fixes

  • Alias expansion infinite loop: If an alias expanded to a command starting with its own name (or circular aliases like A→B, B→A), the shell would loop forever. Added alias_expanding guard flag that limits alias expansion to one level per command line, matching standard shell behavior:contentReference[oaicite:0]{index=0}. The flag is reset at each new prompt.
  • sys_readdir unbounded filename copy: The SYS_READDIR syscall copied filenames to the user buffer without length checking, risking buffer overflow if the caller provided a small buffer. Now capped at HBFS_MAX_FILENAME (252) bytes with forced null termination.

Test Suite

  • Build tests expanded (31 → 44): New checks include:
    • All 55 program binaries built successfully (was only 12 spot-checked)
    • No program exceeds 1MB (PROGRAM_MAX_SIZE)
    • 9 HBFS constant consistency checks between kernel.asm and populate.py
    • All 34 syscall numbers verified consistent between kernel.asm and programs/syscalls.inc
    • Kernel binary entry point validation
  • HBFS integrity tests expanded (40 → 534): New checks include:
    • Full subdirectory traversal — all 4 subdirectories validated with child file entry checks
    • Program binary header validation — all 55 executables checked for valid x86 opcode at entry
    • Global block allocation overlap check across all directories (root + subdirectories)
    • Bitmap-vs-file block count cross-verification
    • Stray bitmap bit detection beyond allocated range
    • File census — total files across all directories verified (72 files)

Build Stats

  • Disk image: 72 files, 229 blocks used
  • Kernel: ~10,600 lines of x86 assembly
  • Tests: 578 (44 build + 534 HBFS integrity)

v1.13 - Standard PATH-Based Program Search

Breaking Change

  • Removed global directory search: File operations (cat, size, rm, rename, stat, fd_open, etc.) now only search the current working directory. Previously, any file could be accessed from any directory without a path — the kernel would silently scan root and every subdirectory. This was non-standard.. Users must now either cd into the correct directory or use an explicit path (e.g., cat /docs/readme.txt).

Shell / Exec

  • PATH-based program execution: cmd_exec_program still uses the PATH environment variable (default PATH=/bin:/games) to search for executables not found in the current directory. This is the only remaining multi-directory search and works like Unix $PATH.
  • which command: Continues to check builtins first, then CWD, then PATH directories — unchanged.

Bugfix

  • env_get_var fix: env_get returns the value pointer in EAX (pushad frame offset 28), but env_get_var was checking EDI (unchanged after popad) instead of EAX — so it always reported "not found". Fixed to use test eax, eax. This was a latent bug masked by the old global directory search; with global search removed, PATH-based exec depended on env_get_var working correctly.

Serial I/O Hardening

  • Hardware probe: serial_init now tests the UART scratch register before configuring COM1. If no serial hardware is detected, serial_present is set to 0 and all serial I/O becomes a safe no-op.
  • Non-blocking serial_getchar: Changed from an infinite busy-wait to a non-blocking poll. Returns 0xFF immediately when no data is available. SYS_SERIAL_IN (syscall 33) now correctly returns -1 when the receive buffer is empty, matching the documented ABI.
  • Guard on serial_putchar: Skips output when serial_present is 0, preventing hangs on systems without a UART.
  • serial test utility (/bin/serial): New program for interactive bidirectional serial testing. serial send <text> sends a line; bare serial enters an interactive terminal (green = outgoing, cyan = incoming, Escape to quit).
  • make run-serial: New Makefile target that launches QEMU with serial on TCP port 4555 (nc localhost 4555 to connect).
  • Documentation: readme.txt and notes.txt updated with serial usage instructions, QEMU connection examples, and use cases (debug logging, remote shell, file transfer, automated testing, data export).

Internal

  • hbfs_find_file_global: Simplified from a full recursive directory scan to a single CWD lookup (hbfs_load_root_dir + hbfs_find_file). The .gff_moved flag is always 0 now (kept for ABI compatibility with callers that check it).
  • hbfs_read_file: Removed the .not_found fallback that scanned all directories. Path-qualified filenames (/dir/file) still work via the path resolution code path.
  • Kernel binary: ~470 bytes smaller from removed global search code.

v1.12 - Compiler Fixes, Kernel Hardening & Modular Split

TCC Compiler Fixes

  • Expression precedence: Replaced flat single-level expression parser with a 7-level precedence-climbing parser (|| → && → ==/!= → </>/<=/>= → +/- → *///% → unary). Operators now bind correctly: 2 + 3 * 4 evaluates to 14, not 20.
  • String literal addressing: Rewrote string handling to use a fixup table. store_string returns a string index; emit_string_data emits string bytes at the end of the output and patches all fixup locations with correct runtime addresses. Fixes printf/string-literal crashes.

Build System (v1.12)

  • Auto kernel size: stage2.asm no longer has a hardcoded KERNEL_SECTORS equ 384. The Makefile generates kernel_sectors.inc from the actual kernel.bin size (ceil(size / 512)), so the stage 2 loader always loads exactly the right amount.
  • Kernel include tracking: $(KERNEL_BIN) now depends on $(wildcard kernel/*.inc), so touching any include file triggers a rebuild.
  • Regression test suite: New make check target runs 71 automated tests:
    • tests/test_build.sh — binary size guards (boot ≤ 512, stage2 ≤ 16 KB, kernel < 512 KB), MBR signature, superblock magic, bitmap and root directory sanity, program binary existence, TCC binary checks.
    • tests/test_hbfs.py — deep HBFS integrity: superblock field validation, bitmap-vs-directory consistency, per-file block range and allocation overlap checks.

Kernel Hardening

  • ATA retry wrappers: ata_read_sectors and ata_write_sectors now retry up to 3 times with an ATA soft reset (SRST via control register 0x3F6) between attempts. All existing callers (HBFS, shell commands, syscalls) automatically benefit. The raw single-attempt functions are still available as ata_read_sectors_raw / ata_write_sectors_raw.
  • HBFS error propagation: hbfs_load_root_dir, hbfs_load_bitmap, and hbfs_save_root_dir now return CF (carry flag) on I/O failure with descriptive error messages.

Kernel Modular Split

  • 13 include files: kernel.asm is now a 300-line master file (constants, entry point, %include directives). The ~10,300 lines of subsystem code are split into:
    • kernel/vga.inc — VGA text mode driver
    • kernel/pic.inc — PIC initialization
    • kernel/idt.inc — IDT setup
    • kernel/isr.inc — ISR/IRQ handlers
    • kernel/pit.inc — PIT timer + keyboard driver
    • kernel/pmm.inc — physical memory manager
    • kernel/ata.inc — ATA PIO driver + retry wrappers
    • kernel/hbfs.inc — HBFS filesystem
    • kernel/filesearch.inc — global file search
    • kernel/syscall.inc — syscall handler
    • kernel/shell.inc — command shell (~4,200 lines)
    • kernel/util.inc — utilities, serial, RTC, speaker, TSS, ELF loader, FD table, env vars, subdir support, new syscalls/commands, tab completion
    • kernel/data.inc — string data, scancode tables, IDT descriptor, BSS
  • Binary output is byte-identical to the monolithic version.

Build Stats (v1.12)

  • Disk image: 48 files, 188 blocks used
  • Kernel: ~10,600 lines of x86 assembly (split across 14 files)
  • Tests: 71 (31 build + 40 HBFS integrity)

v1.10 - Robustness & Filesystem Integrity Enhancements

Enhancements

  • df total file count: The df command now counts files across all directories (root + subdirectories), not just the current directory. Reports "N files in M directories" instead of showing a count for just the CWD.
  • Superblock free_blocks tracking: hbfs_alloc_blocks and hbfs_free_blocks now update the superblock's free_blocks counter (offset 12) after every allocation/deallocation, keeping the on-disk superblock consistent with the bitmap.
  • Nested batch execution guard: cmd_exec_batch now detects re-entrant calls (a batch command inside a .bat script) and rejects them with an error message instead of silently corrupting the shared batch_script_buf / batch_line_buf buffers.

Build Stats (v1.10)

  • Disk image: 48 files, 188 blocks used
  • Kernel: ~10,000 lines of x86 assembly

v1.9 - Code Review Bug Fixes & Enhancements

Critical Bug Fixes

  • .save_type overflow (hbfs_create_file): The file type parameter was stored via mov [.save_type], edx (32-bit write) into a 1-byte db 0 variable, corrupting the first 3 bytes of hbfs_delete_file_entry (overwriting the pushad opcode). Fixed by changing to dd 0.
  • cmd_cd silent failure: The cd command checked [esp + 28] (stale pushad-saved EAX) instead of the actual EAX register returned by cmd_cd_internal. This meant cd to a nonexistent directory never showed an error message. Fixed to cmp eax, -1.
  • fd_close cross-directory bug: When a file opened via hbfs_find_file_global from another directory was closed after writes, fd_close only searched the current directory for the entry to persist the updated file size — silently dropping the update. Fixed by recording the directory LBA/sects in the fd table entry at open time (offsets 20-27), then switching to that directory during close.
  • sys_exec_call always returned 0: The SYS_EXEC syscall returned xor eax, eax even when cmd_exec_program failed (CF set). Programs calling SYS_EXEC couldn't detect failure. Now returns -1 on failure.

Enhancements (v1.9)

  • cat -n line numbering: Replaced manual 4-digit space padding with vga_print_dec_width for cleaner, more maintainable code.
  • str_has_wildcards / str_has_asterisk: Now preserve ESI (push/pop) to prevent subtle caller bugs.
  • ls -l alignment: Right-aligned file sizes in 9-character field using vga_print_dec_width.
  • SYS_FWRITE file type: ESI parameter now specifies file type (FTYPE_TEXT..FTYPE_BATCH); TCC passes FTYPE_EXEC so compiled programs show as executables.
  • Shutdown message: Styled with COLOR_HEADER separator bar; message printed before ACPI shutdown to prevent cutoff.

Build Stats (v1.9)

  • Disk image: 48 files, 188 blocks used
  • Kernel: ~9,900 lines of x86 assembly

v1.8 - Global File Search (Directory-Transparent Operations)

hbfs_find_file_global

  • New core function: hbfs_find_file_global searches for a file across all directories — current dir first, then root, then every subdirectory. Returns with CWD pointing to the directory containing the file, so save/delete/rename operations target the correct location.
  • GFF-private CWD save/restore: Dedicated gff_save_cwd/gff_restore_cwd with separate BSS slots (gff_cwd_lba, gff_cwd_sects, gff_cwd_depth, gff_cwd_name, gff_cwd_stack) — avoids conflicts with file_save_cwd and path_save_cwd used by other subsystems.
  • .gff_moved flag: Callers check this to know whether CWD was changed, and restore it after the operation completes.

Commands Updated

  • rm / del: Fixed CPU exception bug — now uses hbfs_find_file_global + restores CWD after delete. Files can be deleted from any directory regardless of where the user is.
  • ren / rename: Uses global search for exact renames; saves directory after rename, then restores CWD.
  • size: Uses global search to display file info from any directory.
  • SYS_DELETE (syscall 9): Programs can now delete files in any directory.
  • SYS_STAT (syscall 11): Programs can now stat files in any directory.
  • fd_open: File descriptors can now open files in any directory.

Build Stats (v1.8)

  • Disk image: 48 files, 188 blocks used
  • Kernel: ~9830 lines of x86 assembly (~166KB)

v1.7 - Path-Based File Access

Path Resolution in hbfs_read_file

  • Full path support: All file operations (cat, batch, run, diff, head, tail, etc.) now accept absolute and relative paths — e.g., cat /docs/readme, run /bin/hello, diff /docs/readme /docs/notes
  • Automatic path splitting: hbfs_read_file scans filenames for /; if found, splits into directory part and basename, cd's into the directory, reads the file, then restores the user's original working directory
  • file_save_cwd / file_restore_cwd: Separate CWD save/restore functions using dedicated BSS variables (file_save_lba, file_save_sects, file_save_depth, file_save_name, file_save_stack), avoiding conflicts with path_save_cwd used by the PATH search
  • Relative paths: Supports ../bin/hello, games/snake, ./readme — resolves via cmd_cd_internal which handles ., .., absolute, and multi-component paths
  • Zero call-site changes: All 19 callers of hbfs_read_file gain path support automatically

Build Stats (v1.7)

  • Disk image: 48 files, 188 blocks used
  • Kernel: ~9510 lines of x86 assembly (165KB)

v1.6 - Directory Organization & PATH Search

Filesystem Restructuring

  • Subdirectory support in populate.py: Rewrote image builder with FSImage class supporting create_subdir() and add_file(directory=...) methods
  • Organized virtual drive into 4 subdirectories:
    • /bin — 22 utility programs (hello, edit, mandel, tcc, sort, grep, wc, etc.)
    • /games — 10 game programs (2048, galaga, guess, life, maze, mine, piano, snake, sokoban, tetris)
    • /samples — 10 C source files (hello.c, fib.c, calc.c, matrix.c, wumpus.c, etc.)
    • /docs — 5 text files (readme, license, notes, todo, poem)

PATH-Based Program Search

  • Working PATH mechanism: Kernel searches colon-separated PATH directories when a program isn't found in the current directory
  • Default PATH: Set to /bin:/games — programs in these directories run from anywhere
  • set PATH command: Users can customize PATH (e.g., set PATH /bin:/games:/samples)
  • path_save_cwd / path_restore_cwd: Utility functions to save and restore full directory state (LBA, sectors, depth, name, dir_stack) during PATH traversal
  • cd-based search: PATH search cd's into each directory, searches there, reads file data directly from directory entry, then restores the user's original working directory

Updated Commands

  • which: Now searches PATH directories; shows full path (e.g., hello is /bin/hello (external))
  • help: Updated to mention PATH search and configuration instructions

Bug Fixes (v1.6)

  • Critical PATH fallthrough fix: .path_not_found was falling through into .found_program — now correctly jumps to .not_found
  • NASM optimization oscillation: Added -O0 flag to kernel build to prevent label oscillation errors during assembly

Build Stats (v1.6)

  • Disk image: 48 files, 188 blocks used (4 subdirectories + files)
  • Kernel: ~9440 lines of x86 assembly

v1.5 - Command & Program Expansion

New Internal Commands (11)

  • diff: Side-by-side file comparison with colored output (< red, > green)
  • uniq: Remove adjacent duplicate lines; flags: -c (count prefix), -d (duplicates only)
  • rev: Reverse each line of a file character-by-character
  • tac: Print file lines in reverse order (last line first)
  • alias: Define, list, and show shell command aliases (16-slot table)
  • history: Display numbered shell command history from history buffer
  • which: Locate a command — shows if built-in or finds external program on disk
  • sleep: Pause for N seconds (100 ticks/sec timer), supports Ctrl+C abort
  • color: Set foreground/background VGA color (hex values 0-F)
  • size: Show file size in bytes/blocks plus type (text/dir/exec/batch/unknown)
  • strings: Extract printable strings from a file (default ≥4 chars, configurable via flag)

Shell Enhancements

  • Alias expansion: Shell parser checks alias table before command dispatch; recursive expansion into alias_expand_buf

New Helper Functions

  • vga_newline: Convenience function wrapping mov al, 0x0A / call vga_putchar
  • str_compare: Compare two null-terminated strings at ESI/EDI, sets ZF on match

New External Programs (9 assembly)

  • life: Conway's Game of Life — 78×23 grid, glider/blinker/R-pentomino seeds
  • maze: Random maze generator + BFS solver — 39×21 DFS-carved maze with colored path
  • 2048: The 2048 sliding tile game — 4×4 board, arrow keys/WASD, scoring
  • piano: PC speaker piano — 15 notes (C4-D5), scale and Mary Had a Little Lamb demos
  • mandel: Mandelbrot set renderer — fixed-point 16.16 arithmetic, 78×23, color gradient
  • pager: File pager (like more) — 23-line pages, space/enter/q controls
  • sed: Stream editor — search and replace first occurrence per line
  • tr: Character translator — SET1→SET2 mapping via 256-byte translation table
  • csv: CSV file viewer — formatted columns, colored headers, pipe separators

New C Sample Programs (5)

  • hanoi.c: Tower of Hanoi solver (4 disks, iterative binary counter method)
  • bf.c: Brainfuck interpreter with hardcoded Hello World program
  • wumpus.c: Hunt the Wumpus — 8-room cave, move/shoot, hazards
  • matrix.c: Matrix rain effect — falling characters animation (40 columns × 20 rows)
  • calc.c: Integer calculator — multi-digit numbers with +, -, *, / operators

TCC Compiler Bug Fixes (3)

  • line_num reset: Line counter not reset between compilations — second compile reported wrong line numbers
  • add_global_var extra next_token: Global variable declarations consumed one too many tokens — broke subsequent parsing
  • Assignment expr_name clobbering: Assignment expression overwrote expr_name register — corrupted variable name lookup

Build Stats (v1.5)

  • Disk image: 48 files, 172 blocks used
  • Kernel: ~9250+ lines of x86 assembly

v1.4 - HBFS Filesystem Expansion

Bug Fixes (v1.4)

  • sys_free double-shift: pmm_free_page expects physical address but sys_free was converting to page number first, causing double shr 12 and freeing wrong pages — corrupted memory bitmap
  • cmd_copy_file stack corruption: Wildcard paths jumped to .src_not_found which did pop esi, but wildcard paths never pushed ESI — stack corruption on "no matches" case
  • env_get_var wrong register: Checked EDI == 0 instead of comparing EDI to saved copy; EDI was always non-zero (dest buffer pointer), so variable-not-found was never detected — broke PATH-based program search
  • hbfs_create_file overflow: .copy_name loop had no bounds check against HBFS_MAX_FILENAME (252); long filenames could overflow into metadata fields
  • df bitmap scan: Only scanned 512 of potentially 2000+ bitmap bytes — reported ~1/4 of actual disk usage on 64MB disks
  • hbfs_read_file stale buffer: Did not call hbfs_load_root_dir before hbfs_find_file, could search stale directory data
  • fd_close size persistence: File size updated via SYS_WRITE was only stored in the FD table — never written back to the directory entry on close; file appeared truncated after reopen
  • Batch script overwrite: cmd_exec_batch loaded scripts to PROGRAM_BASE where shell commands (cat, head, copy) also load data — commands would overwrite the batch script mid-execution
  • ATA LBA48 bits 24-31: Both ata_read_sectors and ata_write_sectors zeroed LBA byte 3 instead of sending bits 24-31 from EAX — limited disk access to 8GB (16M sectors) instead of the full 32-bit LBA range

New Syscalls

  • SYS_MKDIR (12): Create a subdirectory; EBX = name pointer, returns EAX = 0 success / -1 error
  • SYS_READDIR (13): Read directory entry by index; EBX = filename buffer, ECX = entry index, returns EAX = file type (-1 = end), ECX = file size

Documentation Fixes

  • Version text updated: v1.3 → v1.4, 28 → 227/56 files, 33 → 34 syscalls
  • Banner string updated: HB Lair v1.3 → v1.4
  • hbfs_find_file comment: "root directory" → "current directory"
  • HBFS_DIR_ENTRY_SIZE comment: corrected field sizes and order to match actual offsets
  • populate.py: Fixed root dir comment (2 → 16 blocks), readme.txt (34 syscalls), notes.txt (added SYS_SERIAL_IN), todo.txt (34 syscalls)
  • syscalls.inc: Documented SYS_MKDIR/SYS_READDIR as now implemented

Internal Changes (v1.4.1)

  • Extracted hbfs_mkdir shared function from cmd_mkdir — used by both shell command and SYS_MKDIR syscall
  • cmd_exec_batch uses 32KB batch_script_buf in BSS instead of PROGRAM_BASE
  • fd_close scans directory by start_block to persist file size for writable FDs
  • ata_read_sectors / ata_write_sectors send EAX[24:31] as LBA byte 3 in high phase

Major Changes

  • Root directory expanded: 2 blocks → 16 blocks (28 → 227 file entries per directory)
  • Subdirectories expanded: 1 block → 4 blocks per subdirectory (14 → 56 entries each)
  • Multi-level subdirectories: Full support for nested directories to 16 levels deep
  • Directory stack: Parent directory tracking via push/pop stack enables proper cd .. from any depth
  • Multi-component paths: cd a/b/c, cd ../sibling, cd /abs/path all work correctly
  • Full path display: Shell prompt, pwd, and SYS_GETCWD show complete path (e.g., /projects/src)

Disk Layout Changes

  • Kernel area increased from 192 to 384 sectors (96KB → 192KB) to accommodate larger BSS
  • Superblock moved from LBA 225 to LBA 417
  • Bitmap at LBA 418, Root directory at LBA 426-553, Data starts at LBA 554
  • Note: Existing disk images must be reformatted (incompatible layout change)

Internal Changes

  • New HBFS_SUBDIR_BLOCKS constant (4) controls subdirectory allocation size
  • New build_cwd_path utility builds full path string from directory stack
  • hbfs_format uses loop to zero all 16 root directory blocks
  • cmd_mkdir zeros all allocated blocks and stores correct block count
  • All 12 directory iteration loops auto-adapt via hbfs_get_max_entries
  • Added BSS: dir_depth (dword), dir_stack (16 × 264 bytes = 4,224 bytes)
  • hbfs_dir_buf expanded from 8KB to 64KB

v1.3 - Usability & Security Update

New Features

  • Command-line arguments: Programs receive arguments via SYS_GETARGS (syscall 32); shell parses program arg1 arg2 syntax
  • Ctrl+C hard-abort: Keyboard IRQ detects Ctrl+C while a program is running and immediately returns to shell (no program cooperation needed)
  • FD write implementation: SYS_WRITE via file descriptors now performs real block read-modify-write to disk instead of being a stub
  • Raw disk access restriction: SYS_DISK_READ (22) and SYS_DISK_WRITE (23) are denied to ring 3 user programs for security

New Programs

  • cal.asm: Calendar display showing current month with day-of-week calculation (Sakamoto's algorithm), highlights today
  • calc.asm: Interactive integer calculator with +, -, *, /, % operators, hex output, signed arithmetic

Enhancements (v1.3)

  • edit.asm: Now accepts filename from command line (edit myfile.txt) via SYS_GETARGS instead of always editing scratch.txt
  • Syscall count: 33 syscalls (added SYS_GETARGS = 32)
  • Version text: Updated to v1.3 with new feature descriptions

Documentation (v1.3)

  • INSTALL.md: Complete build and installation guide
  • USER_GUIDE.md: Comprehensive user manual with all commands
  • TECHNICAL_REFERENCE.md: Architecture, memory map, HBFS spec, driver details
  • PROGRAMMING_GUIDE.md: Tutorial on writing Mellivora OS programs
  • API_REFERENCE.md: Complete syscall API reference with examples

v1.2 - Major Feature Release

Bug Fixes (v1.2)

  • IRQ PIC2 EOI: Split irq_stub into PIC1-only and PIC2 variants; PIC2 IRQs now send EOI to both controllers
  • ATA sector overflow: LBA48 sector count now sends high byte (CH) instead of always 0
  • cmd_copy redundant find: Removed unnecessary second hbfs_find_file call; uses ECX from hbfs_read_file directly
  • guess.asm backspace: Backspace now does BS+space+BS for proper visual erase
  • CHANGELOG programs: Fixed v1.0 program list to match actual programs (banner, colors, guess, primes)
  • populate.py docs: Fixed stale notes.txt (root dir LBA 234-249, data LBA 250+), updated todo.txt/readme.txt

Architecture Enhancements

  • Ring 3 user mode: Programs now run in ring 3 with TSS (selector 0x28), user code/data segments (0x18/0x20)
  • ELF loader: Minimal ELF32 binary loader - parses ELF magic and loads PT_LOAD segments
  • Boot splash: Stage 2 displays blue title bar ("Mellivora OS - Booting...") during boot
  • Program return code: SYS_EXIT saves EBX as program exit code; shell reports non-zero codes

New Drivers

  • Serial console: COM1 at 115200 baud for debug output; serial_init/serial_putchar/serial_print
  • RTC clock: Read date/time from CMOS (ports 0x70/0x71) with BCD-to-binary conversion
  • PC speaker: PIT channel 2 beep via port 0x61; configurable frequency and duration

New Syscalls (6 new, total 30)

  • SYS_BEEP (24): Play tone on PC speaker (EBX=frequency, ECX=duration_ms)
  • SYS_DATE (25): Read RTC date/time into buffer
  • SYS_CHDIR (26): Change current directory
  • SYS_GETCWD (27): Get current working directory
  • SYS_SERIAL (28): Write string to serial port
  • SYS_GETENV (29): Get environment variable value
  • SYS_OPEN/READ/WRITE/CLOSE/SEEK (5-8,10): File descriptor operations implemented

New Shell Commands (13 new, total 34)

  • echo: Print text with $VAR environment variable expansion
  • wc FILE: Line, word, and byte count
  • find FILE PATTERN: Substring search with line numbers
  • append FILE TEXT: Append text to existing file
  • date: Display current date/time (YYYY-MM-DD HH:MM:SS)
  • beep: Play 1000Hz tone for 200ms
  • batch FILE: Execute shell commands from a script file
  • mkdir NAME: Create subdirectory entry
  • cd DIR: Change current directory
  • pwd: Print working directory
  • set NAME=VALUE: Set environment variable
  • unset NAME: Remove environment variable
  • Tab completion: Filename auto-completion in shell
  • Ctrl+C: Interrupt running program

New Subsystems

  • File descriptors: 8-slot FD table with open/read/write/close/seek operations
  • Environment variables: 16 variables, 128 bytes each, $VAR expansion in echo/batch
  • Subdirectories: Basic directory support with current_dir_lba tracking

New Programs (v1.2)

  • edit.asm: Full-screen text editor with cursor movement, insert/delete, Ctrl+S save, Ctrl+Q/ESC quit
  • tetris.asm: Classic Tetris with 7 tetrominoes, rotation, scoring, levels, next-piece preview

Code Quality

  • syscalls.inc: Shared include file with all 30 SYS_* constants and common print_dec routine
  • All 10 programs: Refactored to use %include "syscalls.inc", eliminated duplicated constants and print_dec
  • Makefile: Added .lst listing files, populate.py as dependency, syscalls.inc as program dependency
  • Named constants: DIRENT_* offsets for directory entry fields replace magic numbers

v1.1 - Comprehensive Review & Hardening

Bug Fixes (v1.1)

  • Multi-block filesystem: Files can now span multiple 4KB blocks. hbfs_alloc_blocks allocates N contiguous blocks, hbfs_create_file writes all sectors, hbfs_delete_file_entry frees all blocks.
  • parse_hex_byte: Fixed inverted carry flag semantics in hex byte parser (enter command).
  • Shift key bounds check: Added guard for scancodes < 0x20 before shift_table lookup to prevent out-of-bounds read.
  • Keyboard buffer overflow: Added buffer-full check before writing to ring buffer.
  • cmd_cat overflow: Clamp file read size to PROGRAM_MAX_SIZE - 1 to prevent null-terminator overflow.
  • ATA flush: Moved FLUSH CACHE command outside the write loop (was flushing after every sector).
  • Rename length check: Filename copy now checks against HBFS_MAX_FILENAME (252 chars).
  • Snake tail rendering: Save old tail position before shift_body loop, use saved coordinates for erase.
  • Sysinfo wasted division: Removed useless first div in uptime calculation (result was immediately overwritten).
  • Minesweeper stack overflow: Converted recursive 8-way flood_reveal (up to 800-deep recursion, ~80KB stack) to iterative algorithm with explicit stack array.

Robustness Improvements

  • IDT fully populated: All 256 IDT entries now filled with isr_default, preventing #GP on unexpected interrupts.
  • Exception handlers: Separate handlers for exceptions with/without error codes. Prints faulting EIP and error code, then recovers to shell (no more cli/hlt freeze).
  • Syscall register preservation: Syscall handlers now save/restore EBX, ECX, EDX, ESI, EDI. Only EAX is modified for return value.

New Syscalls (v1.1)

  • SYS_DELETE (9): Delete a file by name
  • SYS_STAT (11): Get file size and block count
  • SYS_MALLOC (19): Allocate 4KB-aligned physical memory pages
  • SYS_FREE (20): Free allocated memory pages
  • SYS_DISK_READ (22): Raw disk sector read
  • SYS_DISK_WRITE (23): Raw disk sector write

New Commands (v1.1)

  • df: Show HBFS filesystem usage (total/used/free blocks, file count)
  • more FILE: Page-by-page file viewer (23 lines per page, Space/Enter for next, q/ESC to quit)

New Features (v1.1)

  • Shell command history: Up/Down arrow keys recall previous commands (stores last 8 commands)
  • PMM multi-page allocation: pmm_alloc_pages allocates N contiguous physical pages
  • Bitmap load helper: hbfs_load_bitmap shared function for bitmap I/O

Documentation (v1.1)

  • Updated version text to v1.1 with new features
  • Fixed stale comments in populate.py (directory = 2 blocks/16 sectors, data starts at LBA 250)
  • Updated help text with df and more commands

v1.0 - Initial Release

  • 32-bit protected mode kernel with flat 4GB address space
  • HBFS filesystem with 4KB blocks and 28-entry root directory
  • ATA PIO disk driver with LBA48 support
  • VGA 80x25 text mode with 16 colors
  • PS/2 keyboard driver with shift key support
  • Physical memory manager with bitmap allocator
  • Heap allocator (simple bump allocator)
  • PIT timer at 100 Hz
  • 11 syscalls via INT 0x80
  • Shell with 14 built-in commands
  • 10 user programs (hello, banner, colors, fibonacci, guess, primes, sysinfo, snake, mine, sokoban)