# **Essence** — An Operating System
Video demonstration as of October 2021, running on real hardware: (YouTube)
[](http://www.youtube.com/watch?v=aGxt-tQ5BtM "Essence — October ’21 Progress")
## Links
For discussion, join our Discord server: https://discord.gg/skeP9ZGDK8
Alternatively, visit the forums (not very active): https://essence.handmade.network/forums.
To support development, you can donate to my Patreon: https://www.patreon.com/nakst.
## Features
Kernel
* Filesystem independent cache manager.
* Memory manager with shared memory, memory-mapped files and multithreaded paging zeroing and working set balancing.
* Networking stack for TCP/IP.
* Scheduler with multiple priority levels and priority inversion.
* On-demand module loading.
* Virtual filesystem.
* Window manager.
* Audio mixer. (being rewritten)
* Optional POSIX subsystem, capable of running GCC and some Busybox tools.
Applications
* File Manager
* Text Editor
* IRC Client
* System Monitor
Ports
* Bochs
* GCC and Binutils
* FFmpeg
* Mesa (for software-rendered OpenGL)
* Musl
Drivers
* Power management: ACPI with ACPICA.
* Secondary storage: IDE, AHCI and NVMe.
* Graphics: BGA and SVGA.
* Read-write filesystems: EssenceFS.
* Read-only filesystems: Ext2, FAT, NTFS, ISO9660.
* Audio: HD Audio.
* NICs: 8254x.
* USB: XHCI, bulk storage devices, human interface devices.
Desktop
* Custom user interface library.
* Software vector renderer with complex animation support.
* Tabbed windows.
* Multi-lingual text rendering and layout with FreeType and Harfbuzz.
## Building
**Warning: This software is still in development. Expect bugs.**
### Linux
Download this project's source.
git clone --depth=1 https://gitlab.com/nakst/essence.git/
Start the build system.
./start.sh
Follow the on-screen instructions to build a cross compiler.
Once complete, you can test the operating system in an emulator.
* If you have Qemu and KVM installed, run `k` in the build system. **Recommended!**
* If you have Qemu installed, run `t2` in the build system.
* If you have VirtualBox installed, make a 128MB drive called `vbox.vdi` in the `bin` folder, attach it to a virtual machine called "Essence" (choose "Windows 7 64-bit" as the OS), and run `v` in the build system.
Run `build-port` in the build system to view a list of optional ports that can be built.
## Configuration
From within the build system, run the command `config` to open the configuration editor. Click an option to change its value, and then click the `Save` button. You changes are saved locally, and will not be uploaded by Git. Not all configurations are likely to work; if you don't know what you're doing, it's probably best to stick with the defaults.
### Keyboard layout
To set the default keyboard layout for use in the emulator to match your current one, run:
setxkbmap -query | grep layout | awk '{OFS=""; print "General.keyboard_layout=", $2}' >> bin/config.ini
## Generating the API header
If you want your project to target Essence, you need to generate the API header for your programming language of choice.
g++ -o bin/build_core util/build_core.c
bin/build_core headers <language> <path-to-output-file>
Currently supported languages are 'c' (also works for C++), 'zig' and 'odin'.
There is currently no documentation for the API; for examples of how to use the API, consult the standard applications in the `apps/` folder of the source tree. Minimal sample applications are placed in the `apps/samples` folder. By placing your application's `.ini` file in the `apps/` folder, it will be automatically built by the build system.
## TODO
**This list is incomplete!**
- Applications
- PDF viewer
- Media player
- Automator
- Web browser
- Desktop environment
- Alt-tab
- Saving application state on shut down
- Task list popup
- Add more settings, and organize them
- Print screen key
- Storing images in the clipboard
- Combined search and Lua REPL
- Clipboard viewer
- Improved color eyedropper
- File Manager
- Deleting files
- Improving thumbnail storage
- Property store
- Searching
- Search indexing
- Tagging; metadata
- Tracking source of files
- Localizing system folder names
- Previewing other file types
- Filtering
- Multi-rename
- Compressed archives
- Creating new files
- Automation
- Grouping
- GUI
- Drag and drop
- Keyboard navigation in menus
- Date/time entry
- Tokens in textbox
- Right-to-left layout
- Accessibility hooks (e.g. for a screen reader)
- Choice boxes
- Resizable scrollbars
- Asynchronously painted element
- Reorder lists
- Dialogs as separate windows
- File dialogs
- Textbox auto-complete
- Media display
- Progress bars
- Dockable UI
- Charts
- Gauges
- Password editor
- Scrollbar animations
- Scaling at the paint level (as well as layout)
- Simpler control of line clipping in `EsTextDisplay`
- Fast scroll
- Keeping items anchored when resizing
- Instance reference counting
- Text rendering
- Variable font support
- Fix custom font renderer
- Unicode bidirectional text algorithm
- Unicode vertical text layout algorithm
- OpenType features
- Grapheme splitter (for textbox)
- Fallback fonts for unsupported languages
- Consistent font size specification
- API
- Date/time
- 2D graphics
- Tweening
- Media decoding
- Debugging other processes
- `io_uring`-like file access
- String sorting; normalization; case conversion
- Shared code
- Better heap allocator
- Faster rendering routines
- Color spaces
- Theming
- Dark theme
- High contrast theme
- Bitmapped font
- Kernel
- Networking protocol implementation
- Networking hardware drivers
- Rewrite audio layer
- Asynchronous IO
- Better IPC messaging
- Double fault handler
- `x86_32` support
- ARM support
- Graphics card drivers
- Support for USB 3.0 devices
- OHCI/UHCI/EHCI drivers
- USB hub support
- Built-in debugger
- Decrease startup time
- Decrease memory usage
- Shared memory permissions
- Proper worker threads
- Read-write file systems: FAT, ext4, NTFS
- Documentation!