FoundryOS/docs/Planning & To-Dos.md

[!todo] Testing

• setup custom test frameworks (Use CrystalOS-V2 as a reference)
  • write a sub-crate for tests
  • implement several unit tests on things that we are likely to break often
• setup Git CI/CD pipeline with testing
  • figure out how to run QEMU in the test environment
  • write a script to run tests
  • a release should only be published if all tests pass

[!todo] HAL (Hardware Abstraction Layer)

• use either traits or cfg attributes to support more than just x86_64
  • prefer writing cross platform code (I am aware I made the problem slightly worse by merging libk with the kernel sources)

[!todo] Allocator

• learn about several allocator designs and decide on the optimal one
• implementation
  • implement an allocate method
  • implement a deallocate method
  • set the global allocator
• testing
  • write unit tests
    • many allocations
    • large allocations
    • allocating more memory than is available
  • pass unit tests

[!todo] Threading

• implement thread switching functionality
  • switch stacks
• implement multi-threading
  • figure out how to turn on another core
• Scheduler
  • which task goes on which thread?
    • round robin / time slicing algorithm
  • switch tasks on a given core
    • push registers
    • switch stacks
    • ensure the scheduler knows where to find the stack for each thread
  • move a given task to a new core
  • differentiate between kernel threads and user threads
• create syscall to create a new thread

[!todo] Filesystem

• AHCI Implementation
  • figure out what hard drives are attached
  • read data
  • write data
• FAT32 Implementation
  • parse FAT header
  • figure out where files are / what files are what
  • parse file metadata / figure out type of file
  • reading the entirety of a file into memory
• (extension) ext2 Implementation
• Syscall API
  • provide a user program with file read / write access given a filename
    • translate a filename into a disk location of data & the size of the data
    • provide an interface to read from a file or write to a file

[!todo] APIC

• Enable APIC
  • Get apic location from MSR
  • Enable APIC bit flag
  • Disable Legacy PIC
  • Map physical APIC address to virtual memory

[!error] Page fault exception occurs when APIC is activated

• Setup Interrupt handlers to handle interrupts generated by the APIC
  • Timer Interrupts
  • Keyboard Interrupts

[!todo] Userspace (req: Threading, Filesystem)

• Load program into memory from disk
  • requires:
    • Program Loader
      • Parse ELF File
      • Load file into memory
    • Filesystem
    • Scheduler (to start and manage the process)
• Start a user process
  • switch stacks
  • jump to user code

[!todo] User Interface

• This will be a library so that programs in userspace can provide a user interface rather than relying on text commands from a basic terminal
• features required:
  • Rendering frames to a display buffer
    • requires: Frame rendering Syscall
  • I/O
    • syncio
      • keystrokes
    • asyncio
      • keystrokes
    • requires: I/O Syscalls
  • Window struct
    • stores it's size and location
    • handles rendering pixels to the screen
  • Widgets
    • textbox / label
    • single line text input
      • how do we capture keyboard inputs?
    • multiline text input
      • how do we capture keyboard inputs?
    • button
    • dialog
    • box widget
      • figure out how to nest other widgets inside it

pub struct Window {
  position;
  dimensions;
}

impl Window {
  fn display(&self, frame: &Frame) -> Result<(), RenderError>;
}

pub struct Frame<'a> {
  window: &'a Window,
  data: <"... a suitable type to store pixels">
}

impl<'a> Frame<'a> {
  pub fn display(&self) -> Result<(), RenderError> {
  	self.window.display(self)
  }
}

pub trait Widget {
	fn render(&self) -> Frame;
}