uefi.c3l - UEFI Definitions & Library for C3

A gnu-efi-like library enabling UEFI bootloader development in C3.

Installation

The library is incredibly easy to pull and use right away.

1. Change to your project's lib directory.
2. Clone this repository: git clone https://github.com/NotsoanoNimus/uefi.c3l.git.
3. Start developing with import uefi; where needed.

Most c3c projects will automatically source modules from their lib folders. If this is not the case, you can use the following c3c parameters to source the library: --lib uefi --libdir lib/

This will certainly be improved as the project becomes more mature.

Compiling EFI Binaries

I need to revisit this, but I have been successfully compiling my EFI test binaries with the following:

~$  c3c compile-only src/*.c3 --link-libc=no --no-entry \
        --target windows-x64 --lib uefi --libdir ./lib

~$  clang -target x86_64-unknown-windows -nostdlib -fno-stack-protector -mno-red-zone \
        -ffreestanding -fPIC -Wl,-entry:efi_main -Wl,-subsystem:efi_application \
        -fuse-ld=lld-link -mno-stack-arg-probe -v -o test.efi ./obj/windows-x64/*.obj

I'm pretty sure I'm switching up my compilation and linker arguments for this right now. 🤷 Again, to be improved as the project matures.

This snippet explicitly uses clang and lld-link in order to generate the EFI application. For me, it's a must; however, others may be more comfortable linking with another tool like gcc. It's all the same after c3c generates its objects.

Example Usage

The following example shows what a "Hello World" style EFI application might look like in C3. When it starts, it sets a baseline console color, clears the window, and attempts to enable the Graphics Output Protocol and draw a simple rectangle.

Some of these methods currently don't exist; this is more of a "finished product" presentation.

module hello_uefi;

import uefi;


fn EfiStatus efi_main(EfiHandle image_handle, SystemTable* system_table) @export("efi_main")
{
    pre_load::init(image_handle, system_table)!!;

    console::clear_to({YELLOW, RED});

    io::cprintn(@wstring("Enabling GOP mode..."), {GREEN, BLACK})!!;

    if (catch excuse = sys::enable_gop()) {
        io::cprintn(@wstring("ERROR: Failed to initialize Graphics Output Protocol."), {RED, BLACK})!!;
    } else {
        gop::draw_rect(
            {0, 0, 100, 200},
            {{0xff, 0x12, 0x34, 0x56}, {.a = 0xff, .r = 0xdd}} /* {r,g,b,a} */
        );
    }

    sys::@stall(s2us(3));   /* s2us == sec-to-microsec */
    sys::@reset(SHUTDOWN);
}

TODOs

In no particular order...

• Finish C3 standard library integration, to provide helpful constructs like String formatting and such.
• Implement all macro exports for System, Console, etc.
• Organize library imports such that uefi isn't just bulk-imported everywhere.
• Unit/Integration testing.
  • Not sure if this will require a mock UEFI environment, or if it will need to be on a function-by-function basis. We'll see.
• Graphics library support and support functions .
  • e.g. an optional BLT-based framebuffer lib.