started setting up support for C code in the kernel

kernel/Cargo.toml

@@ -7,9 +7,12 @@ edition = "2021"
 limine = "0.3.1"
 lib_example = { path = "../lib_example" }
 
+[build-dependencies]
+cc = "1.2.14"
+
 [features]
 default = []
 
 [[bin]]
 name = "kernel"
-path = "src/main.rs"
+path = "src/main.rs"

kernel/build.rs

@@ -1,9 +1,14 @@
 use std::process::Command;
 use std::{env, path::Path};
+use cc;
 
 fn main() {
     // Tell cargo to rerun if these files change
     println!("cargo:rerun-if-changed=src");
     println!("cargo:rerun-if-changed=linker.ld");
     println!("cargo:rerun-if-changed=../config/limine.conf");
-}
+
+    cc::Build::new()
+        .file("src/main.c")
+        .compile("lib");
+}

kernel/src/main.c

@@ -0,0 +1,3 @@
+int add(int x, int y)  {
+    return x+y;
+}

kernel/src/main.rs

@@ -28,6 +28,11 @@ static _START_MARKER: RequestsStartMarker = RequestsStartMarker::new();
 #[link_section = ".requests_end_marker"]
 static _END_MARKER: RequestsEndMarker = RequestsEndMarker::new();
 
+
+extern "C" {
+    pub fn add(x: i32, y: i32) -> i32;
+}
+
 #[no_mangle]
 unsafe extern "C" fn kmain() -> ! {
     // All limine requests must also be referenced in a called function, otherwise they may be
@@ -35,6 +40,8 @@ unsafe extern "C" fn kmain() -> ! {
     assert!(BASE_REVISION.is_supported());
 
     lib_example::add_nums(1, 2);
+    add(1, 2);
+
 
     if let Some(framebuffer_response) = FRAMEBUFFER_REQUEST.get_response() {
         if let Some(framebuffer) = framebuffer_response.framebuffers().next() {