Create a basic LinkedListAllocator type

src/allocator.rs

@@ -9,6 +9,7 @@ use x86_64::{
 };
 
 pub mod bump;
+pub mod linked_list;
 
 pub const HEAP_START: usize = 0x_4444_4444_0000;
 pub const HEAP_SIZE: usize = 100 * 1024; // 100 KiB

src/allocator/linked_list.rs

@@ -0,0 +1,48 @@
+struct ListNode {
+    size: usize,
+    next: Option<&'static mut ListNode>,
+}
+
+impl ListNode {
+    const fn new(size: usize) -> Self {
+        ListNode {
+            size,
+            next: None,
+        }
+    }
+
+    fn start_addr(&self) -> usize {
+        self as *const Self as usize
+    }
+
+    fn end_addr(&self) -> usize {
+        self.start_addr() + self.size
+    }
+}
+
+pub struct LinkedListAllocator {
+    head: ListNode,
+}
+
+impl LinkedListAllocator {
+    /// Creates an empty LinkedListAllocator.
+    pub const fn new() -> Self {
+        Self {
+            head: ListNode::new(0),
+        }
+    }
+
+    /// Initialize the allocator with the given heap bounds.
+    ///
+    /// This function is unsafe because the caller must guarantee that the given
+    /// heap bounds are valid and that the heap is unused. This method must be
+    /// called only once.
+    pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
+        self.add_free_region(heap_start, heap_size);
+    }
+
+    /// Adds the given memory region to the front of the list.
+    unsafe fn add_free_region(&mut self, addr: usize, size: usize) {
+        todo!();
+    }
+}

src/lib.rs

@@ -3,6 +3,7 @@
 #![feature(custom_test_frameworks)]
 #![feature(abi_x86_interrupt)]
 #![feature(alloc_error_handler)]
+#![feature(const_fn)]
 #![test_runner(crate::test_runner)]
 #![reexport_test_harness_main = "test_main"]