Add FixedSizeBlockAllocator type

src/allocator/fixed_size_block.rs

@@ -7,3 +7,27 @@ const BLOCK_SIZES: &[usize] = &[8, 16, 32, 64, 128, 256, 512, 1024, 2048];
 struct ListNode {
     next: Option<&'static mut ListNode>,
 }
+
+pub struct FixedSizeBlockAllocator {
+    list_heads: [Option<&'static mut ListNode>; BLOCK_SIZES.len()],
+    fallback_allocator: linked_list_allocator::Heap,
+}
+
+impl FixedSizeBlockAllocator {
+    /// Creates an empty FixedSizeBlockAllocator.
+    pub const fn new() -> Self {
+        FixedSizeBlockAllocator {
+            list_heads: [None; BLOCK_SIZES.len()],
+            fallback_allocator: linked_list_allocator::Heap::empty(),
+        }
+    }
+
+    /// 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.fallback_allocator.init(heap_start, heap_size);
+    }
+}

src/lib.rs

@@ -5,6 +5,7 @@
 #![feature(alloc_error_handler)]
 #![feature(const_fn)]
 #![feature(alloc_layout_extra)]
+#![feature(const_in_array_repeat_expressions)]
 #![test_runner(crate::test_runner)]
 #![reexport_test_harness_main = "test_main"]