Implement GlobalAlloc for BumpAllocator

src/allocator/bump.rs

@@ -1,3 +1,7 @@
+use super::{align_up, Locked};
+use alloc::alloc::{GlobalAlloc, Layout};
+use core::ptr;
+
 pub struct BumpAllocator {
     heap_start: usize,
     heap_end: usize,
@@ -26,3 +30,29 @@ impl BumpAllocator {
         self.next = heap_start;
     }
 }
+
+unsafe impl GlobalAlloc for Locked<BumpAllocator> {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        let mut bump = self.lock(); // get a mutable reference
+
+        let alloc_start = align_up(bump.next, layout.align());
+        let alloc_end = alloc_start + layout.size();
+
+        if alloc_end > bump.heap_end {
+            ptr::null_mut() // out of memory
+        } else {
+            bump.next = alloc_end;
+            bump.allocations += 1;
+            alloc_start as *mut u8
+        }
+    }
+
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
+        let mut bump = self.lock(); // get a mutable reference
+
+        bump.allocations -= 1;
+        if bump.allocations == 0 {
+            bump.next = bump.heap_start;
+        }
+    }
+}