From a5c50e74084e6cf08801dff48e90c378e8ce25f1 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Fri, 10 Jan 2020 11:52:04 +0100
Subject: [PATCH] Implement GlobalAlloc for LinkedListAllocator

---
 src/allocator/linked_list.rs | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/allocator/linked_list.rs b/src/allocator/linked_list.rs
index 80c69131..079f7cdb 100644
--- a/src/allocator/linked_list.rs
+++ b/src/allocator/linked_list.rs
@@ -1,5 +1,6 @@
-use super::align_up;
-use core::mem;
+use super::{align_up, Locked};
+use alloc::alloc::{GlobalAlloc, Layout};
+use core::{mem, ptr};
 
 struct ListNode {
     size: usize,
@@ -103,3 +104,29 @@ impl LinkedListAllocator {
         Ok(alloc_start)
     }
 }
+
+unsafe impl GlobalAlloc for Locked<LinkedListAllocator> {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        // perform layout adjustments
+        let (size, align) = LinkedListAllocator::size_align(layout);
+        let mut allocator = self.inner.lock();
+
+        if let Some((region, alloc_start)) = allocator.find_region(size, align) {
+            let alloc_end = alloc_start + size;
+            let excess_size = region.end_addr() - alloc_end;
+            if excess_size > 0 {
+                allocator.add_free_region(alloc_end, excess_size);
+            }
+            alloc_start as *mut u8
+        } else {
+            ptr::null_mut()
+        }
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        // perform layout adjustments
+        let (size, _) = LinkedListAllocator::size_align(layout);
+
+        self.inner.lock().add_free_region(ptr as usize, size)
+    }
+}