Optimized code by adding last block global variable.

main.c

@@ -13,13 +13,13 @@ struct block
 	int free;
 };
 
-struct block* freeList = NULL;
+struct block* first = NULL;
+struct block* last = NULL;
 
 /// Extends heap memory upwards, towards zero.
-/// @param [in] last The last block that the newly created block will link to.
 /// @param [in] s The size of the memory needed aligned by 4 bytes.
 /// @returns The new memory block.
-struct block* extend_heap(struct block* last, size_t s)
+struct block* extend_heap(size_t s)
 {
 	struct block* b = sbrk(0);
 
@@ -33,6 +33,8 @@ struct block* extend_heap(struct block* last, size_t s)
 	if (last)
 		last->next = b;
 
+	last = b;
+
 	return b;
 }
 
@@ -41,24 +43,13 @@ struct block* extend_heap(struct block* last, size_t s)
 /// @returns The matching available memory block.
 struct block* find_first(size_t s)
 {
-	struct block* current = freeList;
+	struct block* current = first;
 	while (current && (!current->free || current->size < s))
 		current = current->next;
 
 	return current;
 }
 
-/// Finds the last memory block in the linked list to attach a new block to.
-/// @returns The last memory block.
-struct block* find_last()
-{
-	struct block* current = freeList;
-	while (current && current->next)
-		current = freeList->next;
-
-	return current;
-}
-
 /// Will find or allocate a memory block.
 /// @param [in] size The size of the memory block to request.
 /// @returns The requested memory on the heap.
@@ -69,11 +60,13 @@ void* malloc(size_t size)
 
 	size_t alignedSize = ALIGN4(size);
 
-	if (freeList)
+	if (first)
 	{
 		b = find_first(alignedSize);
 		if (!b)
-			b = extend_heap(find_last(), alignedSize);
+		{
+			b = extend_heap(alignedSize);
+		}
 		/*
 		else
 		 	Fragment here if possible.
@@ -81,11 +74,11 @@ void* malloc(size_t size)
 	}
 	else
 	{
-		b = extend_heap(NULL, alignedSize);
+		b = extend_heap(alignedSize);
 		if (!b)
 			return NULL;
 
-		freeList = b;
+		first = b;
 	}
 
 	return b + 1;