[PATCH 12/13] lib min_heap: Add min_heap_sift_up()

[Kuan-Wei Chiu]

Add min_heap_sift_up() to sift up the element at index 'idx' in the
heap.

Signed-off-by: Kuan-Wei Chiu <visitorckw@xxxxxxxxx>
---
 include/linux/min_heap.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/min_heap.h b/include/linux/min_heap.h
index ce085137fce7..586965977104 100644
--- a/include/linux/min_heap.h
+++ b/include/linux/min_heap.h
@@ -199,6 +199,26 @@ bool __min_heap_push(struct __min_heap *heap, const void *element, size_t elem_s
 #define min_heap_push(_heap, _element, _func, _args)	\
 	__min_heap_push(&(_heap)->heap, _element, __minheap_obj_size(_heap), _func, _args)
 
+/* Sift up ith element from the heap, O(log2(nr)). */
+static __always_inline
+void __min_heap_sift_up(struct __min_heap *heap, size_t elem_size, size_t idx,
+		const struct min_heap_callbacks *func, void *args)
+{
+	void *data = heap->data;
+	size_t parent;
+
+	while (idx) {
+		parent = (idx - 1) / 2;
+		if (func->less(data + parent * elem_size, data + idx * elem_size, args))
+			break;
+		func->swp(data + parent * elem_size, data + idx * elem_size, args);
+		idx = parent;
+	}
+}
+
+#define min_heap_sift_up(_heap, _idx, _func, _args)	\
+	__min_heap_sift_up(&(_heap)->heap, __minheap_obj_size(_heap), _idx, _func, _args)
+
 /* Remove ith element from the heap, O(log2(nr)). */
 static __always_inline
 bool __min_heap_del(struct __min_heap *heap, size_t elem_size, size_t idx,
-- 
2.34.1