[PATCH v3 09/17] lib min_heap: Add min_heap_sift_up()

Kuan-Wei Chiu
2024-04-06T16:48:25Z

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

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
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 9391f7cc9da9..201f59cb3558 100644
--- a/include/linux/min_heap.h
+++ b/include/linux/min_heap.h
@@ -111,6 +111,26 @@ void __min_heapify(min_heap_char *heap, int pos, size_t elem_size,
#define min_heapify(_heap, _pos, _func, _args) \
__min_heapify((min_heap_char *)_heap, _pos, __minheap_obj_size(_heap), _func, _args)

+/* Sift up ith element from the heap, O(log2(nr)). */
+static __always_inline
+void __min_heap_sift_up(min_heap_char *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((min_heap_char *)_heap, __minheap_obj_size(_heap), _idx, _func, _args)
+
/* Floyd's approach to heapification that is O(nr). */
static __always_inline
void __min_heapify_all(min_heap_char *heap, size_t elem_size,
--
2.34.1