[PATCH 3/4] prio_tree: simplify prio_tree_expand

[Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>]

In current code, the deleted-node is recorded from first to last,
actually, we can directly attach these node on 'node' we will insert
as the left child, it can let the code more readable

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
---
 lib/prio_tree.c |   38 ++++++++++++++------------------------
 1 files changed, 14 insertions(+), 24 deletions(-)

diff --git a/lib/prio_tree.c b/lib/prio_tree.c
index 888e8b3..928482b 100644
--- a/lib/prio_tree.c
+++ b/lib/prio_tree.c
@@ -94,43 +94,33 @@ static inline unsigned long prio_tree_maxindex(unsigned int bits)
 static struct prio_tree_node *prio_tree_expand(struct prio_tree_root *root,
 		struct prio_tree_node *node, unsigned long max_heap_index)
 {
-	struct prio_tree_node *first = NULL, *prev, *last = NULL;
+	struct prio_tree_node *prev;

 	if (max_heap_index > prio_tree_maxindex(root->index_bits))
 		root->index_bits++;

+	prev = node;
+	INIT_PRIO_TREE_NODE(node);
+
 	while (max_heap_index > prio_tree_maxindex(root->index_bits)) {
+		struct prio_tree_node *tmp = root->prio_tree_node;
+
 		root->index_bits++;

 		if (prio_tree_empty(root))
 			continue;

-		if (first == NULL) {
-			first = root->prio_tree_node;
-			prio_tree_remove(root, root->prio_tree_node);
-			INIT_PRIO_TREE_NODE(first);
-			last = first;
-		} else {
-			prev = last;
-			last = root->prio_tree_node;
-			prio_tree_remove(root, root->prio_tree_node);
-			INIT_PRIO_TREE_NODE(last);
-			prev->left = last;
-			last->parent = prev;
-		}
-	}
-
-	INIT_PRIO_TREE_NODE(node);
+		prio_tree_remove(root, root->prio_tree_node);
+		INIT_PRIO_TREE_NODE(tmp);

-	if (first) {
-		node->left = first;
-		first->parent = node;
-	} else
-		last = node;
+		prev->left = tmp;
+		tmp->parent = prev;
+		prev = tmp;
+	}

 	if (!prio_tree_empty(root)) {
-		last->left = root->prio_tree_node;
-		last->left->parent = last;
+		prev->left = root->prio_tree_node;
+		prev->left->parent = prev;
 	}

 	root->prio_tree_node = node;
-- 
1.7.7.6

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