vppinfra: add basic rbtree

Algorithm from CLRS, Introduction to Algorithms 3rd Edition, Ch. 13

Change-Id: I5bc2c507593770939cd5584f21dacf36ebd2b4c1
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 84 insertions, 0 deletions

diff --git a/src/vppinfra/rbtree.h b/src/vppinfra/rbtree.h
new file mode 100644
index 00000000000..ace07ac5622
--- /dev/null
+++ b/src/vppinfra/rbtree.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2019 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SRC_VPPINFRA_RBTREE_H_
+#define SRC_VPPINFRA_RBTREE_H_
+
+#include <vppinfra/types.h>
+#include <vppinfra/pool.h>
+
+#define RBTREE_TNIL_INDEX 0
+
+typedef u32 rb_node_index_t;
+
+typedef enum rb_tree_color_
+{
+  RBTREE_RED,
+  RBTREE_BLACK
+} rb_node_color_t;
+
+typedef struct rb_node_
+{
+  u8 color;			/**< node color */
+  rb_node_index_t parent;	/**< parent index */
+  rb_node_index_t left;		/**< left child index */
+  rb_node_index_t right;	/**< right child index */
+  u32 key;			/**< node key */
+  u32 opaque;			/**< value stored by node */
+} rb_node_t;
+
+typedef struct rb_tree_
+{
+  rb_node_t *nodes;		/**< pool of nodes */
+  rb_node_index_t root;		/**< root index */
+} rb_tree_t;
+
+void rb_tree_init (rb_tree_t * rt);
+rb_node_index_t rb_tree_add (rb_tree_t * rt, u32 key);
+rb_node_index_t rb_tree_add2 (rb_tree_t * rt, u32 key, u32 opaque);
+void rb_tree_del (rb_tree_t * rt, u32 key);
+void rb_tree_free_nodes (rb_tree_t * rt);
+u32 rb_tree_n_nodes (rb_tree_t * rt);
+rb_node_t *rb_tree_min_subtree (rb_tree_t * rt, rb_node_t * x);
+rb_node_t *rb_tree_max_subtree (rb_tree_t * rt, rb_node_t * x);
+rb_node_t *rb_tree_search_subtree (rb_tree_t * rt, rb_node_t * x, u32 key);
+
+static inline rb_node_index_t
+rb_node_index (rb_tree_t * rt, rb_node_t * n)
+{
+  return n - rt->nodes;
+}
+
+static inline u8
+rb_node_is_tnil (rb_tree_t * rt, rb_node_t * n)
+{
+  return rb_node_index (rt, n) == RBTREE_TNIL_INDEX;
+}
+
+static inline rb_node_t *
+rb_node (rb_tree_t * rt, rb_node_index_t ri)
+{
+  return pool_elt_at_index (rt->nodes, ri);
+}
+
+#endif /* SRC_VPPINFRA_RBTREE_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */