rbtree: add rb_search_exact()HEADmaster

Sometimes we want to search for an exact key only, and reject the case
when tree->key < key. Add rb_search_exact() for this purpose, rather
than forcing the caller to perform the comparison in open code.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

2 files changed, 13 insertions, 0 deletions

diff --git a/include/rbtree.h b/include/rbtree.h
index 332f6f85..39d45aff 100644
--- a/include/rbtree.h
+++ b/include/rbtree.h
@@ -73,6 +73,11 @@ struct rbtree *rb_insert(struct rbtree *, struct rbtree *);
 struct rbtree *rb_search(const struct rbtree *, uint64_t);
 
 /*
+ * Find a node in the tree exactly matching the key value.
+ */
+struct rbtree *rb_search_exact(const struct rbtree *, uint64_t);
+
+/*
  * Return the immediately previous or next node in key order.
  * Returns NULL if this node is the end of the tree.
  * These operations are safe for complee (but not partial!)
diff --git a/nasmlib/rbtree.c b/nasmlib/rbtree.c
index 510f34b1..773338bb 100644
--- a/nasmlib/rbtree.c
+++ b/nasmlib/rbtree.c
@@ -87,6 +87,14 @@ struct rbtree *rb_search(const struct rbtree *tree, uint64_t key)
     return (struct rbtree *)best;
 }
 
+struct rbtree *rb_search_exact(const struct rbtree *tree, uint64_t key)
+{
+    struct rbtree *rv;
+
+    rv = rb_search(tree, key);
+    return (rv && rv->key == key) ? rv : NULL;
+}
+
 /* Reds two left in a row? */
 static inline bool is_red_left_left(struct rbtree *h)
 {