1 files changed, 57 insertions, 0 deletions

diff --git a/lib/libc/stdlib/tsearch.c b/lib/libc/stdlib/tsearch.c
new file mode 100644
index 000000000000..85832ce480a3
--- /dev/null
+++ b/lib/libc/stdlib/tsearch.c
@@ -0,0 +1,57 @@
+/*	$NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $	*/
+/* $FreeBSD$ */
+
+/*
+ * Tree search generalized from Knuth (6.2.2) Algorithm T just like
+ * the AT&T man page says.
+ *
+ * The node_t structure is for internal use only, lint doesn't grok it.
+ *
+ * Written by reading the System V Interface Definition, not the code.
+ *
+ * Totally public domain.
+ */
+
+#include <sys/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $");
+#endif /* LIBC_SCCS and not lint */
+
+#include <assert.h>
+#define _SEARCH_PRIVATE
+#include <search.h>
+#include <stdlib.h>
+
+/* find or insert datum into search tree */
+void *
+tsearch(vkey, vrootp, compar)
+	const void *vkey;		/* key to be located */
+	void **vrootp;			/* address of tree root */
+	int (*compar) __P((const void *, const void *));
+{
+	node_t *q;
+	node_t **rootp = (node_t **)vrootp;
+
+	if (rootp == NULL)
+		return NULL;
+
+	while (*rootp != NULL) {	/* Knuth's T1: */
+		int r;
+
+		if ((r = (*compar)(vkey, (*rootp)->key)) == 0)	/* T2: */
+			return *rootp;		/* we found it! */
+
+		rootp = (r < 0) ?
+		    &(*rootp)->llink :		/* T3: follow left branch */
+		    &(*rootp)->rlink;		/* T4: follow right branch */
+	}
+
+	q = malloc(sizeof(node_t));		/* T5: key not found */
+	if (q != 0) {				/* make new node */
+		*rootp = q;			/* link new node to old */
+		/* LINTED const castaway ok */
+		q->key = (void *)vkey;		/* initialize new node */
+		q->llink = q->rlink = NULL;
+	}
+	return q;
+}