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/* $NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs Exp $ */
/*
* 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 0
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs Exp $");
#endif /* LIBC_SCCS and not lint */
#endif
__FBSDID("$FreeBSD$");
#define _SEARCH_PRIVATE
#include <search.h>
#include <stdlib.h>
/* find or insert datum into search tree */
void *
tsearch(const void *vkey, void **vrootp,
int (*compar)(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 */
q->key = __DECONST(void *, vkey);/* initialize new node */
q->llink = q->rlink = NULL;
}
return q;
}
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