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      1 /*	$NetBSD: tfind.c,v 1.7 2012/06/25 22:32:45 abs Exp $	*/
      2 
      3 /*
      4  * Tree search generalized from Knuth (6.2.2) Algorithm T just like
      5  * the AT&T man page says.
      6  *
      7  * The node_t structure is for internal use only, lint doesn't grok it.
      8  *
      9  * Written by reading the System V Interface Definition, not the code.
     10  *
     11  * Totally public domain.
     12  */
     13 
     14 #include <sys/cdefs.h>
     15 #if defined(LIBC_SCCS) && !defined(lint)
     16 __RCSID("$NetBSD: tfind.c,v 1.7 2012/06/25 22:32:45 abs Exp $");
     17 #endif /* LIBC_SCCS and not lint */
     18 
     19 #include <assert.h>
     20 #define _SEARCH_PRIVATE
     21 #include <stdlib.h>
     22 #include <search.h>
     23 
     24 /* find a node by key "vkey" in tree "vrootp", or return 0 */
     25 void *
     26 tfind(const void *vkey, void * const *vrootp,
     27     int (*compar)(const void *, const void *))
     28 {
     29 	node_t * const *rootp = (node_t * const*)vrootp;
     30 
     31 	_DIAGASSERT(vkey != NULL);
     32 	_DIAGASSERT(compar != NULL);
     33 
     34 	if (rootp == NULL)
     35 		return NULL;
     36 
     37 	while (*rootp != NULL) {		/* T1: */
     38 		int r;
     39 
     40 		if ((r = (*compar)(vkey, (*rootp)->key)) == 0)	/* T2: */
     41 			return *rootp;		/* key found */
     42 		rootp = (r < 0) ?
     43 		    &(*rootp)->llink :		/* T3: follow left branch */
     44 		    &(*rootp)->rlink;		/* T4: follow right branch */
     45 	}
     46 	return NULL;
     47 }
     48