48 lines
1.1 KiB
C
48 lines
1.1 KiB
C
/* $NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem 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: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $");
|
|
#endif /* LIBC_SCCS and not lint */
|
|
#endif
|
|
|
|
#include <assert.h>
|
|
#define _SEARCH_PRIVATE
|
|
#include <stdlib.h>
|
|
#include <search.h>
|
|
|
|
/* find a node, or return 0 */
|
|
void *
|
|
tfind (const void *vkey, /* key to be found */
|
|
void **vrootp, /* address of the tree root */
|
|
int (*compar)(const void *, const void *))
|
|
{
|
|
node_t **rootp = (node_t **)vrootp;
|
|
|
|
if (rootp == NULL)
|
|
return NULL;
|
|
|
|
while (*rootp != NULL) { /* T1: */
|
|
int r;
|
|
|
|
if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
|
|
return *rootp; /* key found */
|
|
rootp = (r < 0) ?
|
|
&(*rootp)->llink : /* T3: follow left branch */
|
|
&(*rootp)->rlink; /* T4: follow right branch */
|
|
}
|
|
return NULL;
|
|
}
|