mirror of
https://github.com/autc04/Retro68.git
synced 2024-09-08 20:55:01 +00:00
59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
/* $NetBSD: tsearch.c,v 1.3 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: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem Exp $");
|
|
#endif /* LIBC_SCCS and not lint */
|
|
#endif
|
|
|
|
#include <assert.h>
|
|
#define _SEARCH_PRIVATE
|
|
#include <search.h>
|
|
#include <stdlib.h>
|
|
|
|
/* find or insert datum into search tree */
|
|
void *
|
|
_DEFUN(tsearch, (vkey, vrootp, compar),
|
|
const void *vkey _AND /* key to be located */
|
|
void **vrootp _AND /* address of tree root */
|
|
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 */
|
|
/* LINTED const castaway ok */
|
|
q->key = (void *)vkey; /* initialize new node */
|
|
q->llink = q->rlink = NULL;
|
|
}
|
|
return q;
|
|
}
|