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/* $NetBSD: tsearch.c,v 1.4 1999/09/20 04:39:43 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 <assert.h>
#define _SEARCH_PRIVATE
#include <search.h>
#include <stdlib.h>
/* find or insert datum into search tree */
void *
tsearch (const void * __restrict__ vkey, /* key to be located */
void ** __restrict__ vrootp, /* address of tree root */
int (*compar) (const void *, const void *))
{
node_t *q, **n;
node_t **rootp = (node_t **)vrootp;
if (rootp == NULL)
return NULL;
n = rootp;
while (*n != NULL)
{
/* Knuth's T1: */
int r;
if ((r = (*compar)(vkey, ((*n)->key))) == 0) /* T2: */
return *n; /* we found it! */
n = (r < 0) ?
&(*rootp)->llink : /* T3: follow left branch */
&(*rootp)->rlink; /* T4: follow right branch */
if (*n == NULL)
break;
rootp = n;
}
q = malloc(sizeof(node_t)); /* T5: key not found */
if (!q)
return q;
*n = q;
/* make new node */
/* LINTED const castaway ok */
q->key = (void *)vkey; /* initialize new node */
q->llink = q->rlink = NULL;
return q;
}
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