1 /* $NetBSD: tsearch.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 0 16 #if defined(LIBC_SCCS) && !defined(lint) 17 __RCSID("$NetBSD: tsearch.c,v 1.7 2012/06/25 22:32:45 abs Exp $"); 18 #endif /* LIBC_SCCS and not lint */ 19 #endif 20 __FBSDID("$FreeBSD$"); 21 22 #define _SEARCH_PRIVATE 23 #include <search.h> 24 #include <stdlib.h> 25 26 /* find or insert datum into search tree */ 27 void * 28 tsearch(const void *vkey, void **vrootp, 29 int (*compar)(const void *, const void *)) 30 { 31 node_t *q; 32 node_t **rootp = (node_t **)vrootp; 33 34 if (rootp == NULL) 35 return NULL; 36 37 while (*rootp != NULL) { /* Knuth's T1: */ 38 int r; 39 40 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 41 return *rootp; /* we found it! */ 42 43 rootp = (r < 0) ? 44 &(*rootp)->llink : /* T3: follow left branch */ 45 &(*rootp)->rlink; /* T4: follow right branch */ 46 } 47 48 q = malloc(sizeof(node_t)); /* T5: key not found */ 49 if (q != 0) { /* make new node */ 50 *rootp = q; /* link new node to old */ 51 q->key = __DECONST(void *, vkey);/* initialize new node */ 52 q->llink = q->rlink = NULL; 53 } 54 return q; 55 } 56