1 /* $NetBSD: tsearch.c,v 1.3 1999/09/16 11:45:37 lukem 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 1.3 1999/09/16 11:45:37 lukem 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(vkey, vrootp, compar) 29 const void *vkey; /* key to be located */ 30 void **vrootp; /* address of tree root */ 31 int (*compar)(const void *, const void *); 32 { 33 node_t *q; 34 node_t **rootp = (node_t **)vrootp; 35 36 if (rootp == NULL) 37 return NULL; 38 39 while (*rootp != NULL) { /* Knuth's T1: */ 40 int r; 41 42 if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */ 43 return *rootp; /* we found it! */ 44 45 rootp = (r < 0) ? 46 &(*rootp)->llink : /* T3: follow left branch */ 47 &(*rootp)->rlink; /* T4: follow right branch */ 48 } 49 50 q = malloc(sizeof(node_t)); /* T5: key not found */ 51 if (q != 0) { /* make new node */ 52 *rootp = q; /* link new node to old */ 53 /* LINTED const castaway ok */ 54 q->key = (void *)vkey; /* initialize new node */ 55 q->llink = q->rlink = NULL; 56 } 57 return q; 58 } 59