newlib/libc/search/tfind.c

   1 /*      $NetBSD: tfind.c,v 1.2 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: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $");
  18 #endif /* LIBC_SCCS and not lint */
  19 #endif
  20
  21 #include <assert.h>
  22 #define _SEARCH_PRIVATE
  23 #include <stdlib.h>
  24 #include <search.h>
  25
  26 /* find a node, or return 0 */
  27 void *
  28 tfind (const void *vkey,                /* key to be found */
  29         void **vrootp,          /* address of the tree root */
  30         int (*compar)(const void *, const void *))
  31 {
  32         node_t **rootp = (node_t **)vrootp;
  33
  34         if (rootp == NULL)
  35                 return NULL;
  36
  37         while (*rootp != NULL) {                /* T1: */
  38                 int r;
  39
  40                 if ((r = (*compar)(vkey, (*rootp)->key)) == 0)  /* T2: */
  41                         return *rootp;          /* key found */
  42                 rootp = (r < 0) ?
  43                     &(*rootp)->llink :          /* T3: follow left branch */
  44                     &(*rootp)->rlink;           /* T4: follow right branch */
  45         }
  46         return NULL;
  47 }