diff options
Diffstat (limited to 'lib/libc/stdlib/tsearch.c')
-rw-r--r-- | lib/libc/stdlib/tsearch.c | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/lib/libc/stdlib/tsearch.c b/lib/libc/stdlib/tsearch.c new file mode 100644 index 0000000..149c2bb --- /dev/null +++ b/lib/libc/stdlib/tsearch.c @@ -0,0 +1,58 @@ +/* $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 $"); +#endif /* LIBC_SCCS and not lint */ +#endif +__FBSDID("$FreeBSD$"); + +#define _SEARCH_PRIVATE +#include <search.h> +#include <stdlib.h> + +/* find or insert datum into search tree */ +void * +tsearch(vkey, vrootp, compar) + const void *vkey; /* key to be located */ + void **vrootp; /* 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; +} |