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/* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */

/*

 * Copyright (c) 2001 Christopher G. Demetriou

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. The name of the author may not be used to endorse or promote products

 *    derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * <<Id: LICENSE_GC,v 1.1 2001/10/01 23:24:05 cgd Exp>>

 */

/*

 * hcreate() / hsearch() / hdestroy()

 *

 * SysV/XPG4 hash table functions.

 *

 * Implementation done based on NetBSD manual page and Solaris manual page,

 * plus my own personal experience about how they're supposed to work.

 *

 * I tried to look at Knuth (as cited by the Solaris manual page), but

 * nobody had a copy in the office, so...

 */

#include <sys/cdefs.h>

#if 0

#if defined(LIBC_SCCS) && !defined(lint)

__RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $");

#endif /* LIBC_SCCS and not lint */

#endif

#include <sys/types.h>

#include <sys/queue.h>

#include <errno.h>

#include <search.h>

#include <stdlib.h>

#include <string.h>

/*

 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit

 * ptr machine) without adjusting MAX_BUCKETS_LG2 below.

 */

struct internal_entry {

        SLIST_ENTRY(internal_entry) link;

        ENTRY ent;

};

SLIST_HEAD(internal_head, internal_entry);

#define MIN_BUCKETS_LG2 4

#define MIN_BUCKETS     (1 << MIN_BUCKETS_LG2)

/*

 * max * sizeof internal_entry must fit into size_t.

 * assumes internal_entry is <= 32 (2^5) bytes.

 */

#define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5)

#define MAX_BUCKETS     ((size_t)1 << MAX_BUCKETS_LG2)

/* Default hash function, from db/hash/hash_func.c */

extern __uint32_t (*__default_hash)(const void *, size_t);

int

hcreate_r(size_t nel, struct hsearch_data *htab)

{

        size_t idx;

        unsigned int p2;

        /* Make sure this this isn't called when a table already exists. */

        if (htab->htable != NULL) {

                errno = EINVAL;

                return 0;

        }

        /* If nel is too small, make it min sized. */

        if (nel < MIN_BUCKETS)

                nel = MIN_BUCKETS;

        /* If it's too large, cap it. */

        if (nel > MAX_BUCKETS)

                nel = MAX_BUCKETS;

        /* If it's is not a power of two in size, round up. */

        if ((nel & (nel - 1)) != 0) {

                for (p2 = 0; nel != 0; p2++)

                        nel >>= 1;

                nel = 1 << p2;

        }

        /* Allocate the table. */

        htab->htablesize = nel;

        htab->htable = malloc(htab->htablesize * sizeof htab->htable[0]);

        if (htab->htable == NULL) {

                errno = ENOMEM;

                return 0;

        }

        /* Initialize it. */

        for (idx = 0; idx < htab->htablesize; idx++)

                SLIST_INIT(&(htab->htable[idx]));

        return 1;

}

void

hdestroy_r(struct hsearch_data *htab)

{

        struct internal_entry *ie;

        size_t idx;

        if (htab->htable == NULL)

                return;

#if 0

        for (idx = 0; idx < htab->htablesize; idx++) {

                while (!SLIST_EMPTY(&(htab->htable[idx]))) {

                        ie = SLIST_FIRST(&(htab->htable[idx]));

                        SLIST_REMOVE_HEAD(&(htab->htable[idx]), link);

                        free(ie->ent.key);

                        free(ie);

                }

        }

#endif

        free(htab->htable);

        htab->htable = NULL;

}

int

hsearch_r(ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab)

{

        struct internal_head *head;

        struct internal_entry *ie;

        __uint32_t hashval;

        size_t len;

        len = strlen(item.key);

        hashval = (*__default_hash)(item.key, len);

        head = &(htab->htable[hashval & (htab->htablesize - 1)]);

        ie = SLIST_FIRST(head);

        while (ie != NULL) {

                if (strcmp(ie->ent.key, item.key) == 0)

                        break;

                ie = SLIST_NEXT(ie, link);

        }

        if (ie != NULL)

          {

            *retval = &ie->ent;

            return 1;

          }

        else if (action == FIND)

          {

            *retval = NULL;

            return 0;

          }

        ie = malloc(sizeof *ie);

        if (ie == NULL)

          {

            *retval = NULL;

            return 0;

          }

        ie->ent.key = item.key;

        ie->ent.data = item.data;

        SLIST_INSERT_HEAD(head, ie, link);

        *retval = &ie->ent;

        return 1;

}