/* $OpenBSD: ohash_do.c,v 1.4 2004/06/22 20:00:16 espie Exp $ */
/* ex:ts=8 sw=4:
 */

/* Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * $FreeBSD: src/usr.bin/m4/lib/ohash_do.c,v 1.2 2012/11/17 01:54:24 svnexp Exp $
 */

#include "ohash_int.h"

static void ohash_resize(struct ohash *);

static void
ohash_resize(struct ohash *h)
{
        struct _ohash_record *n;
        unsigned int    ns, j;
        unsigned int    i, incr;

        if (4 * h->deleted < h->total)
                ns = h->size << 1;
        else if (3 * h->deleted > 2 * h->total)
                ns = h->size >> 1;
        else
                ns = h->size;
        if (ns < MINSIZE)
                ns = MINSIZE;
#ifdef STATS_HASH
        STAT_HASH_EXPAND++;
        STAT_HASH_SIZE += ns - h->size;
#endif
        n = (h->info.halloc)(sizeof(struct _ohash_record) * ns, h->info.data);
        if (n == NULL)
                return;

        for (j = 0; j < h->size; j++) {
                if (h->t[j].p != NULL && h->t[j].p != DELETED) {
                        i = h->t[j].hv % ns;
                        incr = ((h->t[j].hv % (ns - 2)) & ~1) + 1;
                        while (n[i].p != NULL) {
                                i += incr;
                                if (i >= ns)
                                        i -= ns;
                        }
                        n[i].hv = h->t[j].hv;
                        n[i].p = h->t[j].p;
                }
        }
        (h->info.hfree)(h->t, sizeof(struct _ohash_record) * h->size,
            h->info.data);
        h->t = n;
        h->size = ns;
        h->total -= h->deleted;
        h->deleted = 0;
}

void *
ohash_remove(struct ohash *h, unsigned int i)
{
        void *result = __DECONST(void *, h->t[i].p);

        if (result == NULL || result == DELETED)
                return NULL;

#ifdef STATS_HASH
        STAT_HASH_ENTRIES--;
#endif
        h->t[i].p = DELETED;
        h->deleted++;
        if (h->deleted >= MINDELETED && 4 * h->deleted > h->total)
                ohash_resize(h);
        return result;
}

void *
ohash_find(struct ohash *h, unsigned int i)
{
        if (h->t[i].p == DELETED)
                return NULL;
        else
                return __DECONST(void *, h->t[i].p);
}

void *
ohash_insert(struct ohash *h, unsigned int i, void *p)
{
#ifdef STATS_HASH
        STAT_HASH_ENTRIES++;
#endif
        if (h->t[i].p == DELETED) {
                h->deleted--;
                h->t[i].p = p;
        } else {
                h->t[i].p = p;
                /* Arbitrary resize boundary.  Tweak if not efficient enough. */
                if (++h->total * 4 > h->size * 3)
                        ohash_resize(h);
        }
        return p;
}