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/* $Id: hashtab.c,v 1.2 1999/03/27 16:33:30 dm Exp $ */
/*
*
* Copyright (C) 1998, 1999 David Mazieres (dm@uun.org)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
*/
#include "sysconf.h"
#include "hashtab.h"
/* Some prime numbers <= powers of 2 */
const u_int exp2primes[33] = {
0x1, /* place holder */
0x2, 0x3, 0x7, 0xd,
0x1f, 0x3d, 0x7f, 0xfb,
0x1fd, 0x3fd, 0x7f7, 0xffd,
0x1fff, 0x3ffd, 0x7fed, 0xfff1,
0x1ffff, 0x3fffb, 0x7ffff, 0xffffd,
0x1ffff7, 0x3ffffd, 0x7ffff1, 0xfffffd,
0x1ffffd9, 0x3fffffb, 0x7ffffd9, 0xfffffc7,
0x1ffffffd, 0x3fffffdd, 0x7fffffff, 0xfffffffb,
};
/* Highest bit set in a byte */
const char bytemsb[0x100] = {
0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
};
/* Find last set (most significant bit) */
static inline u_int
fls32 (u_int32_t v)
{
if (v & 0xffff0000) {
if (v & 0xff000000)
return 24 + bytemsb[v>>24];
else
return 16 + bytemsb[v>>16];
}
if (v & 0x0000ff00)
return 8 + bytemsb[v>>8];
else
return bytemsb[v];
}
static inline int
log2c (u_int32_t v)
{
return v ? (int) fls32 (v - 1) : -1;
}
#define hteof(p) ((struct hashtab_entry *) ((char *) (p) + eos))
void
_hashtab_grow (struct _hashtab *htp, u_int eos)
{
u_int nbuckets;
void **ntab;
void *p, *np;
u_int i;
/* warn ("_hashtab_grow\n"); */
nbuckets = exp2primes[log2c(htp->ht_buckets)+1];
if (nbuckets < 3)
nbuckets = 3;
ntab = malloc (nbuckets * sizeof (*ntab));
if (!ntab)
return;
bzero (ntab, nbuckets * sizeof (*ntab));
for (i = 0; i < htp->ht_buckets; i++)
for (p = htp->ht_tab[i]; p; p = np) {
struct hashtab_entry *htep = hteof (p);
u_int ni = htep->hte_hval % nbuckets;
np = htep->hte_next;
htep->hte_next = ntab[ni];
htep->hte_prev = &ntab[ni];
if (ntab[ni])
hteof(ntab[ni])->hte_prev = &htep->hte_next;
ntab[ni] = p;
}
xfree (htp->ht_tab);
htp->ht_tab = ntab;
htp->ht_buckets = nbuckets;
}
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