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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 1998-2009. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*
*/
#include <stdlib.h>
#include "hash.h"
/* move the elements from oldtab to a new table newsize. The old table
* is freed and the caller should discard the pointer. On failure
* (i.e. if malloc fails) return the old table and do nothing.
*/
ei_hash *ei_hash_resize(ei_hash *oldtab, int newsize)
{
ei_hash *newtab=NULL;
ei_bucket *b, *next;
int i,h;
/* make sure size is odd, then increase until prime */
newsize |= 0x1;
while (!ei_isprime(newsize)) newsize +=2;
if (newsize == oldtab->size) return oldtab;
/* make a new table */
if (!(newtab = ei_hash_newtab(newsize))) return oldtab;
newtab->hash = oldtab->hash;
/* move the buckets, rehashing */
/* note that this will reverse the order of any chains */
for (i=0; i<oldtab->size; i++) {
b=oldtab->tab[i];
while (b) {
next = b->next;
h = b->rawhash % newtab->size;
b->next=newtab->tab[h];
if (!newtab->tab[h]) newtab->npos++;
newtab->tab[h]=b;
b = next;
}
}
/* the new table has the same number of elements as the old one */
newtab->nelem = oldtab->nelem;
/* the new table takes over the freelist from the old one */
newtab->freelist = oldtab->freelist;
/* now it's safe to remove the old table */
free(oldtab);
return newtab;
}
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