hashtable.cpp

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/* src/toolbox/hashtable.c - functions for internal hashtables

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   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., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/


#include "toolbox/hashtable.hpp"
#include "threads/mutex.hpp"            // for Mutex
#include "vm/types.hpp"                 // for u4


/* hashtable_create ************************************************************

   Initializes a hashtable structure and allocates memory. The
   parameter size specifies the initial size of the hashtable.

*******************************************************************************/

void hashtable_create(hashtable *hash, u4 size)
{
    /* initialize locking pointer */

    /* We need to seperately allocate a mutex here, as we need to
       store the lock object in the new hashtable if it's resized.
       Otherwise we get an IllegalMonitorStateException. */

    hash->mutex   = new Mutex();

    /* set initial hash values */

    hash->size    = size;
    hash->entries = 0;
    hash->ptr     = MNEW(void*, size);

    /* MNEW always allocates memory zeroed out, no need to clear the table */
}


/* hashtable_resize ************************************************************

   Creates a new hashtable with specified size and moves the important
   stuff from the old hashtable.

*******************************************************************************/

hashtable *hashtable_resize(hashtable *hash, u4 size)
{
    hashtable *newhash;

    /* create new hashtable with specified size */

    newhash = NEW(hashtable);

    hashtable_create(newhash, size);

    /* We need to store the old lock object in the new hashtable.
       Otherwise we get an IllegalMonitorStateException. */

    delete newhash->mutex;

    newhash->mutex = hash->mutex;

    /* store the number of entries in the new hashtable */

    newhash->entries = hash->entries;

    return newhash;
}


/* hashtable_free **************************************************************

   Simply frees the hashtable.

   ATTENTION: It does NOT free the lock object!

*******************************************************************************/

void hashtable_free(hashtable *hash)
{
    MFREE(hash->ptr, void*, hash->size);
    FREE(hash, hashtable);
}


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