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slab.h
/* slab.h
 * Definitions for very simple slab handling
 *
 * $Id: slab.h 18197 2006-05-21 05:12:17Z sahlberg $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * 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
 * of the License, 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.
 */

#ifndef __SLAB_H__
#define __SLAB_H__

#define NITEMS_PER_SLAB 100

/*
 * Generate declaration of a union type containing the specified type of
 * slab-allocated item, and a pointer to an object of that type, for use
 * in the macros below.
 */
#define SLAB_ITEM_TYPE_DEFINE(type)             \
      union type ## slab_item {                 \
            type slab_item;                     \
            union type ## slab_item *next_free; \
      };

/*
 * Generate definition of the free list pointer.
 */
#define SLAB_FREE_LIST_DEFINE(type)       \
      union type ## slab_item *type ## _free_list = NULL;

/*
 * Generate an external declaration of the free list pointer.
 */
#define SLAB_FREE_LIST_DECLARE(type)            \
      union type ## slab_item *type ## _free_list;

/* we never free any memory we have allocated, when it is returned to us
   we just store it in the free list until (hopefully) it gets used again
*/
#define SLAB_ALLOC(item, type)                              \
      if(!type ## _free_list){                        \
            int i;                                    \
            union type ## slab_item *tmp;             \
            tmp=g_malloc(NITEMS_PER_SLAB*sizeof(*tmp));     \
            for(i=0;i<NITEMS_PER_SLAB;i++){                 \
                  tmp[i].next_free = type ## _free_list;    \
                  type ## _free_list = &tmp[i];       \
            }                                   \
      }                                         \
      item = &(type ## _free_list->slab_item);        \
      type ## _free_list = type ## _free_list->next_free;

#define SLAB_FREE(item, type)                               \
{                                                     \
      ((union type ## slab_item *)item)->next_free = type ## _free_list;      \
      type ## _free_list = (union type ## slab_item *)item;       \
}

#endif /* slab.h */

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