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/* wmem_slab.c
* Wireshark Memory Manager Slab Allocator
* Copyright 2012, Evan Huus <eapache@gmail.com>
*
* $Id$
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <string.h>
#include <glib.h>
#include "wmem_core.h"
#include "wmem_slab.h"
typedef struct _wmem_slab_chunk_t {
struct _wmem_slab_chunk_t *next;
} wmem_slab_chunk_t;
struct _wmem_slab_t {
size_t chunk_size;
wmem_slab_chunk_t *free_list;
wmem_allocator_t *allocator;
};
/* arbitrary, nice round value */
#define WMEM_CHUNKS_PER_ALLOC 8
static void
wmem_slab_alloc_chunks(wmem_slab_t *slab)
{
guint i;
guint8 *chunks;
wmem_slab_chunk_t *chunk;
/* We use a guint8 so that all the necessary pointer arithmetic is easy */
chunks = (guint8*) wmem_alloc(slab->allocator,
slab->chunk_size * WMEM_CHUNKS_PER_ALLOC);
/* Now pick each chunk out of the allocated block and add it to the
* slab's free_list */
for (i=0; i<WMEM_CHUNKS_PER_ALLOC; i++) {
chunk = (wmem_slab_chunk_t *) (chunks + (i * slab->chunk_size));
chunk->next = slab->free_list;
slab->free_list = chunk;
}
}
void *
wmem_slab_alloc(wmem_slab_t *slab)
{
wmem_slab_chunk_t *chunk;
if (slab->free_list == NULL) {
wmem_slab_alloc_chunks(slab);
}
chunk = slab->free_list;
slab->free_list = chunk->next;
return (void *) chunk;
}
void
wmem_slab_free(wmem_slab_t *slab, void *object)
{
wmem_slab_chunk_t *chunk;
chunk = (wmem_slab_chunk_t *) object;
chunk->next = slab->free_list;
slab->free_list = chunk;
}
wmem_slab_t *
wmem_create_slab(wmem_allocator_t *allocator, const size_t chunk_size)
{
wmem_slab_t *slab;
slab = wmem_alloc(allocator, sizeof(wmem_slab_t));
slab->chunk_size = (chunk_size > sizeof(wmem_slab_chunk_t)) ?
chunk_size :
sizeof(wmem_slab_chunk_t);
slab->free_list = NULL;
slab->allocator = allocator;
return slab;
}
/*
* Editor modelines - http://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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