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/* emem.c
* Ethereal memory management and garbage collection functions
* Ronnie Sahlberg 2005
*
* $Id$
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* 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.
*/
#include <stdio.h>
#include <stdlib.h>
#include <glib.h>
#include "emem.h"
/* When required, allocate more memory from the OS in this size chunks */
#define EMEM_PACKET_CHUNK_SIZE 10485760
typedef struct _emem_chunk_t {
struct _emem_chunk_t *next;
unsigned int amount_free;
unsigned int free_offset;
char *buf;
} emem_chunk_t;
typedef struct _emem_header_t {
emem_chunk_t *free_list;
emem_chunk_t *used_list;
} emem_header_t;
static emem_header_t emem_packet_mem;
/* Initialize the packet-lifetime memory allocation pool.
* This function should be called only once when Etehreal or Tethereal starts
* up.
*/
void
ep_init_chunk(void)
{
emem_packet_mem.free_list=NULL;
emem_packet_mem.used_list=NULL;
}
/* allocate 'size' amount of memory with an allocation lifetime until the
* next packet.
*/
void *
ep_alloc(size_t size)
{
void *buf;
/* round up to 8 byte boundary */
if(size&0x07){
size=(size+7)&0xfffffff8;
}
/* make sure we dont try to allocate too much (arbitrary limit) */
g_assert(size<(EMEM_PACKET_CHUNK_SIZE>>2));
/* we dont have any free data, so we must allocate a new one */
if(!emem_packet_mem.free_list){
emem_chunk_t *npc;
npc=g_malloc(sizeof(emem_chunk_t));
npc->next=NULL;
npc->amount_free=EMEM_PACKET_CHUNK_SIZE;
npc->free_offset=0;
npc->buf=g_malloc(EMEM_PACKET_CHUNK_SIZE);
emem_packet_mem.free_list=npc;
}
/* oops, we need to allocate more memory to serve this request
* than we have free. move this node to the used list and try again
*/
if(size>emem_packet_mem.free_list->amount_free){
emem_chunk_t *npc;
npc=emem_packet_mem.free_list;
emem_packet_mem.free_list=emem_packet_mem.free_list->next;
npc->next=emem_packet_mem.used_list;
emem_packet_mem.used_list=npc;
}
/* we dont have any free data, so we must allocate a new one */
if(!emem_packet_mem.free_list){
emem_chunk_t *npc;
npc=g_malloc(sizeof(emem_chunk_t));
npc->next=NULL;
npc->amount_free=EMEM_PACKET_CHUNK_SIZE;
npc->free_offset=0;
npc->buf=g_malloc(EMEM_PACKET_CHUNK_SIZE);
emem_packet_mem.free_list=npc;
}
buf=emem_packet_mem.free_list->buf+emem_packet_mem.free_list->free_offset;
emem_packet_mem.free_list->amount_free-=size;
emem_packet_mem.free_list->free_offset+=size;
return buf;
}
/* release all allocated memory back to the pool.
*/
void
ep_free_all(void)
{
emem_chunk_t *npc;
/* move all used chunks ove to the free list */
while(emem_packet_mem.used_list){
npc=emem_packet_mem.used_list;
emem_packet_mem.used_list=emem_packet_mem.used_list->next;
npc->next=emem_packet_mem.free_list;
emem_packet_mem.free_list=npc;
}
/* clear them all out */
for(npc=emem_packet_mem.free_list;npc;npc=npc->next){
npc->amount_free=EMEM_PACKET_CHUNK_SIZE;
npc->free_offset=0;
}
}
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