cache.cc

来自「在NS-2环境中实现了移动Ad Hoc的两种广播算法:Flood和Bcast。里」· CC 代码 · 共 58 行

/*******************************************************************
 Copyright (C) 2004 Thomas Kunz, CRC Canada, BCAST for IPv4.
 DISTRIBUTED WITH NO WARRANTY, EXPRESS OR IMPLIED.
 See the GNU Library General Public License (file COPYING in the
 MANET_multicast directory) for conditions of use and redistribution.
*********************************************************************/

/*
 * Functions to manage a cache of packets. The cache is of fixed size
 * (determined at creation time) and managed in FIFO order.
 */

#include "MANET_multicast/cache.h"

/* Constructor */

PacketCache::PacketCache(int size) {
 cache = new Packet*[size];
 assert(cache);
 for (int i = 0; i < size; i++){
   cache[i] = (Packet *)NULL;
 }
 cache_size = size;
 current = 0;
}

/*
   Unique ID Management  Functions
*/

void
PacketCache::packet_insert(Packet* p) {
 if (cache[current] != NULL) {
   Packet::free(cache[current]);
 }
 cache[current] = p->copy();
 current = (current + 1) % cache_size;
}

Packet*
PacketCache::packet_lookup(nsaddr_t src, u_int32_t seqno) {
int i = 0;

 // Search the cache for a match of source and bid
 for (i = 0; i < cache_size; i++) {
   if (cache[i] != NULL) {
     struct hdr_ip *ih = HDR_IP(cache[i]);
     struct hdr_rtp *rh = HDR_RTP(cache[i]);
     nsaddr_t p_src = ih->saddr();
     unsigned int p_seqno = rh->seqno_;
     if (src == p_src && seqno == p_seqno) {
       return (cache[i]);
     }
   }
 }
 return ((Packet*)NULL);
}