uhd

/* -*- c++ -*- */

/*

 * Copyright 2009 Ettus Research LLC

 *

 * 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 3 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, see <http://www.gnu.org/licenses/>.

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#include "arp_cache.h"

#include <stddef.h>

typedef struct {

  struct ip_addr        ip;

  eth_mac_addr_t        mac;

} arp_cache_t;

#define        NENTRIES 8        // power-of-2

static size_t nentries;

static size_t victim;

static arp_cache_t cache[NENTRIES];

void

arp_cache_init(void)

{

  nentries = 0;

  victim = 0;

}

// returns non-negative index if found, else -1

static int

arp_cache_lookup(const struct ip_addr *ip)

{

  int i;

  for (i = 0; i < nentries; i++)

    if (cache[i].ip.addr == ip->addr)

      return i;

  return -1;

}

static int

arp_cache_alloc(void)

{

  if (nentries < NENTRIES)

    return nentries++;

  int i = victim;

  victim = (victim + 1) % NENTRIES;

  return i;

}

void 

arp_cache_update(const struct ip_addr *ip,

                 const eth_mac_addr_t *mac)

{

  int i = arp_cache_lookup(ip);

  if (i < 0){

    i = arp_cache_alloc();

    cache[i].ip = *ip;

    cache[i].mac = *mac;

  }

  else {

    cache[i].mac = *mac;

  }

}

bool

arp_cache_lookup_mac(const struct ip_addr *ip,

                     eth_mac_addr_t *mac)

{

  int i = arp_cache_lookup(ip);

  if (i < 0)

    return false;

  *mac = cache[i].mac;

  return true;

}