hashing.c

wifi 无线网络路由协议OLSR linux下C代码

/*
 * The olsr.org Optimized Link-State Routing daemon(olsrd)
 * Copyright (c) 2004, Andreas T鴑nesen([e-mail])
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met:
 *
 * * Redistributions of source code must retain the above copyright 
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright 
 *   notice, this list of conditions and the following disclaimer in 
 *   the documentation and/or other materials provided with the 
 *   distribution.
 * * Neither the name of olsr.org, olsrd nor the names of its 
 *   contributors may be used to endorse or promote products derived 
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Visit http://www.olsr.org for more information.
 *
 * If you find this software useful feel free to make a donation
 * to the project. For more information see the website or contact
 * the copyright holders.
 *
 * $Id: hashing.c,v 1.16 2007/08/02 21:59:59 bernd67 Exp $
 */

#include "olsr_protocol.h"
#include "hashing.h"
#include "defs.h"

/**
 * Hashing function. Creates a key based on
 * an 32-bit address.
 * @param address the address to hash
 * @return the hash(a value in the 0-31 range)
 */
olsr_u32_t olsr_hashing(const union olsr_ip_addr * address)
{
    olsr_u32_t hash;
    if(olsr_cnf->ip_version == AF_INET) {
        /* IPv4 */  
        const olsr_u8_t * const v4x = (const olsr_u8_t *)&address->v4;
        hash = v4x[0] ^ v4x[1] ^ v4x[2] ^ v4x[3];
    } else {
        /* IPv6 */
        const char * const tmp = (const char *)&address->v6;
        hash = ntohl(*tmp);
    }
    return hash & HASHMASK;
}

/*
 * Local Variables:
 * mode: c
 * style: linux
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 */