source: rtems/cpukit/libnetworking/machine/in_cksum.h @ 3f098aed

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
 *
 *      from tahoe:     in_cksum.c      1.2     86/01/05
 *      from:           @(#)in_cksum.c  1.3 (Berkeley) 1/19/91
 *      from: Id: in_cksum.c,v 1.8 1995/12/03 18:35:19 bde Exp
 *      $Id$
 */

#ifndef _MACHINE_IN_CKSUM_H_
#define _MACHINE_IN_CKSUM_H_    1

#include <sys/cdefs.h>

/*
 * It it useful to have an Internet checksum routine which is inlineable
 * and optimized specifically for the task of computing IP header checksums
 * in the normal case (where there are no options and the header length is
 * therefore always exactly five 32-bit words.
 */
#if (defined(__GNUC__) && defined(__i386__))
static __inline u_int
in_cksum_hdr(const struct ip *ip)
{
        register u_int sum = 0;
                    
#define ADD(n)  __asm("addl " #n "(%2), %0" : "=r" (sum) : "0" (sum), "r" (ip))
#define ADDC(n) __asm("adcl " #n "(%2), %0" : "=r" (sum) : "0" (sum), "r" (ip))
#define MOP     __asm("adcl         $0, %0" : "=r" (sum) : "0" (sum))

        ADD(0);
        ADDC(4);
        ADDC(8);
        ADDC(12);
        ADDC(16);
        MOP;
        sum = (sum & 0xffff) + (sum >> 16);
        if (sum > 0xffff)
                sum -= 0xffff;

        return ~sum & 0xffff;
}

static __inline void
in_cksum_update(struct ip *ip)
{
        int __tmpsum;
        __tmpsum = (int)ntohs(ip->ip_sum) + 256;
        ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16));
}

#elif (defined(__GNUC__) && (defined(__mc68000__) || defined(__m68k__)))

static __inline__ u_int
in_cksum_hdr(const struct ip *ip)
{
        register u_int *ap = (u_int *)ip;
        register u_int sum = *ap++;
        register u_int tmp;
                    
        __asm__("addl  %2@+,%0\n\t"
                "movel %2@+,%1\n\t"
                "addxl %1,%0\n\t"
                "movel %2@+,%1\n\t"
                "addxl %1,%0\n\t"
                "movel %2@,%1\n\t"
                "addxl %1,%0\n\t"
                "moveq #0,%1\n\t"
                "addxl %1,%0\n" :
                "=d" (sum), "=d" (tmp), "=a" (ap) :
                "0" (sum), "2" (ap));
        sum = (sum & 0xffff) + (sum >> 16);
        if (sum > 0xffff)
                sum -= 0xffff;
        return ~sum & 0xffff;
}

#else
u_int in_cksum_hdr __P((const struct ip *));
#define in_cksum_update(ip) \
        do { \
                int __tmpsum; \
                __tmpsum = (int)ntohs(ip->ip_sum) + 256; \
                ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16)); \
        } while(0)

#endif

#endif /* _MACHINE_IN_CKSUM_H_ */