nes-proj/cpu/msp430/uip-ipchksum.c
2007-04-04 11:53:07 +00:00

70 lines
2.9 KiB
C

/*
* Copyright (c) 2007, Swedish Institute of Computer Science.
* 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. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
*
* This file is part of the Contiki operating system.
*
* $Id: uip-ipchksum.c,v 1.4 2007/04/04 11:53:07 bg- Exp $
*/
/**
* \file
* uIP checksum calculation for MSP430
*/
#include "net/uip.h"
#define asmv(arg) __asm__ __volatile__(arg)
/*---------------------------------------------------------------------------*/
#ifdef UIP_ARCH_IPCHKSUM
u16_t
uip_ipchksum(void)
{
/* Assumes proper alignement of uip_buf. */
u16_t *p = (u16_t *)&uip_buf[UIP_LLH_LEN];
register u16_t sum;
sum = p[0];
asmv("add %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[1]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[2]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[3]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[4]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[5]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[6]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[7]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[8]));
asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[9]));
/* Finally, add the remaining carry bit. */
asmv("addc #0, %[sum]": [sum] "+r" (sum));
/* Return sum in network byte order. */
return (sum == 0) ? 0xffff : sum;
}
#endif
/*---------------------------------------------------------------------------*/