70 lines
2.9 KiB
C
70 lines
2.9 KiB
C
/*
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* Copyright (c) 2007, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* $Id: uip-ipchksum.c,v 1.4 2007/04/04 11:53:07 bg- Exp $
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*/
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/**
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* \file
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* uIP checksum calculation for MSP430
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*/
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#include "net/uip.h"
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#define asmv(arg) __asm__ __volatile__(arg)
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/*---------------------------------------------------------------------------*/
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#ifdef UIP_ARCH_IPCHKSUM
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u16_t
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uip_ipchksum(void)
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{
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/* Assumes proper alignement of uip_buf. */
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u16_t *p = (u16_t *)&uip_buf[UIP_LLH_LEN];
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register u16_t sum;
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sum = p[0];
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asmv("add %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[1]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[2]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[3]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[4]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[5]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[6]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[7]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[8]));
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asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[9]));
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/* Finally, add the remaining carry bit. */
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asmv("addc #0, %[sum]": [sum] "+r" (sum));
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/* Return sum in network byte order. */
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return (sum == 0) ? 0xffff : sum;
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}
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#endif
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/*---------------------------------------------------------------------------*/
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