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uIP checksum calculation for MSP430

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adamdunkels 2007-03-15 21:38:46 +00:00
parent c1df2e6df8
commit 36c17d22d0
1 changed files with 28 additions and 0 deletions
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cpu/msp430/uip-ipchksum.c Normal file
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/*---------------------------------------------------------------------------*/
#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
/*---------------------------------------------------------------------------*/