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ng_inet_csum: fix double-wrap around of carry

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This commit is contained in:
Martine Lenders 2015-07-01 18:19:22 +02:00
parent 6ce23a42f5
commit ad6c02b349
1 changed files with 6 additions and 3 deletions
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9
sys/net/crosslayer/ng_inet_csum/ng_inet_csum.c
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@ -43,11 +43,14 @@ uint16_t ng_inet_csum(uint16_t sum, const uint8_t *buf, uint16_t len)
csum += (*buf << 8); /* add last byte as top half of 16-byte word */ csum += (*buf << 8); /* add last byte as top half of 16-byte word */
} }
csum += csum >> 16; while (csum >> 16) {
uint16_t carry = csum >> 16;
csum = (csum & 0xffff) + carry;
}
DEBUG("inet_sum: new sum = 0x%04" PRIx32 "\n", csum & 0xffff); DEBUG("inet_sum: new sum = 0x%04" PRIx32 "\n", csum);
return (csum & 0xffff); return csum;
} }
/** @} */ /** @} */