2 * Checksum routine for Internet Protocol family headers (C Version)
4 * Licensed under GPLv2, see file LICENSE in this source tree.
9 uint16_t FAST_FUNC inet_cksum(uint16_t *addr, int nleft)
12 * Our algorithm is simple, using a 32 bit accumulator,
13 * we add sequential 16 bit words to it, and at the end, fold
14 * back all the carry bits from the top 16 bits into the lower
23 /* Mop up an odd byte, if necessary */
26 sum += *(uint8_t*)addr;
28 sum += *(uint8_t*)addr << 8;
31 /* Add back carry outs from top 16 bits to low 16 bits */
32 sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
33 sum += (sum >> 16); /* add carry */
35 return (uint16_t)~sum;