is an implementation of the DVMRP multicast routing protocol.
| inet.c (mrouted-4.3) | : | inet.c (mrouted-4.4) |
|---|
| | |
| skipping to change at line 225 | | skipping to change at line 225 |
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| * (ping.c) Status - | | * (ping.c) Status - |
| * Public Domain. Distribution Unlimited. | | * Public Domain. Distribution Unlimited. |
| * | | * |
| * I N _ C K S U M | | * I N _ C K S U M |
| * | | * |
| * Checksum routine for Internet Protocol family headers (C Version) | | * Checksum routine for Internet Protocol family headers (C Version) |
| * | | * |
| */ | | */ |
| int inet_cksum(uint16_t *addr, uint32_t len) | | int inet_cksum(uint16_t *addr, uint32_t len) |
| { | | { |
|
| int nleft = (int)len; | | int nleft = (int)len; |
| uint16_t *w = addr; | | uint16_t *w = addr; |
| uint16_t answer = 0; | | uint16_t answer = 0; |
| int32_t sum = 0; | | int32_t sum = 0; |
| | |
|
| /* | | /* |
| * Our algorithm is simple, using a 32 bit accumulator (sum), | | * Our algorithm is simple, using a 32 bit accumulator (sum), |
| * we add sequential 16 bit words to it, and at the end, fold | | * we add sequential 16 bit words to it, and at the end, fold |
| * back all the carry bits from the top 16 bits into the lower | | * back all the carry bits from the top 16 bits into the lower |
| * 16 bits. | | * 16 bits. |
| */ | | */ |
| while (nleft > 1) { | | while (nleft > 1) { |
| sum += *w++; | | sum += *w++; |
| nleft -= 2; | | nleft -= 2; |
| } | | } |
| | |
|
| /* mop up an odd byte, if necessary */ | | /* mop up an odd byte, if necessary */ |
| if (nleft == 1) { | | if (nleft == 1) { |
| *(uint8_t *) (&answer) = *(uint8_t *)w ; | | *(uint8_t *) (&answer) = *(uint8_t *)w ; |
| sum += answer; | | sum += answer; |
| } | | } |
| | |
|
| /* | | /* |
| * add back carry outs from top 16 bits to low 16 bits | | * add back carry outs from top 16 bits to low 16 bits |
| */ | | */ |
| sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ | | sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ |
| sum += (sum >> 16); /* add carry */ | | sum += (sum >> 16); /* add carry */ |
| answer = ~sum; /* truncate to 16 bits */ | | answer = ~sum; /* truncate to 16 bits */ |
| | |
|
| return answer; | | return answer; |
| } | | } |
| | |
| /** | | /** |
| * Local Variables: | | * Local Variables: |
| * indent-tabs-mode: t | | * indent-tabs-mode: t |
|
| * c-file-style: "ellemtel" | | * c-file-style: "cc-mode" |
| * c-basic-offset: 4 | | |
| * End: | | * End: |
| */ | | */ |
| | | |
| End of changes. 6 change blocks. |
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| 28 lines changed or deleted | | 27 lines changed or added |
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