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27 * This file is part of the lwIP TCP/IP stack.
29 * Author: Adam Dunkels <adam@sics.se>
36 * Functions common to all TCP/IP modules, such as the Internet checksum and the
37 * byte order functions.
45 #include "lwip/inet.h"
51 * Sums up all 16 bit words in a memory portion. Also includes any odd byte.
52 * This function is used by the other checksum functions.
54 * For now, this is not optimized. Must be optimized for the particular processor
55 * arcitecture on which it is to run. Preferebly coded in assembler.
59 chksum(void *dataptr, u16_t len)
61 u16_t *sdataptr = dataptr;
65 for(acc = 0; len > 1; len -= 2) {
69 /* add up any odd byte */
71 acc += htons((u16_t)(*(u8_t *)dataptr) << 8);
78 /* inet_chksum_pseudo:
80 * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
84 inet_chksum_pseudo(struct pbuf *p,
85 struct ip_addr *src, struct ip_addr *dest,
86 u8_t proto, u32_t proto_len)
94 for(q = p; q != NULL; q = q->next) {
95 acc += chksum(q->payload, q->len);
97 acc = (acc & 0xffff) + (acc >> 16);
99 if (q->len % 2 != 0) {
100 swapped = 1 - swapped;
101 acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
106 acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
109 for(i = 0; i < 8; i++) {
110 acc += ((u16_t *)src->addr)[i] & 0xffff;
111 acc += ((u16_t *)dest->addr)[i] & 0xffff;
113 acc = (acc & 0xffff) + (acc >> 16);
116 acc += (u16_t)htons((u16_t)proto);
117 acc += ((u16_t *)&proto_len)[0] & 0xffff;
118 acc += ((u16_t *)&proto_len)[1] & 0xffff;
121 acc = (acc & 0xffff) + (acc >> 16);
123 return ~(acc & 0xffff);
128 * Calculates the Internet checksum over a portion of memory. Used primarely for IP
133 inet_chksum(void *dataptr, u16_t len)
137 acc = chksum(dataptr, len);
138 sum = (acc & 0xffff) + (acc >> 16);
140 return ~(sum & 0xffff);
144 inet_chksum_pbuf(struct pbuf *p)
152 for(q = p; q != NULL; q = q->next) {
153 acc += chksum(q->payload, q->len);
155 acc = (acc & 0xffff) + (acc >> 16);
157 if (q->len % 2 != 0) {
158 swapped = 1 - swapped;
159 acc = (acc & 0xff << 8) | (acc & 0xff00 >> 8);
164 acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
166 return ~(acc & 0xffff);