2 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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6 * are permitted provided that the following conditions are met:
8 * 1. Redistributions of source code must retain the above copyright notice,
9 * this list of conditions and the following disclaimer.
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11 * this list of conditions and the following disclaimer in the documentation
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14 * derived from this software without specific prior written permission.
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23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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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);