1 | /**
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2 | * @file
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3 | * Incluse internet checksum functions.
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4 | *
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5 | */
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6 |
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7 | /*
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8 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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9 | * All rights reserved.
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10 | *
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11 | * Redistribution and use in source and binary forms, with or without modification,
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12 | * are permitted provided that the following conditions are met:
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13 | *
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14 | * 1. Redistributions of source code must retain the above copyright notice,
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15 | * this list of conditions and the following disclaimer.
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16 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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17 | * this list of conditions and the following disclaimer in the documentation
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18 | * and/or other materials provided with the distribution.
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19 | * 3. The name of the author may not be used to endorse or promote products
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20 | * derived from this software without specific prior written permission.
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21 | *
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22 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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23 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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24 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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25 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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26 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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27 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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30 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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31 | * OF SUCH DAMAGE.
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32 | *
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33 | * This file is part of the lwIP TCP/IP stack.
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34 | *
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35 | * Author: Adam Dunkels <adam@sics.se>
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36 | *
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37 | */
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38 |
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39 | #include "lwip/opt.h"
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40 |
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41 | #include "lwip/inet_chksum.h"
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42 | #include "lwip/def.h"
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43 |
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44 | #include <stddef.h>
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45 | #include <string.h>
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46 |
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47 | /* These are some reference implementations of the checksum algorithm, with the
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48 | * aim of being simple, correct and fully portable. Checksumming is the
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49 | * first thing you would want to optimize for your platform. If you create
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50 | * your own version, link it in and in your cc.h put:
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51 | *
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52 | * #define LWIP_CHKSUM <your_checksum_routine>
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53 | *
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54 | * Or you can select from the implementations below by defining
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55 | * LWIP_CHKSUM_ALGORITHM to 1, 2 or 3.
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56 | */
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57 |
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58 | #ifndef LWIP_CHKSUM
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59 | # define LWIP_CHKSUM lwip_standard_chksum
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60 | # ifndef LWIP_CHKSUM_ALGORITHM
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61 | # define LWIP_CHKSUM_ALGORITHM 2
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62 | # endif
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63 | #endif
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64 | /* If none set: */
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65 | #ifndef LWIP_CHKSUM_ALGORITHM
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66 | # define LWIP_CHKSUM_ALGORITHM 0
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67 | #endif
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68 |
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69 | #if (LWIP_CHKSUM_ALGORITHM == 1) /* Version #1 */
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70 | /**
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71 | * lwip checksum
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72 | *
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73 | * @param dataptr points to start of data to be summed at any boundary
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74 | * @param len length of data to be summed
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75 | * @return host order (!) lwip checksum (non-inverted Internet sum)
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76 | *
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77 | * @note accumulator size limits summable length to 64k
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78 | * @note host endianess is irrelevant (p3 RFC1071)
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79 | */
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80 | static u16_t
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81 | lwip_standard_chksum(void *dataptr, u16_t len)
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82 | {
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83 | u32_t acc;
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84 | u16_t src;
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85 | u8_t *octetptr;
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86 |
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87 | acc = 0;
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88 | /* dataptr may be at odd or even addresses */
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89 | octetptr = (u8_t*)dataptr;
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90 | while (len > 1) {
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91 | /* declare first octet as most significant
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92 | thus assume network order, ignoring host order */
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93 | src = (*octetptr) << 8;
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94 | octetptr++;
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95 | /* declare second octet as least significant */
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96 | src |= (*octetptr);
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97 | octetptr++;
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98 | acc += src;
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99 | len -= 2;
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100 | }
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101 | if (len > 0) {
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102 | /* accumulate remaining octet */
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103 | src = (*octetptr) << 8;
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104 | acc += src;
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105 | }
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106 | /* add deferred carry bits */
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107 | acc = (acc >> 16) + (acc & 0x0000ffffUL);
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108 | if ((acc & 0xffff0000UL) != 0) {
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109 | acc = (acc >> 16) + (acc & 0x0000ffffUL);
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110 | }
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111 | /* This maybe a little confusing: reorder sum using htons()
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112 | instead of ntohs() since it has a little less call overhead.
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113 | The caller must invert bits for Internet sum ! */
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114 | return htons((u16_t)acc);
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115 | }
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116 | #endif
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117 |
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118 | #if (LWIP_CHKSUM_ALGORITHM == 2) /* Alternative version #2 */
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119 | /*
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120 | * Curt McDowell
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121 | * Broadcom Corp.
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122 | * csm@broadcom.com
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123 | *
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124 | * IP checksum two bytes at a time with support for
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125 | * unaligned buffer.
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126 | * Works for len up to and including 0x20000.
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127 | * by Curt McDowell, Broadcom Corp. 12/08/2005
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128 | *
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129 | * @param dataptr points to start of data to be summed at any boundary
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130 | * @param len length of data to be summed
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131 | * @return host order (!) lwip checksum (non-inverted Internet sum)
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132 | */
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133 |
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134 | static u16_t
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135 | lwip_standard_chksum(void *dataptr, int len)
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136 | {
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137 | u8_t *pb = (u8_t *)dataptr;
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138 | u16_t *ps, t = 0;
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139 | u32_t sum = 0;
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140 | int odd = ((mem_ptr_t)pb & 1);
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141 |
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142 | /* Get aligned to u16_t */
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143 | if (odd && len > 0) {
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144 | ((u8_t *)&t)[1] = *pb++;
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145 | len--;
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146 | }
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147 |
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148 | /* Add the bulk of the data */
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149 | ps = (u16_t *)(void *)pb;
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150 | while (len > 1) {
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151 | sum += *ps++;
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152 | len -= 2;
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153 | }
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154 |
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155 | /* Consume left-over byte, if any */
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156 | if (len > 0) {
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157 | ((u8_t *)&t)[0] = *(u8_t *)ps;
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158 | }
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159 |
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160 | /* Add end bytes */
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161 | sum += t;
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162 |
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163 | /* Fold 32-bit sum to 16 bits
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164 | calling this twice is propably faster than if statements... */
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165 | sum = FOLD_U32T(sum);
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166 | sum = FOLD_U32T(sum);
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167 |
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168 | /* Swap if alignment was odd */
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169 | if (odd) {
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170 | sum = SWAP_BYTES_IN_WORD(sum);
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171 | }
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172 |
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173 | return (u16_t)sum;
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174 | }
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175 | #endif
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176 |
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177 | #if (LWIP_CHKSUM_ALGORITHM == 3) /* Alternative version #3 */
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178 | /**
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179 | * An optimized checksum routine. Basically, it uses loop-unrolling on
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180 | * the checksum loop, treating the head and tail bytes specially, whereas
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181 | * the inner loop acts on 8 bytes at a time.
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182 | *
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183 | * @arg start of buffer to be checksummed. May be an odd byte address.
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184 | * @len number of bytes in the buffer to be checksummed.
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185 | * @return host order (!) lwip checksum (non-inverted Internet sum)
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186 | *
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187 | * by Curt McDowell, Broadcom Corp. December 8th, 2005
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188 | */
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189 |
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190 | static u16_t
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191 | lwip_standard_chksum(void *dataptr, int len)
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192 | {
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193 | u8_t *pb = (u8_t *)dataptr;
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194 | u16_t *ps, t = 0;
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195 | u32_t *pl;
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196 | u32_t sum = 0, tmp;
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197 | /* starts at odd byte address? */
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198 | int odd = ((mem_ptr_t)pb & 1);
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199 |
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200 | if (odd && len > 0) {
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201 | ((u8_t *)&t)[1] = *pb++;
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202 | len--;
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203 | }
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204 |
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205 | ps = (u16_t *)pb;
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206 |
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207 | if (((mem_ptr_t)ps & 3) && len > 1) {
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208 | sum += *ps++;
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209 | len -= 2;
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210 | }
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211 |
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212 | pl = (u32_t *)ps;
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213 |
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214 | while (len > 7) {
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215 | tmp = sum + *pl++; /* ping */
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216 | if (tmp < sum) {
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217 | tmp++; /* add back carry */
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218 | }
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219 |
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220 | sum = tmp + *pl++; /* pong */
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221 | if (sum < tmp) {
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222 | sum++; /* add back carry */
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223 | }
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224 |
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225 | len -= 8;
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226 | }
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227 |
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228 | /* make room in upper bits */
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229 | sum = FOLD_U32T(sum);
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230 |
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231 | ps = (u16_t *)pl;
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232 |
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233 | /* 16-bit aligned word remaining? */
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234 | while (len > 1) {
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235 | sum += *ps++;
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236 | len -= 2;
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237 | }
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238 |
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239 | /* dangling tail byte remaining? */
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240 | if (len > 0) { /* include odd byte */
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241 | ((u8_t *)&t)[0] = *(u8_t *)ps;
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242 | }
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243 |
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244 | sum += t; /* add end bytes */
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245 |
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246 | /* Fold 32-bit sum to 16 bits
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247 | calling this twice is propably faster than if statements... */
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248 | sum = FOLD_U32T(sum);
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249 | sum = FOLD_U32T(sum);
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250 |
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251 | if (odd) {
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252 | sum = SWAP_BYTES_IN_WORD(sum);
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253 | }
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254 |
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255 | return (u16_t)sum;
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256 | }
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257 | #endif
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258 |
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259 | /* inet_chksum_pseudo:
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260 | *
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261 | * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
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262 | * IP addresses are expected to be in network byte order.
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263 | *
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264 | * @param p chain of pbufs over that a checksum should be calculated (ip data part)
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265 | * @param src source ip address (used for checksum of pseudo header)
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266 | * @param dst destination ip address (used for checksum of pseudo header)
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267 | * @param proto ip protocol (used for checksum of pseudo header)
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268 | * @param proto_len length of the ip data part (used for checksum of pseudo header)
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269 | * @return checksum (as u16_t) to be saved directly in the protocol header
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270 | */
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271 | u16_t
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272 | inet_chksum_pseudo(struct pbuf *p,
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273 | ip_addr_t *src, ip_addr_t *dest,
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274 | u8_t proto, u16_t proto_len)
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275 | {
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276 | u32_t acc;
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277 | u32_t addr;
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278 | struct pbuf *q;
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279 | u8_t swapped;
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280 |
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281 | acc = 0;
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282 | swapped = 0;
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283 | /* iterate through all pbuf in chain */
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284 | for(q = p; q != NULL; q = q->next) {
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285 | LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
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286 | (void *)q, (void *)q->next));
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287 | acc += LWIP_CHKSUM(q->payload, q->len);
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288 | /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
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289 | /* just executing this next line is probably faster that the if statement needed
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290 | to check whether we really need to execute it, and does no harm */
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291 | acc = FOLD_U32T(acc);
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292 | if (q->len % 2 != 0) {
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293 | swapped = 1 - swapped;
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294 | acc = SWAP_BYTES_IN_WORD(acc);
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295 | }
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296 | /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
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297 | }
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298 |
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299 | if (swapped) {
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300 | acc = SWAP_BYTES_IN_WORD(acc);
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301 | }
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302 | addr = ip4_addr_get_u32(src);
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303 | acc += (addr & 0xffffUL);
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304 | acc += ((addr >> 16) & 0xffffUL);
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305 | addr = ip4_addr_get_u32(dest);
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306 | acc += (addr & 0xffffUL);
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307 | acc += ((addr >> 16) & 0xffffUL);
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308 | acc += (u32_t)htons((u16_t)proto);
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309 | acc += (u32_t)htons(proto_len);
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310 |
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311 | /* Fold 32-bit sum to 16 bits
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312 | calling this twice is propably faster than if statements... */
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313 | acc = FOLD_U32T(acc);
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314 | acc = FOLD_U32T(acc);
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315 | LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
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316 | return (u16_t)~(acc & 0xffffUL);
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317 | }
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318 |
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319 | /* inet_chksum_pseudo:
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320 | *
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321 | * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
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322 | * IP addresses are expected to be in network byte order.
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323 | *
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324 | * @param p chain of pbufs over that a checksum should be calculated (ip data part)
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325 | * @param src source ip address (used for checksum of pseudo header)
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326 | * @param dst destination ip address (used for checksum of pseudo header)
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327 | * @param proto ip protocol (used for checksum of pseudo header)
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328 | * @param proto_len length of the ip data part (used for checksum of pseudo header)
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329 | * @return checksum (as u16_t) to be saved directly in the protocol header
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330 | */
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331 | u16_t
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332 | inet_chksum_pseudo_partial(struct pbuf *p,
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333 | ip_addr_t *src, ip_addr_t *dest,
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334 | u8_t proto, u16_t proto_len, u16_t chksum_len)
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335 | {
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336 | u32_t acc;
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337 | u32_t addr;
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338 | struct pbuf *q;
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339 | u8_t swapped;
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340 | u16_t chklen;
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341 |
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342 | acc = 0;
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343 | swapped = 0;
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344 | /* iterate through all pbuf in chain */
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345 | for(q = p; (q != NULL) && (chksum_len > 0); q = q->next) {
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346 | LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
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347 | (void *)q, (void *)q->next));
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348 | chklen = q->len;
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349 | if (chklen > chksum_len) {
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350 | chklen = chksum_len;
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351 | }
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352 | acc += LWIP_CHKSUM(q->payload, chklen);
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353 | chksum_len -= chklen;
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354 | LWIP_ASSERT("delete me", chksum_len < 0x7fff);
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355 | /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
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356 | /* fold the upper bit down */
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357 | acc = FOLD_U32T(acc);
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358 | if (q->len % 2 != 0) {
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359 | swapped = 1 - swapped;
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360 | acc = SWAP_BYTES_IN_WORD(acc);
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361 | }
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362 | /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
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363 | }
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364 |
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365 | if (swapped) {
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366 | acc = SWAP_BYTES_IN_WORD(acc);
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367 | }
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368 | addr = ip4_addr_get_u32(src);
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369 | acc += (addr & 0xffffUL);
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370 | acc += ((addr >> 16) & 0xffffUL);
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371 | addr = ip4_addr_get_u32(dest);
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372 | acc += (addr & 0xffffUL);
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373 | acc += ((addr >> 16) & 0xffffUL);
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374 | acc += (u32_t)htons((u16_t)proto);
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375 | acc += (u32_t)htons(proto_len);
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376 |
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377 | /* Fold 32-bit sum to 16 bits
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378 | calling this twice is propably faster than if statements... */
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379 | acc = FOLD_U32T(acc);
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380 | acc = FOLD_U32T(acc);
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381 | LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
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382 | return (u16_t)~(acc & 0xffffUL);
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383 | }
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384 |
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385 | /* inet_chksum:
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386 | *
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387 | * Calculates the Internet checksum over a portion of memory. Used primarily for IP
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388 | * and ICMP.
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389 | *
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390 | * @param dataptr start of the buffer to calculate the checksum (no alignment needed)
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391 | * @param len length of the buffer to calculate the checksum
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392 | * @return checksum (as u16_t) to be saved directly in the protocol header
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393 | */
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394 |
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395 | u16_t
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396 | inet_chksum(void *dataptr, u16_t len)
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397 | {
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398 | return ~LWIP_CHKSUM(dataptr, len);
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399 | }
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400 |
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401 | /**
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402 | * Calculate a checksum over a chain of pbufs (without pseudo-header, much like
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403 | * inet_chksum only pbufs are used).
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404 | *
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405 | * @param p pbuf chain over that the checksum should be calculated
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406 | * @return checksum (as u16_t) to be saved directly in the protocol header
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407 | */
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408 | u16_t
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409 | inet_chksum_pbuf(struct pbuf *p)
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410 | {
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411 | u32_t acc;
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412 | struct pbuf *q;
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413 | u8_t swapped;
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414 |
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415 | acc = 0;
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416 | swapped = 0;
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417 | for(q = p; q != NULL; q = q->next) {
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418 | acc += LWIP_CHKSUM(q->payload, q->len);
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419 | acc = FOLD_U32T(acc);
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420 | if (q->len % 2 != 0) {
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421 | swapped = 1 - swapped;
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422 | acc = SWAP_BYTES_IN_WORD(acc);
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423 | }
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424 | }
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425 |
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426 | if (swapped) {
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427 | acc = SWAP_BYTES_IN_WORD(acc);
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428 | }
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429 | return (u16_t)~(acc & 0xffffUL);
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430 | }
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431 |
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432 | /* These are some implementations for LWIP_CHKSUM_COPY, which copies data
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433 | * like MEMCPY but generates a checksum at the same time. Since this is a
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434 | * performance-sensitive function, you might want to create your own version
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435 | * in assembly targeted at your hardware by defining it in lwipopts.h:
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436 | * #define LWIP_CHKSUM_COPY(dst, src, len) your_chksum_copy(dst, src, len)
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437 | */
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438 |
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439 | #if (LWIP_CHKSUM_COPY_ALGORITHM == 1) /* Version #1 */
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440 | /** Safe but slow: first call MEMCPY, then call LWIP_CHKSUM.
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441 | * For architectures with big caches, data might still be in cache when
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442 | * generating the checksum after copying.
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443 | */
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444 | u16_t
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445 | lwip_chksum_copy(void *dst, const void *src, u16_t len)
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446 | {
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447 | MEMCPY(dst, src, len);
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448 | return LWIP_CHKSUM(dst, len);
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449 | }
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450 | #endif /* (LWIP_CHKSUM_COPY_ALGORITHM == 1) */
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