求CRC算法的代码实现

tanyayun

求CRC算法的代码实现，包括头文件哦

O(∩_∩)O谢谢
网上搜了一些，可是运行时都出错哎

bruceteen

这个给你参考一下
http://blog.vckbase.com/bruceteen/archive/2011/01/10/52352.html

huxk

nginx裏面有。

yulihua49

求CRC算法的代码实现，包括头文件哦

O(∩_∩)O谢谢
网上搜了一些，可是运行时都出错哎
tanyayun 发表于 2011-12-08 11:06

crc32.h:

1. /*
   
2. * Author: Tatu Ylonen <ylo@cs.hut.fi>
   
3. * Copyright (c) 1992 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   
4. *                    All rights reserved
   
5. * Functions for computing 32-bit CRC.
   
6. *
   
7. * As far as I am concerned, the code I have written for this software
   
8. * can be used freely for any purpose.  Any derived versions of this
   
9. * software must be clearly marked as such, and if the derived work is
   
10. * incompatible with the protocol description in the RFC file, it must be
    
11. * called by a name other than "ssh" or "Secure Shell".
    
12. */
    
13. 
    
14. /* RCSID("$OpenBSD: crc32.h,v 1.10 2001/03/02 18:54:31 deraadt Exp $"); */
    
15. 
    
16. #ifndef CRC32_H
    
17. #define CRC32_H
    
18. 
    
19. #include <sys/types.h>
    
20. /*
    
21. * This computes a 32 bit CRC of the data in the buffer, and returns the CRC.
    
22. * The polynomial used is 0xedb88320.
    
23. */
    
24. #ifdef __cplusplus
    
25. extern "C" {
    
26. #endif
    
27. 
    
28. u_int ssh_crc32(const u_char *buf, u_int len);
    
29. 
    
30. #ifdef __cplusplus
    
31. }
    
32. #endif
    
33. #endif                          /* CRC32_H */
    

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yulihua49

crc32.h:
yulihua49 发表于 2011-12-08 13:41

    crc32.c:

1. #include "crc32.h"
   
2. 
   
3. static const u_int crc32_tab[] = {
   
4.         0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
   
5.         0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
   
6.         0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
   
7.         0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
   
8.         0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
   
9.         0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
   
10.         0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
    
11.         0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
    
12.         0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
    
13.         0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
    
14.         0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
    
15.         0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
    
16.         0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
    
17.         0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
    
18.         0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
    
19.         0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
    
20.         0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
    
21.         0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
    
22.         0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
    
23.         0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
    
24.         0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
    
25.         0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
    
26.         0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
    
27.         0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
    
28.         0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
    
29.         0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
    
30.         0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
    
31.         0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
    
32.         0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
    
33.         0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
    
34.         0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
    
35.         0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
    
36.         0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
    
37.         0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
    
38.         0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
    
39.         0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
    
40.         0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
    
41.         0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
    
42.         0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
    
43.         0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
    
44.         0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
    
45.         0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
    
46.         0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
    
47.         0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
    
48.         0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
    
49.         0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
    
50.         0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
    
51.         0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
    
52.         0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
    
53.         0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
    
54.         0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
    
55.         0x2d02ef8dL
    
56. };
    
57. 
    
58. /* Return a 32-bit CRC of the contents of the buffer. */
    
59. 
    
60. u_int
    
61. ssh_crc32(const u_char *s, u_int len)
    
62. {
    
63.         u_int i;
    
64.         u_int crc32val;
    
65. 
    
66.         crc32val = 0;
    
67.         for (i = 0;  i < len;  i ++) {
    
68.                 crc32val = crc32_tab[(crc32val ^ s[i]) & 0xff] ^ (crc32val >> 8);
    
69.         }
    
70.         return crc32val;
    
71. }
    

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tanyayun

回复 2# bruceteen


   我运行的得到的值怎么不在表 crc16tbl_[256]中呀？而且得出的是59555（其中一个例子），好像位数不对吧？

tanyayun

回复 5# yulihua49


   您好，谢谢帮助，可是我运行的还是出错呀，在您那运行正常吗？

yulihua49

回复  yulihua49


   您好，谢谢帮助，可是我运行的还是出错呀，在您那运行正常吗？
tanyayun 发表于 2011-12-08 15:01

    使用多年，没错。

yulihua49

回复  bruceteen


   我运行的得到的值怎么不在表 crc16tbl_[256]中呀？而且得出的是59555（其中一个例 ...
tanyayun 发表于 2011-12-08 14:54

当然不在。你知道CRC干什么用的吗？

jeung

1. #include<iostream>
   
2. using namespace std;
   
3. 
   
4. const int        N=3;
   
5. const int        BITSIZE=64;
   
6. const int        P[N+1]={1,1,0,1};        //P为生成多项式
   
7. 
   
8. void main(void)
   
9. {
   
10.         int        bit[BITSIZE]={0},len,i,j;
    
11.         char        ch;
    
12.         cout<<"Input the bit size:";
    
13.         cin>>len;
    
14.         cout<<"Input the bit code:";
    
15.         for(i=0;i<len;i++){
    
16.                 cin>>ch;
    
17.                 bit[i]=ch-'0';
    
18.         }
    
19.         for(i=0;i<len;i++){
    
20.                 if(bit[i]==0)continue;
    
21.                 for(j=1;j<=N;j++)
    
22.                         bit[i+j]=(bit[i+j]+P[j]==1);
    
23.         }
    
24.         cout<<"The FCS is:";
    
25.         for(i=len;i<len+N;i++)
    
26.                 cout<<bit[i];
    
27.         cin>>len;
    
28. }

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回复 1# tanyayun 哈哈，我当年上计算机网络这门课的实验作业