（65）CRC32校验C语言版本

1. #include<iostream>
2. # include <stdio.h>
3. # include <string.h>
4. typedef unsigned int uint ;
5. uint POLYNOMIAL = 0xEDB88320 ;
6. int have_table = 0 ;
7. uint table[256] ;
9. void make_table()
10. {
11. int i, j, crc ;
12. have_table = 1 ;
13. for (i = 0 ; i < 256 ; i++)
14. for (j = 0, table[i] = i ; j < 8 ; j++)
15. table[i] = (table[i]>>1)^((table[i]&1)?POLYNOMIAL:0) ;
16. }
18. uint crc32(uint crc, char *buff, int len)
19. {
20. if (!have_table) make_table() ;
21. crc = ~crc;
22. for (int i = 0; i < len; i++)
23. crc = (crc >> 8) ^ table[(crc ^ buff[i]) & 0xff];
24. return ~crc;
25. }
27. int main ()
28. {
29. char s[] = "676547657567";
30. printf("%08Xh ", crc32(0, s, strlen(s)));
31. system("pause");
32. return 0 ;
33. }