（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] ;
8. void make_table()
9. {
10. int i, j, crc ;
11. have_table = 1 ;
12. for (i = 0 ; i < 256 ; i++)
13. for (j = 0, table[i] = i ; j < 8 ; j++)
14. table[i] = (table[i]>>1)^((table[i]&1)?POLYNOMIAL:0) ;
15. }
16. uint crc32(uint crc, char *buff, int len)
17. {
18. if (!have_table) make_table() ;
19. crc = ~crc;
20. for (int i = 0; i < len; i++)
21. crc = (crc >> 8) ^ table[(crc ^ buff[i]) & 0xff];
22. return ~crc;
23. }
24. int main ()
25. {
26. char s[] = "676547657567";
27. printf("%08Xh\n", crc32(0, s, strlen(s)));
28. system("pause");
29. return 0 ;
30. }