（65）CRC32校验C语言版本

2024-10-07 04:38:36

#include<iostream>
# include <stdio.h>
# include <string.h>
typedef unsigned int uint ;
uint POLYNOMIAL = 0xEDB88320 ;
int have_table = 0 ;
uint table[256] ;
void make_table()
{
int i, j, crc ;
have_table = 1 ;
for (i = 0 ; i < 256 ; i++)
for (j = 0, table[i] = i ; j < 8 ; j++)
table[i] = (table[i]>>1)^((table[i]&1)?POLYNOMIAL:0) ;
}
uint crc32(uint crc, char *buff, int len)
{
if (!have_table) make_table() ;
crc = ~crc;
for (int i = 0; i < len; i++)
crc = (crc >> 8) ^ table[(crc ^ buff[i]) & 0xff];
return ~crc;
}
int main ()
{
char s[] = "676547657567";
printf("%08Xh\n", crc32(0, s, strlen(s)));
system("pause");
return 0 ;
}

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