在高速和大量数据传输时，为了保证数据的准确性，通常需要添加CRC效验，网上关于CRC-16的算法很多，8位的很少，经过长时间搜索和实验之后，得到两种可靠的算法：
1.
unsigned char Crc8Value(unsigned char crc,unsigned char dat)
{
unsigned char loop;
unsigned char crcTemp;
BOOL bitTemp;
for(loop=0; loop<8; loop++)
{
crcTemp = crc;
crc >>=1;
bitTemp = (crcTemp&0x01)^(dat&0x01);
if(bitTemp)
{
if(crcTemp&0x08) ClrBit(crc,2);
else SetBit(crc,2);
if(crcTemp&0x10) ClrBit(crc,3);
else SetBit(crc,3);
crc |= 0x80;
}
else
{
if(crcTemp&0x08) SetBit(crc,2);
else ClrBit(crc,2);
if(crcTemp&0x10) SetBit(crc,3);
else ClrBit(crc,3);
crc &= 0x7f;
}
dat >>= 1;
}
return crc;
}
2.这个最简单。
unsigned char CRC8(unsigned char crc, unsigned char data)
{
int j;
crc = crc ^data;
for (j = 0; j < 8; j++)
{
if ((crc & 0x01) != 0) crc = (crc >> 1) ^ 0x8c;
else crc = crc >> 1;
}
return crc;
}
测试程序：
void main(void)
{
unsigned char data[9] = {0x30,0xd8,0x53,0x5a,0x00,0x00,0x00,0x66,0x3F};
unsigned char crc=0;
for(int i=0;i<8;i++)
{
//crc=Crc8Value(crc,data[i]);
crc=CRC8(crc,data[i]);
}
printf("CRC = %d",crc);
}
/*
* CRC8.c
*
* Created on: Apr 30, 2014
* Author: conan
*/
/* 8-bit CRC with polynomial x^8+x^6+x^3+x^2+1, 0x14D.
Chosen based on Koopman, et al. (0xA6 in his notation = 0x14D >> 1):
*/
#include "stdafx.h"
static unsigned char crc8_table[] = {
0x00, 0x3e, 0x7c, 0x42, 0xf8, 0xc6, 0x84, 0xba, 0x95, 0xab, 0xe9, 0xd7,
0x6d, 0x53, 0x11, 0x2f, 0x4f, 0x71, 0x33, 0x0d, 0xb7, 0x89, 0xcb, 0xf5,
0xda, 0xe4, 0xa6, 0x98, 0x22, 0x1c, 0x5e, 0x60, 0x9e, 0xa0, 0xe2, 0xdc,
0x66, 0x58, 0x1a, 0x24, 0x0b, 0x35, 0x77, 0x49, 0xf3, 0xcd, 0x8f, 0xb1,
0xd1, 0xef, 0xad, 0x93, 0x29, 0x17, 0x55, 0x6b, 0x44, 0x7a, 0x38, 0x06,
0xbc, 0x82, 0xc0, 0xfe, 0x59, 0x67, 0x25, 0x1b, 0xa1, 0x9f, 0xdd, 0xe3,
0xcc, 0xf2, 0xb0, 0x8e, 0x34, 0x0a, 0x48, 0x76, 0x16, 0x28, 0x6a, 0x54,
0xee, 0xd0, 0x92, 0xac, 0x83, 0xbd, 0xff, 0xc1, 0x7b, 0x45, 0x07, 0x39,
0xc7, 0xf9, 0xbb, 0x85, 0x3f, 0x01, 0x43, 0x7d, 0x52, 0x6c, 0x2e, 0x10,
0xaa, 0x94, 0xd6, 0xe8, 0x88, 0xb6, 0xf4, 0xca, 0x70, 0x4e, 0x0c, 0x32,
0x1d, 0x23, 0x61, 0x5f, 0xe5, 0xdb, 0x99, 0xa7, 0xb2, 0x8c, 0xce, 0xf0,
0x4a, 0x74, 0x36, 0x08, 0x27, 0x19, 0x5b, 0x65, 0xdf, 0xe1, 0xa3, 0x9d,
0xfd, 0xc3, 0x81, 0xbf, 0x05, 0x3b, 0x79, 0x47, 0x68, 0x56, 0x14, 0x2a,
0x90, 0xae, 0xec, 0xd2, 0x2c, 0x12, 0x50, 0x6e, 0xd4, 0xea, 0xa8, 0x96,
0xb9, 0x87, 0xc5, 0xfb, 0x41, 0x7f, 0x3d, 0x03, 0x63, 0x5d, 0x1f, 0x21,
0x9b, 0xa5, 0xe7, 0xd9, 0xf6, 0xc8, 0x8a, 0xb4, 0x0e, 0x30, 0x72, 0x4c,
0xeb, 0xd5, 0x97, 0xa9, 0x13, 0x2d, 0x6f, 0x51, 0x7e, 0x40, 0x02, 0x3c,
0x86, 0xb8, 0xfa, 0xc4, 0xa4, 0x9a, 0xd8, 0xe6, 0x5c, 0x62, 0x20, 0x1e,
0x31, 0x0f, 0x4d, 0x73, 0xc9, 0xf7, 0xb5, 0x8b, 0x75, 0x4b, 0x09, 0x37,
0x8d, 0xb3, 0xf1, 0xcf, 0xe0, 0xde, 0x9c, 0xa2, 0x18, 0x26, 0x64, 0x5a,
0x3a, 0x04, 0x46, 0x78, 0xc2, 0xfc, 0xbe, 0x80, 0xaf, 0x91, 0xd3, 0xed,
0x57, 0x69, 0x2b, 0x15};
unsigned char crc8(unsigned char *data, int len)
{
unsigned char crc = 0;
unsigned char *end;
if (len == 0)
return crc;
crc ^= 0xff;
end = data + len;
do {
crc = crc8_table[crc ^ *data++];
} while (data < end);
return crc ^ 0xff;
}
/* this was used to generate the table and to test the table-version
#define POLY 0xB2
unsigned crc8_slow(unsigned crc, unsigned char *data, size_t len)
{
unsigned char *end;
if (len == 0)
return crc;
crc ^= 0xff;
end = data + len;
do {
crc ^= *data++;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
} while (data < end);
return crc ^ 0xff;
}
*/