CRC8检验算法（C语言实现）_crc8校验算法c语言

初始值：0xFF

多项式 ：X^8+X^2+X^1+1,即0x31

结果异或值：0x00

直接计算法：

#define CRC8_POLYNOMIAL 0x31
/*
*
 * CRC-8 formula from page 14 of SHT spec pdf
 *
 * Test data 0xBE, 0xEF should yield 0x92
 *
 * Initialization data 0xFF
 * Polynomial 0x31 (x8 + x5 +x4 +1)
 * Final XOR 0x00
 */
uint8_t CheckCrc8(uint8_t *data, uint8_t nbrOfBytes, uint8_t checksum){ 
    uint8_t crc8 = 0xFF, bit = 0;
    while(nbrOfBytes--){
        crc8 ^= *data++;
        for (bit = 8; bit > 0; --bit) {
            crc8 = ( crc8 & 0x80 )
              ? (crc8 << 1) ^ CRC8_POLYNOMIAL
              : (crc8 << 1);
        }
    }
    return crc8 != checksum;
}

查表法：

// 按照多项式 X^8+X^2+X^1+1 生成。
static const unsigned int crc8Table[256] =
{
  0x00, 0x31, 0x62, 0x53, 0xc4, 0xf5, 0xa6, 0x97, 0xb9, 0x88, 0xdb, 0xea, 0x7d, 0x4c, 0x1f, 0x2e, 
  0x43, 0x72, 0x21, 0x10, 0x87, 0xb6, 0xe5, 0xd4, 0xfa, 0xcb, 0x98, 0xa9, 0x3e, 0x0f, 0x5c, 0x6d, 
  0x86, 0xb7, 0xe4, 0xd5, 0x42, 0x73, 0x20, 0x11, 0x3f, 0x0e, 0x5d, 0x6c, 0xfb, 0xca, 0x99, 0xa8, 
  0xc5, 0xf4, 0xa7, 0x96, 0x01, 0x30, 0x63, 0x52, 0x7c, 0x4d, 0x1e, 0x2f, 0xb8, 0x89, 0xda, 0xeb, 
  0x3d, 0x0c, 0x5f, 0x6e, 0xf9, 0xc8, 0x9b, 0xaa, 0x84, 0xb5, 0xe6, 0xd7, 0x40, 0x71, 0x22, 0x13, 
  0x7e, 0x4f, 0x1c, 0x2d, 0xba, 0x8b, 0xd8, 0xe9, 0xc7, 0xf6, 0xa5, 0x94, 0x03, 0x32, 0x61, 0x50, 
  0xbb, 0x8a, 0xd9, 0xe8, 0x7f, 0x4e, 0x1d, 0x2c, 0x02, 0x33, 0x60, 0x51, 0xc6, 0xf7, 0xa4, 0x95, 
  0xf8, 0xc9, 0x9a, 0xab, 0x3c, 0x0d, 0x5e, 0x6f, 0x41, 0x70, 0x23, 0x12, 0x85, 0xb4, 0xe7, 0xd6, 
  0x7a, 0x4b, 0x18, 0x29, 0xbe, 0x8f, 0xdc, 0xed, 0xc3, 0xf2, 0xa1, 0x90, 0x07, 0x36, 0x65, 0x54, 
  0x39, 0x08, 0x5b, 0x6a, 0xfd, 0xcc, 0x9f, 0xae, 0x80, 0xb1, 0xe2, 0xd3, 0x44, 0x75, 0x26, 0x17, 
  0xfc, 0xcd, 0x9e, 0xaf, 0x38, 0x09, 0x5a, 0x6b, 0x45, 0x74, 0x27, 0x16, 0x81, 0xb0, 0xe3, 0xd2, 
  0xbf, 0x8e, 0xdd, 0xec, 0x7b, 0x4a, 0x19, 0x28, 0x06, 0x37, 0x64, 0x55, 0xc2, 0xf3, 0xa0, 0x91, 
  0x47, 0x76, 0x25, 0x14, 0x83, 0xb2, 0xe1, 0xd0, 0xfe, 0xcf, 0x9c, 0xad, 0x3a, 0x0b, 0x58, 0x69, 
  0x04, 0x35, 0x66, 0x57, 0xc0, 0xf1, 0xa2, 0x93, 0xbd, 0x8c, 0xdf, 0xee, 0x79, 0x48, 0x1b, 0x2a, 
  0xc1, 0xf0, 0xa3, 0x92, 0x05, 0x34, 0x67, 0x56, 0x78, 0x49, 0x1a, 0x2b, 0xbc, 0x8d, 0xde, 0xef, 
  0x82, 0xb3, 0xe0, 0xd1, 0x46, 0x77, 0x24, 0x15, 0x3b, 0x0a, 0x59, 0x68, 0xff, 0xce, 0x9d, 0xac, 
 
};
 
// 查表法计算CRC值
uint8_t CalTableCrc8(uint8_t *data, uint8_t nbrOfBytes, uint8_t checksum){
	uint8_t crc8 = 0xff;
 
    while (nbrOfBytes --){
        crc8 = crc8Table[crc8 ^ *data++];
    }
  return crc8 != checksum;
}
 
uint8_t cal_table_high_first(uint8_t value)
{
    uint8_t i, crc;
 
    crc = value;
    for (i=8; i>0; --i){ 
      crc = ( crc & 0x80 )
        ? (crc << 1) ^ CRC8_POLYNOMIAL
        : (crc << 1);
    } 
 
    return crc;
}
 
void  create_crc_table(void)
{
    uint16_t i;
    uint8_t j;
 
    for (i=0; i<=0xFF; i++)
    {
        if (0 == (i%16))
            printf("\n");
 
        j = i&0xFF;
            printf("0x%.2x, ", cal_table_high_first (j));  /*依次计算每个字节的crc校验值*/
    }
}