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:文章来源:https://www.toymoban.com/news/detail-830161.html
#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:文章来源地址https://www.toymoban.com/news/detail-830161.html
// 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*/
}
}
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