CDT协议中crc8校验算法

本文计算方法均参考他人文档:

算法1:

void crc8_CDT_init(uint32_t poly) {
  uint16_t crc;
  for (int i = 0, j; i < 256; i++) {
    crc = 0x00FF & i;

    for (j = 0; j < 8; j++) {
      crc =
          0x00FF & (((crc & 0x80) == 0x80) ? (poly ^ (crc << 1)) : (crc << 1));
    }
    table[i] = crc;
    if ((i + 1) % 8 == 0) {
      printf(" 0x%02x\n", crc);
    } else {
      printf(" 0x%02x", crc);
    }
  }
}

uint8_t crc8_CDT(uint8_t crc, void* input, int len) {
  int i;
  uint8_t index;
  uint8_t* p;
  p = (uint8_t*)input;
  for (i = 0; i < len; i++) {
    index = (*p ^ crc);
    crc = table[index];
    p++;
  }
  return crc ^ 0xFF;
}

算法2:

unsigned char CRC_8_bit(unsigned char* pData, int count) {
  unsigned char CRC = 0x00;
  unsigned char cData;
  for (int n = 0; n <= count; ++n) {
    // 处理的字节
    cData = 0;
    if (n < count)
      cData = pData[n];
    else
      cData = 0;  // 数据结束

    for (int i = 0; i < 8; i++) {
      // CRC最高位
      // 后续的数据
      CRC = ((CRC >> 7) & 0x01) ? (0x07 ^ ((CRC << 1) | (cData >> 7)))
                                : ((CRC << 1) | (cData >> 7));
      cData <<= 1;

    }
  }

  return CRC;
}


// 按字节计算CRC8
unsigned char CRC_8_Byte(unsigned char* pData, int count) {
  // 生成查找表
  static unsigned char crc8Table[256] = {0};
  unsigned char crcB = 0;
  for (int i = 0; i < 0x100; ++i) {
    crcB = i;
    crc8Table[i] = CRC_8_bit(&crcB, 1);
    if ((i + 1) % 8 == 0) {
      printf(" 0x%02x\n", crc8Table[i]);
    } else {
      printf(" 0x%02x", crc8Table[i]);
    }
  }

  // 查表计算
  unsigned char CRC = 0x00;
  for (int n = 0; n < count; ++n) {
    CRC = crc8Table[CRC] ^ crc8Table[pData[n]];
  }

  return CRC;
}

unsigned char CRC_8_M(unsigned char* pData, int count) {
  return 0xFF ^ CRC_8_Byte(pData, count);  // 陪集码为0xff
                                           // 也可用
  // return 0xFF ^ CRC_8_bit(pData, count);
}

调用方法:

  char hexD[5] = {0xF1, 0x0, 0x0, 0x0, 0x00};
  crc8_CDT_init(0x07); /* 0x5E 生成表 */
  crc = crc8_CDT(0x00, hexD, 5);
  printf("CRC8_CDT_5e = 0x%02x\n", (uint8_t)crc);
  
  
  crc = CRC_8_M(hexD, 5);
  printf("CRC8_M_5e = 0x%02x\n", (uint8_t)crc);

运行结果如下:

运行结果一致:

 /* 生成crc表如下,使用crc表时,直接调用查找函数即可 */
 0x00 0x07 0x0e 0x09 0x1c 0x1b 0x12 0x15
 0x38 0x3f 0x36 0x31 0x24 0x23 0x2a 0x2d
 0x70 0x77 0x7e 0x79 0x6c 0x6b 0x62 0x65
 0x48 0x4f 0x46 0x41 0x54 0x53 0x5a 0x5d
 0xe0 0xe7 0xee 0xe9 0xfc 0xfb 0xf2 0xf5
 0xd8 0xdf 0xd6 0xd1 0xc4 0xc3 0xca 0xcd
 0x90 0x97 0x9e 0x99 0x8c 0x8b 0x82 0x85
 0xa8 0xaf 0xa6 0xa1 0xb4 0xb3 0xba 0xbd
 0xc7 0xc0 0xc9 0xce 0xdb 0xdc 0xd5 0xd2
 0xff 0xf8 0xf1 0xf6 0xe3 0xe4 0xed 0xea
 0xb7 0xb0 0xb9 0xbe 0xab 0xac 0xa5 0xa2
 0x8f 0x88 0x81 0x86 0x93 0x94 0x9d 0x9a
 0x27 0x20 0x29 0x2e 0x3b 0x3c 0x35 0x32
 0x1f 0x18 0x11 0x16 0x03 0x04 0x0d 0x0a
 0x57 0x50 0x59 0x5e 0x4b 0x4c 0x45 0x42
 0x6f 0x68 0x61 0x66 0x73 0x74 0x7d 0x7a
 0x89 0x8e 0x87 0x80 0x95 0x92 0x9b 0x9c
 0xb1 0xb6 0xbf 0xb8 0xad 0xaa 0xa3 0xa4
 0xf9 0xfe 0xf7 0xf0 0xe5 0xe2 0xeb 0xec
 0xc1 0xc6 0xcf 0xc8 0xdd 0xda 0xd3 0xd4
 0x69 0x6e 0x67 0x60 0x75 0x72 0x7b 0x7c
 0x51 0x56 0x5f 0x58 0x4d 0x4a 0x43 0x44
 0x19 0x1e 0x17 0x10 0x05 0x02 0x0b 0x0c
 0x21 0x26 0x2f 0x28 0x3d 0x3a 0x33 0x34
 0x4e 0x49 0x40 0x47 0x52 0x55 0x5c 0x5b
 0x76 0x71 0x78 0x7f 0x6a 0x6d 0x64 0x63
 0x3e 0x39 0x30 0x37 0x22 0x25 0x2c 0x2b
 0x06 0x01 0x08 0x0f 0x1a 0x1d 0x14 0x13
 0xae 0xa9 0xa0 0xa7 0xb2 0xb5 0xbc 0xbb
 0x96 0x91 0x98 0x9f 0x8a 0x8d 0x84 0x83
 0xde 0xd9 0xd0 0xd7 0xc2 0xc5 0xcc 0xcb
 0xe6 0xe1 0xe8 0xef 0xfa 0xfd 0xf4 0xf3

CDT协议中crc8校验算法

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