关于crc8,那位兄弟讲解一下，网上资料不太懂

只看该作者 · 2007-6-15 09:13

C的CRC8校验的源代码：
  //   CRC8校验
  //   X^8   +   X^2   +   X^1   +   1

  unsigned   int   code   CRC8_TAB[256]   =   {
          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
  };

  unsigned   int   CRC8_Tab(unsigned   char   xdata   *   ucPtr,   unsigned   char   ucLen)
  {
          unsigned   char   ucIndex;                 //   CRC8校验表格索引
          unsigned   char   ucCRC8   =   0;                 //   CRC8字节初始化

          //   进行CRC8位校验
          while   (ucLen   --){
                  ucIndex   =   ucCRC8   ^   (*   ucPtr   ++);
                  ucCRC8   =   CRC8_TAB[ucIndex];
          }

          //   返回CRC8校验数据
          return   (~ucCRC8);
  }

我要在我的系统里使用，那位能解释一下上面的程序

谢谢

2万 · 2007-6-15 11:01

　　也可看DS18B20的PDF文档，这个函数就是为了实现CRC的硬件计算CRC的功能，PDF中有个图，做硬件的一看就明白，单片机系统，软硬件不分家。

只看该作者 · 2007-6-15 11:30

还有一种为X^8+X^5+X^4+1
unsigned char crc8(unsigned char *ptr, unsigned char len)
{
    unsigned char i;
    unsigned char crc=0;
    while(len--)
    {
        for(i=0x80; i; i>>=1)
        {
            if(crc&0x80)
            {
                crc <<= 1;
                crc^=0x07;
            }
            else
                crc <<= 1;
            if(*ptr ++ & i )
                crc^=0x07;
        }
    }
    return(crc);
}

只看该作者 · 2012-10-29 15:43

* ucPtr 它是你要校验的数据常用数组，ucLen是你要校验的数组长度

2万 · 2012-10-29 21:16

这个支持它，算法可以自动生成。
http://www.hotpage.net.cn/HotPower_HotAjax.html

2万 · 2012-10-29 21:20

大表：
//CRC位域8表(小端):
const unsigned char CRCR8_8C_Table[256] = {
  0x00,0x5E,0xBC,0xE2,0x61,0x3F,0xDD,0x83,0xC2,0x9C,0x7E,0x20,0xA3,0xFD,0x1F,0x41,
  0x9D,0xC3,0x21,0x7F,0xFC,0xA2,0x40,0x1E,0x5F,0x01,0xE3,0xBD,0x3E,0x60,0x82,0xDC,
  0x23,0x7D,0x9F,0xC1,0x42,0x1C,0xFE,0xA0,0xE1,0xBF,0x5D,0x03,0x80,0xDE,0x3C,0x62,
  0xBE,0xE0,0x02,0x5C,0xDF,0x81,0x63,0x3D,0x7C,0x22,0xC0,0x9E,0x1D,0x43,0xA1,0xFF,
  0x46,0x18,0xFA,0xA4,0x27,0x79,0x9B,0xC5,0x84,0xDA,0x38,0x66,0xE5,0xBB,0x59,0x07,
  0xDB,0x85,0x67,0x39,0xBA,0xE4,0x06,0x58,0x19,0x47,0xA5,0xFB,0x78,0x26,0xC4,0x9A,
  0x65,0x3B,0xD9,0x87,0x04,0x5A,0xB8,0xE6,0xA7,0xF9,0x1B,0x45,0xC6,0x98,0x7A,0x24,
  0xF8,0xA6,0x44,0x1A,0x99,0xC7,0x25,0x7B,0x3A,0x64,0x86,0xD8,0x5B,0x05,0xE7,0xB9,
  0x8C,0xD2,0x30,0x6E,0xED,0xB3,0x51,0x0F,0x4E,0x10,0xF2,0xAC,0x2F,0x71,0x93,0xCD,
  0x11,0x4F,0xAD,0xF3,0x70,0x2E,0xCC,0x92,0xD3,0x8D,0x6F,0x31,0xB2,0xEC,0x0E,0x50,
  0xAF,0xF1,0x13,0x4D,0xCE,0x90,0x72,0x2C,0x6D,0x33,0xD1,0x8F,0x0C,0x52,0xB0,0xEE,
  0x32,0x6C,0x8E,0xD0,0x53,0x0D,0xEF,0xB1,0xF0,0xAE,0x4C,0x12,0x91,0xCF,0x2D,0x73,
  0xCA,0x94,0x76,0x28,0xAB,0xF5,0x17,0x49,0x08,0x56,0xB4,0xEA,0x69,0x37,0xD5,0x8B,
  0x57,0x09,0xEB,0xB5,0x36,0x68,0x8A,0xD4,0x95,0xCB,0x29,0x77,0xF4,0xAA,0x48,0x16,
  0xE9,0xB7,0x55,0x0B,0x88,0xD6,0x34,0x6A,0x2B,0x75,0x97,0xC9,0x4A,0x14,0xF6,0xA8,
  0x74,0x2A,0xC8,0x96,0x15,0x4B,0xA9,0xF7,0xB6,0xE8,0x0A,0x54,0xD7,0x89,0x6B,0x35
};
//CRC位域8查表算法(小端):
unsigned char GetCRCR8_8C_00_00_Table(unsigned char *crcBuff, unsigned char crcLen) {
unsigned char i;
unsigned char crc = 0x00;
  for(i = 0; i < crcLen; i ++) {
crc = CRCR8_8C_Table[crc ^ crcBuff[i]];
  }
  return crc;
}
void main() {
const unsigned char dataTable[] = "\x01\x23\x45\x67\x89\xAB\xCD\xEF";
unsigned char crc;
  crc = GetCRCR8_8C_00_00_Table((unsigned char *)dataTable, sizeof(dataTable) - 1);
  while(1);
}

2万 · 2012-10-29 21:20

小表：
//CRC位域4表(小端):
const unsigned char CRCR8_8C_Table[16] = {
  0x00,0x9D,0x23,0xBE,0x46,0xDB,0x65,0xF8,0x8C,0x11,0xAF,0x32,0xCA,0x57,0xE9,0x74
};
//CRC位域4查表算法(小端):
unsigned char GetCRCR8_8C_00_00_Table(unsigned char *crcBuff, unsigned char crcLen) {
unsigned char i;
unsigned char crc = 0x00;
unsigned char crcTemp;
  for(i = 0; i < (crcLen * 2); i ++) {
if (i & 1) crcTemp = crcBuff[i >> 1] >> 4;
else crcTemp = crcBuff[i >> 1] & 0x0F;
crc = (crc >> 4) ^ CRCR8_8C_Table[(crc & 0x0F) ^ crcTemp];
  }
  return crc;
}
void main() {
const unsigned char dataTable[] = "\x01\x23\x45\x67\x89\xAB\xCD\xEF";
unsigned char crc;
  crc = GetCRCR8_8C_00_00_Table((unsigned char *)dataTable, sizeof(dataTable) - 1);
  while(1);
}

关于crc8,那位兄弟讲解一下，网上资料不太懂

相关下载

相关帖子

看DS18B20的应用笔记

这个生成多项式为x^8+X^2+X^1+1,不用查表法如下：

突出贡献奖章

技术导师奖章

技术奇才奖章

精华达人奖章

湍急之河流

以坛为家

技术新星奖章