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1、1 CRC 16 计算算法OxFFFF CRC16 CRC16 XOR 字节 CRC16 N=0 CRC16 右移 1 位进位CRC16 XOR POLY CRC 16 N=N+1 N 7 Yes No No Yes 报文结束？Yes No 结束后续子节XOR=异或N=字节的信息位POLY=CRC 16 多项式计算 =1010 0000 0000 0001(生成多项式 =1+x+x +x)在 CRC 16 中，发送的第一个字节为低字节.2 CRC 计算示例 (帧 02 07)CRC 寄存器初始化1111111111111111XOR 第一个字符0000000000000000111111111
2、1111101移位 1011111111111111011010000000000001标志 1，XOR 多项式1101111111111111移位 201101111111111111标志 1，XOR 多项式10100000000000011100111111111110移位 301100111111111100移位 40011001111111111110100000000000011001001111111110移位 501001001111111110移位 60010010011111111110100000000000011000010011111110移位 701000010011
3、111110移位 800100001001111110101000000000000110000001001111100000000000000111XOR 第二个字符1000000100111001移位 10100000010011100110100000000000011110000010011101移位 20111000001001110110100000000000011101000001001111移位 30110100000100111110100000000000013 1100100000100110移位 401100100000100110移位 500110010000010
4、01110100000000000011001001000001000移位 601001001000001000移位 700100100100000100移位 800010010010000010最高有效最低有效帧的 CRC 16 则为:4112例执行 CRC 生成的 C 语言的函数在下面示出。所有的可能的CRC 值都被预装在两个数组中，当计算报文内容时可以简单的索引即可。一个数组含有16 位 CRC 域的所有 256 个可能的高位字节，另一个数组含有地位字节的值。这种索引访问CRC 的方式提供了比对报文缓冲区的每个新字符都计算新的CRC 更快的方法。注意:此函数内部执行高/低 CRC 字节的
5、交换。此函数返回的是已经经过交换的 CRC 值。也就是说，从该函数返回的 CRC 值可以直接放置于报文用于发送。函数使用两个参数:unsigned char*puchMsg;指向含有用于生成 CRC 的二进制数据报文缓冲区的指针unsigned short usDataLen;报文缓冲区的字节数.CRC 生成函数unsigned short CRC16(puchMsg，usDataLen)/unsigned char*puchMsg;/*用于 计 算CRC 的报 文*/unsigned short usDataLen;/*报文中的字节数*/unsigned char uchCRCHi=0 xF
6、F;/*CRC 的高字节初始化*/unsigned char uchCRCLo=0 xFF;/*CRC 的低字节初始化4*/unsigned uIndex;/*CRC 查询表索引*/while(usDataLen-)/*完成整个报文缓冲区*/uIndex=uchCRCLo *puchMsgg+;/*计算CRC */uchCRCLo=uchCRCHi auchCRCHiuIndex;uchCRCHi=auchCRCLouIndex;return(uchCRCHi 8|uchCRCLo);5 高字节表/*高位字节的CRC 值*/static unsigned char auchCRCHi=0 x0
7、0,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x8
8、1,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x0
9、1,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x8
10、0,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x0
11、1,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x00,0 xC1,0 x81,0 x40,0 x01,0 xC0,0 x80,0 x41,0 x01,0 xC0,0 x8
12、0,0 x41,0 x00,0 xC1,0 x81,0 x40;6 低字节表/*低位字节的CRC 值*/static char auchCRCLo=0 x00,0 xC0,0 xC1,0 x01,0 xC3,0 x03,0 x02,0 xC2,0 xC6,0 x06,0 x07,0 xC7,0 x05,0 xC5,0 xC4,0 x04,0 xCC,0 x0C,0 x0D,0 xCD,0 x0F,0 xCF,0 xCE,0 x0E,0 x0A,0 xCA,0 xCB,0 x0B,0 xC9,0 x09,0 x08,0 xC8,0 xD8,0 x18,0 x19,0 xD9,0 x1B,0 xD
13、B,0 xDA,0 x1A,0 x1E,0 xDE,0 xDF,0 x1F,0 xDD,0 x1D,0 x1C,0 xDC,0 x14,0 xD4,0 xD5,0 x15,0 xD7,0 x17,0 x16,0 xD6,0 xD2,0 x12,0 x13,0 xD3,0 x11,0 xD1,0 xD0,0 x10,0 xF0,0 x30,0 x31,0 xF1,0 x33,0 xF3,0 xF2,0 x32,0 x36,0 xF6,0 xF7,0 x37,0 xF5,0 x35,0 x34,0 xF4,0 x3C,0 xFC,0 xFD,0 x3D,0 xFF,0 x3F,0 x3E,0 xF
14、E,0 xFA,0 x3A,0 x3B,0 xFB,0 x39,0 xF9,0 xF8,0 x38,0 x28,0 xE8,0 xE9,0 x29,0 xEB,0 x2B,0 x2A,0 xEA,0 xEE,0 x2E,0 x2F,0 xEF,0 x2D,0 xED,0 xEC,0 x2C,0 xE4,0 x24,0 x25,0 xE5,0 x27,0 xE7,0 xE6,0 x26,0 x22,0 xE2,0 xE3,0 x23,0 xE1,0 x21,0 x20,0 xE0,0 xA0,0 x60,0 x61,0 xA1,0 x63,0 xA3,0 xA2,0 x62,0 x66,0 xA
15、6,0 xA7,0 x67,0 xA5,0 x65,0 x64,0 xA4,0 x6C,0 xAC,0 xAD,0 x6D,0 xAF,0 x6F,0 x6E,0 xAE,0 xAA,0 x6A,0 x6B,0 xAB,0 x69,0 xA9,0 xA8,0 x68,0 x78,0 xB8,0 xB9,0 x79,0 xBB,0 x7B,0 x7A,0 xBA,0 xBE,0 x7E,0 x7F,0 xBF,0 x7D,0 xBD,0 xBC,0 x7C,0 xB4,0 x74,0 x75,0 xB5,0 x77,0 xB7,0 xB6,0 x76,0 x72,0 xB2,0 xB3,0 x7
16、3,0 xB1,0 x71,0 x70,0 xB0,0 x50,0 x90,0 x91,0 x51,0 x93,0 x53,0 x52,0 x92,0 x96,0 x56,0 x57,0 x97,0 x55,0 x95,0 x94,0 x54,0 x9C,0 x5C,0 x5D,0 x9D,0 x5F,0 x9F,0 x9E,0 x5E,0 x5A,0 x9A,0 x9B,0 x5B,0 x99,0 x59,0 x58,0 x98,0 x88,0 x48,0 x49,0 x89,0 x4B,0 x8B,0 x8A,0 x4A,0 x4E,0 x8E,0 x8F,0 x4F,0 x8D,0 x4D,0 x4C,0 x8C,0 x44,0 x84,0 x85,0 x45,0 x87,0 x47,0 x46,0 x86,0 x82,0 x42,0 x43,0 x83,0 x41,0 x81,0 x80,0 x40;