CRC16 check的源代码

[函数说明]

WORD _get_CRC16( char *buf, WORD count )
得到count个char的buf的CRC值

void _set_CRC16( char *buf, WORD count ,WORD crcpos) //crcpos从0计
设置buf前两个元素为CRC存储位置(0,1)

bool _check_CRC16( char *buf, WORD count ,WORD crcpos) //crcpos从0计
检验buf的crcpos+2开始的CRC值是否正确

//CRC16 check


#define xcrc(crc,cp) (crctab[((crc>>8)&0xff)^(cp&0xff)]^(crc<<8))
WORD _get_CRC16( char *buf, WORD count )
{
static WORD crctab[256] =
{
0×0000, 0×1021, 0×2042, 0×3063, 0×4084, 0x50A5, 0x60C6, 0x70E7,
0×8108, 0×9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
0×1231, 0×0210, 0×3273, 0×2252, 0x52B5, 0×4294, 0x72F7, 0x62D6,
0×9339, 0×8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
0×2462, 0×3443, 0×0420, 0×1401, 0x64E6, 0x74C7, 0x44A4, 0×5485,
0xA56A, 0xB54B, 0×8528, 0×9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
0×3653, 0×2672, 0×1611, 0×0630, 0x76D7, 0x66F6, 0×5695, 0x46B4,
0xB75B, 0xA77A, 0×9719, 0×8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
0x48C4, 0x58E5, 0×6886, 0x78A7, 0×0840, 0×1861, 0×2802, 0×3823,
0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0×8948, 0×9969, 0xA90A, 0xB92B,
0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
0×9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
0×1080, 0x00A1, 0x30C2, 0x20E3, 0×5004, 0×4025, 0×7046, 0×6067,
0x83B9, 0×9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
0x02B1, 0×1290, 0x22F3, 0x32D2, 0×4235, 0×5214, 0×6277, 0×7256,
0xB5EA, 0xA5CB, 0x95A8, 0×8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
0x34E2, 0x24C3, 0x14A0, 0×0481, 0×7466, 0×6447, 0×5424, 0×4405,
0xA7DB, 0xB7FA, 0×8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
0x26D3, 0x36F2, 0×0691, 0x16B0, 0×6657, 0×7676, 0×4615, 0×5634,
0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
0×5844, 0×4865, 0×7806, 0×6827, 0x18C0, 0x08E1, 0×3882, 0x28A3,
0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};
WORD crc, i;
char *ptr = buf;

for( crc=i=0; i<count; i++,ptr++ )
crc = xcrc(crc,(char)*ptr);
return crc;
}

void _set_CRC16( char *buf, WORD count ,WORD crcpos) //crcpos从0计
{
WORD crc;
buf[crcpos] = 0;
buf[crcpos+1] = 0;
crc = _get_CRC16( buf, count );
memcpy(buf+crcpos,&crc,2);
}

bool _check_CRC16( char *buf, WORD count ,WORD crcpos) //crcpos从0计
{
WORD o_crc;
memcpy(&o_crc,buf+crcpos,2);
buf[crcpos] = 0;
buf[crcpos+1] = 0;
return (o_crc == _get_CRC16( buf, count ));
}