DCMoHo/crc.cpp at master · stuart73/DCMoHo · GitHub

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unsigned long CRC32Table[256]=
{
       0x000000000, 0x077073096, 0x0ee0e612c, 0x0990951ba,
       0x0076dc419, 0x0706af48f, 0x0e963a535, 0x09e6495a3,
       0x00edb8832, 0x079dcb8a4, 0x0e0d5e91e, 0x097d2d988,
       0x009b64c2b, 0x07eb17cbd, 0x0e7b82d07, 0x090bf1d91,

       0x01db71064, 0x06ab020f2, 0x0f3b97148, 0x084be41de,
       0x01adad47d, 0x06ddde4eb, 0x0f4d4b551, 0x083d385c7,
       0x0136c9856, 0x0646ba8c0, 0x0fd62f97a, 0x08a65c9ec,
       0x014015c4f, 0x063066cd9, 0x0fa0f3d63, 0x08d080df5,

       0x03b6e20c8, 0x04c69105e, 0x0d56041e4, 0x0a2677172,
       0x03c03e4d1, 0x04b04d447, 0x0d20d85fd, 0x0a50ab56b,
       0x035b5a8fa, 0x042b2986c, 0x0dbbbc9d6, 0x0acbcf940,
       0x032d86ce3, 0x045df5c75, 0x0dcd60dcf, 0x0abd13d59,

       0x026d930ac, 0x051de003a, 0x0c8d75180, 0x0bfd06116,
       0x021b4f4b5, 0x056b3c423, 0x0cfba9599, 0x0b8bda50f,
       0x02802b89e, 0x05f058808, 0x0c60cd9b2, 0x0b10be924,
       0x02f6f7c87, 0x058684c11, 0x0c1611dab, 0x0b6662d3d,

       0x076dc4190, 0x001db7106, 0x098d220bc, 0x0efd5102a,
       0x071b18589, 0x006b6b51f, 0x09fbfe4a5, 0x0e8b8d433,
       0x07807c9a2, 0x00f00f934, 0x09609a88e, 0x0e10e9818,
       0x07f6a0dbb, 0x0086d3d2d, 0x091646c97, 0x0e6635c01,

       0x06b6b51f4, 0x01c6c6162, 0x0856530d8, 0x0f262004e,
       0x06c0695ed, 0x01b01a57b, 0x08208f4c1, 0x0f50fc457,
       0x065b0d9c6, 0x012b7e950, 0x08bbeb8ea, 0x0fcb9887c,
       0x062dd1ddf, 0x015da2d49, 0x08cd37cf3, 0x0fbd44c65,

       0x04db26158, 0x03ab551ce, 0x0a3bc0074, 0x0d4bb30e2,
       0x04adfa541, 0x03dd895d7, 0x0a4d1c46d, 0x0d3d6f4fb,
       0x04369e96a, 0x0346ed9fc, 0x0ad678846, 0x0da60b8d0,
       0x044042d73, 0x033031de5, 0x0aa0a4c5f, 0x0dd0d7cc9,

       0x05005713c, 0x0270241aa, 0x0be0b1010, 0x0c90c2086,
       0x05768b525, 0x0206f85b3, 0x0b966d409, 0x0ce61e49f,
       0x05edef90e, 0x029d9c998, 0x0b0d09822, 0x0c7d7a8b4,
       0x059b33d17, 0x02eb40d81, 0x0b7bd5c3b, 0x0c0ba6cad,

       0x0edb88320, 0x09abfb3b6, 0x003b6e20c, 0x074b1d29a,
       0x0ead54739, 0x09dd277af, 0x004db2615, 0x073dc1683,
       0x0e3630b12, 0x094643b84, 0x00d6d6a3e, 0x07a6a5aa8,
       0x0e40ecf0b, 0x09309ff9d, 0x00a00ae27, 0x07d079eb1,

       0x0f00f9344, 0x08708a3d2, 0x01e01f268, 0x06906c2fe,
       0x0f762575d, 0x0806567cb, 0x0196c3671, 0x06e6b06e7,
       0x0fed41b76, 0x089d32be0, 0x010da7a5a, 0x067dd4acc,
       0x0f9b9df6f, 0x08ebeeff9, 0x017b7be43, 0x060b08ed5,

       0x0d6d6a3e8, 0x0a1d1937e, 0x038d8c2c4, 0x04fdff252,
       0x0d1bb67f1, 0x0a6bc5767, 0x03fb506dd, 0x048b2364b,
       0x0d80d2bda, 0x0af0a1b4c, 0x036034af6, 0x041047a60,
       0x0df60efc3, 0x0a867df55, 0x0316e8eef, 0x04669be79,

       0x0cb61b38c, 0x0bc66831a, 0x0256fd2a0, 0x05268e236,
       0x0cc0c7795, 0x0bb0b4703, 0x0220216b9, 0x05505262f,
       0x0c5ba3bbe, 0x0b2bd0b28, 0x02bb45a92, 0x05cb36a04,
       0x0c2d7ffa7, 0x0b5d0cf31, 0x02cd99e8b, 0x05bdeae1d,

       0x09b64c2b0, 0x0ec63f226, 0x0756aa39c, 0x0026d930a,
       0x09c0906a9, 0x0eb0e363f, 0x072076785, 0x005005713,
       0x095bf4a82, 0x0e2b87a14, 0x07bb12bae, 0x00cb61b38,
       0x092d28e9b, 0x0e5d5be0d, 0x07cdcefb7, 0x00bdbdf21,

       0x086d3d2d4, 0x0f1d4e242, 0x068ddb3f8, 0x01fda836e,
       0x081be16cd, 0x0f6b9265b, 0x06fb077e1, 0x018b74777,
       0x088085ae6, 0x0ff0f6a70, 0x066063bca, 0x011010b5c,
       0x08f659eff, 0x0f862ae69, 0x0616bffd3, 0x0166ccf45,

       0x0a00ae278, 0x0d70dd2ee, 0x04e048354, 0x03903b3c2,
       0x0a7672661, 0x0d06016f7, 0x04969474d, 0x03e6e77db,
       0x0aed16a4a, 0x0d9d65adc, 0x040df0b66, 0x037d83bf0,
       0x0a9bcae53, 0x0debb9ec5, 0x047b2cf7f, 0x030b5ffe9,

       0x0bdbdf21c, 0x0cabac28a, 0x053b39330, 0x024b4a3a6,
       0x0bad03605, 0x0cdd70693, 0x054de5729, 0x023d967bf,
       0x0b3667a2e, 0x0c4614ab8, 0x05d681b02, 0x02a6f2b94,
       0x0b40bbe37, 0x0c30c8ea1, 0x05a05df1b, 0x02d02ef8d
};

unsigned long ComputeCRC32Part(unsigned char *buf,int len,unsigned long  crc)
{
   for(int i=0;i<len;i++)
   {
		int index=(crc^(*buf++))&0xff;
		crc=((crc>>8)^CRC32Table[index]);
   }
	return crc;
}

unsigned long ComputeCRC32(unsigned char *buf,int len)
{
	return ~ComputeCRC32Part(buf,len,0xffffffff);
}