#include #include #include class CCRC32 { public: CCRC32() { initialize(); } unsigned long FullCRC(const unsigned char *sData, unsigned long ulDataLength) { unsigned long ulCRC = 0xffffffff; PartialCRC(&ulCRC, sData, ulDataLength); return(ulCRC ^ 0xffffffff); } void PartialCRC(unsigned long *ulCRC, const unsigned char *sData, unsigned long ulDataLength) { while(ulDataLength--) { *ulCRC = (*ulCRC >> 8) ^ ulTable[(*ulCRC & 0xFF) ^ *sData++]; } } private: void initialize(void) { unsigned long ulPolynomial = 0x04C11DB7; memset(&ulTable, 0, sizeof(ulTable)); for(int iCodes = 0; iCodes <= 0xFF; iCodes++) { ulTable[iCodes] = Reflect(iCodes, 8) << 24; for(int iPos = 0; iPos < 8; iPos++) { ulTable[iCodes] = (ulTable[iCodes] << 1) ^ ((ulTable[iCodes] & (1 << 31)) ? ulPolynomial : 0); } ulTable[iCodes] = Reflect(ulTable[iCodes], 32); } } unsigned long Reflect(unsigned long ulReflect, const char cChar) { unsigned long ulValue = 0; // Swap bit 0 for bit 7, bit 1 For bit 6, etc.... for(int iPos = 1; iPos < (cChar + 1); iPos++) { if(ulReflect & 1) { ulValue |= (1 << (cChar - iPos)); } ulReflect >>= 1; } return ulValue; } unsigned long ulTable[256]; // CRC lookup table array. }; int main(int argc, char **argv) { CCRC32 crc; char *name; if (argc < 2) { std::cerr << "usage: crc \n"; return 0; } else { name = argv[1]; } std::cout << crc.FullCRC((unsigned char *)name, strlen(name)) << std::endl; }