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#include <iostream>
#include <cstdlib>
#include <cstring>
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 <string>\n";
return 0;
} else {
name = argv[1];
}
std::cout << crc.FullCRC((unsigned char *)name, strlen(name)) << std::endl;
}
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