1 | #include <iostream>
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2 | #include <cstdlib>
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3 | #include <cstring>
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4 |
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5 |
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6 | class CCRC32
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7 | {
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8 | public:
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9 | CCRC32() { initialize(); }
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10 |
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11 | unsigned long FullCRC(const unsigned char *sData, unsigned long ulDataLength)
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12 | {
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13 | unsigned long ulCRC = 0xffffffff;
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14 | PartialCRC(&ulCRC, sData, ulDataLength);
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15 | return(ulCRC ^ 0xffffffff);
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16 | }
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17 |
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18 | void PartialCRC(unsigned long *ulCRC, const unsigned char *sData, unsigned long ulDataLength)
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19 | {
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20 | while(ulDataLength--) {
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21 | *ulCRC = (*ulCRC >> 8) ^ ulTable[(*ulCRC & 0xFF) ^ *sData++];
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22 | }
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23 | }
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24 |
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25 | private:
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26 | void initialize(void)
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27 | {
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28 | unsigned long ulPolynomial = 0x04C11DB7;
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29 | memset(&ulTable, 0, sizeof(ulTable));
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30 | for(int iCodes = 0; iCodes <= 0xFF; iCodes++) {
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31 | ulTable[iCodes] = Reflect(iCodes, 8) << 24;
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32 | for(int iPos = 0; iPos < 8; iPos++) {
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33 | ulTable[iCodes] = (ulTable[iCodes] << 1)
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34 | ^ ((ulTable[iCodes] & (1 << 31)) ? ulPolynomial : 0);
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35 | }
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36 |
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37 | ulTable[iCodes] = Reflect(ulTable[iCodes], 32);
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38 | }
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39 | }
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40 | unsigned long Reflect(unsigned long ulReflect, const char cChar)
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41 | {
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42 | unsigned long ulValue = 0;
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43 | // Swap bit 0 for bit 7, bit 1 For bit 6, etc....
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44 | for(int iPos = 1; iPos < (cChar + 1); iPos++) {
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45 | if(ulReflect & 1) {
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46 | ulValue |= (1 << (cChar - iPos));
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47 | }
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48 | ulReflect >>= 1;
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49 | }
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50 | return ulValue;
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51 | }
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52 | unsigned long ulTable[256]; // CRC lookup table array.
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53 | };
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54 |
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55 |
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56 | int main(int argc, char **argv)
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57 | {
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58 | CCRC32 crc;
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59 | char *name;
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60 | if (argc < 2) {
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61 | std::cerr << "usage: crc <string>\n";
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62 | return 0;
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63 | } else {
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64 | name = argv[1];
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65 | }
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66 | std::cout << crc.FullCRC((unsigned char *)name, strlen(name)) << std::endl;
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67 | }
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