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1 /* 7zCrc.c -- CRC32 calculation
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2 2008-08-05
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3 Igor Pavlov
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4 Public domain */
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5
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6 #include "7zCrc.h"
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7
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8 #define kCrcPoly 0xEDB88320
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9 UInt32 g_CrcTable[256];
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10
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11 void MY_FAST_CALL CrcGenerateTable(void)
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12 {
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13 UInt32 i;
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14 for (i = 0; i < 256; i++)
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15 {
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16 UInt32 r = i;
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17 int j;
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18 for (j = 0; j < 8; j++)
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19 r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
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20 g_CrcTable[i] = r;
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21 }
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22 }
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23
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24 UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
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25 {
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26 const Byte *p = (const Byte *)data;
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27 for (; size > 0 ; size--, p++)
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28 v = CRC_UPDATE_BYTE(v, *p);
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29 return v;
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30 }
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31
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32 UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
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33 {
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34 return CrcUpdate(CRC_INIT_VAL, data, size) ^ 0xFFFFFFFF;
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35 }
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