1 /* 7zCrcOpt.c -- CRC32 calculation : optimized version
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2 2009-11-23 : Igor Pavlov : Public domain */
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8 #define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
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10 UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table)
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12 const Byte *p = (const Byte *)data;
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13 for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
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14 v = CRC_UPDATE_BYTE_2(v, *p);
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15 for (; size >= 4; size -= 4, p += 4)
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17 v ^= *(const UInt32 *)p;
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19 table[0x300 + (v & 0xFF)] ^
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20 table[0x200 + ((v >> 8) & 0xFF)] ^
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21 table[0x100 + ((v >> 16) & 0xFF)] ^
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22 table[0x000 + ((v >> 24))];
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24 for (; size > 0; size--, p++)
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25 v = CRC_UPDATE_BYTE_2(v, *p);
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29 UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table)
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31 return CrcUpdateT4(v, data, size, table);
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