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code@koerner-de.net
75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
/*
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This file is part of Universal Modding Engine.
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Universal Modding Engine is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Universal Modding Engine is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Universal Modding Engine. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "uMod_Main.h"
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void GetHash( unsigned char *str, unsigned int len, DWORD64 &hash) // estimate the hash
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{
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DWORD32 hash1 = hash & 0xFFFFFFFF;
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DWORD32 hash2 = hash>>32 & 0xFFFFFFFF;
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for (int i=0; i<len; i++)
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{
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hash1 = ((hash1 << 5) + hash1) + *str; // D.J. Bernsteins algorithm (djb2)
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hash2 = *str + (hash2<< 6) + (hash2 << 16) - hash2; // SDBM algorithm
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str++;
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}
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hash = hash2;
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hash<<=32;
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hash |= hash1;
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}
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/*
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*
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* BIG THANKS TO RS !!
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*
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* who gave me his hashing algorithm (well or crc32 algorithm^^)
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*
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The hash function is CRC32 using polynomial 0xEDB88320.
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However, the hashed data is calculated incorrectly in TexMod: it's simply BytesPerPixel * Width * Height, from the beginning of the data (that is mapped using LockRect).
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The problem is that it doesn't take the pitch into account and BytesPerPixel may be wrong for some rare formats (not sure about that).
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*/
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#define CRC32POLY 0xEDB88320u /* CRC-32 Polynom */
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#define ulCrc_in 0xffffffff
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DWORD32 GetCRC32( char *pcDatabuf, unsigned int ulDatalen)
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{
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unsigned int crc = ulCrc_in;
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for (unsigned int idx = 0u; idx<ulDatalen; idx++)
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{
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unsigned int data = *pcDatabuf++;
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for (unsigned int bit = 0u; bit<8u; bit++, data >>=1)
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{
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crc = (crc >> 1) ^ (((crc ^ data) & 1) ? CRC32POLY : 0);
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}
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}
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return (crc);
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}
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