103 lines
2.6 KiB
C++
103 lines
2.6 KiB
C++
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// This CRC function is based on Intel Slicing-by-8 algorithm.
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//
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// Original Intel Slicing-by-8 code is available here:
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//
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// http://sourceforge.net/projects/slicing-by-8/
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//
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// Original Intel Slicing-by-8 code is licensed as:
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//
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// Copyright (c) 2004-2006 Intel Corporation - All Rights Reserved
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//
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// This software program is licensed subject to the BSD License,
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// available at http://www.opensource.org/licenses/bsd-license.html
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#include "rar.hpp"
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static uint crc_tables[8][256]; // Tables for Slicing-by-8.
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// Build the classic CRC32 lookup table.
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// We also provide this function to legacy RAR and ZIP decryption code.
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void InitCRC32(uint *CRCTab)
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{
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if (CRCTab[1]!=0)
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return;
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for (uint I=0;I<256;I++)
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{
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uint C=I;
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for (uint J=0;J<8;J++)
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C=(C & 1) ? (C>>1)^0xEDB88320 : (C>>1);
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CRCTab[I]=C;
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}
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}
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static void InitTables()
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{
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InitCRC32(crc_tables[0]);
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for (uint I=0;I<256;I++) // Build additional lookup tables.
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{
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uint C=crc_tables[0][I];
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for (uint J=1;J<8;J++)
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{
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C=crc_tables[0][(byte)C]^(C>>8);
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crc_tables[J][I]=C;
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}
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}
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}
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struct CallInitCRC {CallInitCRC() {InitTables();}} static CallInit32;
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uint CRC32(uint StartCRC,const void *Addr,size_t Size)
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{
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byte *Data=(byte *)Addr;
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// Align Data to 8 for better performance.
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for (;Size>0 && ((size_t)Data & 7);Size--,Data++)
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StartCRC=crc_tables[0][(byte)(StartCRC^Data[0])]^(StartCRC>>8);
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for (;Size>=8;Size-=8,Data+=8)
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{
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#ifdef BIG_ENDIAN
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StartCRC ^= Data[0]|(Data[1] << 8)|(Data[2] << 16)|(Data[3] << 24);
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uint NextData = Data[4]|(Data[5] << 8)|(Data[6] << 16)|(Data[7] << 24);
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#else
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StartCRC ^= *(uint32 *) Data;
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uint NextData = *(uint32 *) (Data+4);
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#endif
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StartCRC = crc_tables[7][(byte) StartCRC ] ^
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crc_tables[6][(byte)(StartCRC >> 8) ] ^
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crc_tables[5][(byte)(StartCRC >> 16)] ^
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crc_tables[4][(byte)(StartCRC >> 24)] ^
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crc_tables[3][(byte) NextData ] ^
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crc_tables[2][(byte)(NextData >>8 ) ] ^
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crc_tables[1][(byte)(NextData >> 16)] ^
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crc_tables[0][(byte)(NextData >> 24)];
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}
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for (;Size>0;Size--,Data++) // Process left data.
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StartCRC=crc_tables[0][(byte)(StartCRC^Data[0])]^(StartCRC>>8);
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return StartCRC;
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}
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#ifndef SFX_MODULE
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// For RAR 1.4 archives in case somebody still has them.
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ushort Checksum14(ushort StartCRC,const void *Addr,size_t Size)
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{
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byte *Data=(byte *)Addr;
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for (size_t I=0;I<Size;I++)
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{
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StartCRC=(StartCRC+Data[I])&0xffff;
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StartCRC=((StartCRC<<1)|(StartCRC>>15))&0xffff;
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}
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return StartCRC;
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}
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#endif
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