128 lines
2.9 KiB
C
128 lines
2.9 KiB
C
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/*
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** Command & Conquer Generals Zero Hour(tm)
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** Copyright 2025 Electronic Arts Inc.
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**
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** This program 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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**
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** This program 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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**
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** You should have received a copy of the GNU General Public License
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** along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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////////////////////////////////////////////////////////////////////////////////
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// //
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// (c) 2001-2003 Electronic Arts Inc. //
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// //
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////////////////////////////////////////////////////////////////////////////////
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// CRC.h ///////////////////////////////////////////////////////////////
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// A class encapsulating CRC calculation
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// Author: Matthew D. Campbell, October 2001
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#pragma once
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#ifndef _CRC_H_
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#define _CRC_H_
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#include "Lib/BaseType.h"
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#include "winsock2.h" // for htonl
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#ifdef _DEBUG
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class CRC
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{
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public:
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CRC() { crc = 0; }
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void computeCRC( const void *buf, Int len ); ///< Compute the CRC for a buffer, added into current CRC
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void clear( void ) { crc = 0; } ///< Clears the CRC to 0
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// UnsignedInt get( void ) { return htonl(crc); } ///< Get the combined CRC
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UnsignedInt get( void );
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private:
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void addCRC( UnsignedByte val ); ///< CRC a 4-byte block
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UnsignedInt crc;
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};
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#else
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// optimized inline only version
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class CRC
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{
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public:
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CRC(void) { crc=0; }
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/// Compute the CRC for a buffer, added into current CRC
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__forceinline void computeCRC( const void *buf, Int len )
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{
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if (!buf||len<1)
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return;
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/* C++ version left in for reference purposes
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for (UnsignedByte *uintPtr=(UnsignedByte *)buf;len>0;len--,uintPtr++)
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{
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int hibit;
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if (crc & 0x80000000)
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{
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hibit = 1;
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}
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else
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{
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hibit = 0;
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}
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crc <<= 1;
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crc += *uintPtr;
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crc += hibit;
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}
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*/
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// ASM version, verified by comparing resulting data with C++ version data
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unsigned *crcPtr=&crc;
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_asm
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{
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mov esi,[buf]
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mov ecx,[len]
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dec ecx
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mov edi,[crcPtr]
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mov ebx,dword ptr [edi]
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xor eax,eax
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lp:
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mov al,byte ptr [esi]
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shl ebx,1
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inc esi
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adc ebx,eax
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dec ecx
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jns lp
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mov dword ptr [edi],ebx
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};
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}
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/// Clears the CRC to 0
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void clear( void )
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{
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crc = 0;
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}
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///< Get the combined CRC
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UnsignedInt get( void ) const
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{
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return crc;
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}
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private:
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UnsignedInt crc;
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};
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#endif
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#endif // _CRC_H_
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