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/*
** Command & Conquer Generals Zero Hour(tm)
** Copyright 2025 Electronic Arts Inc.
**
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation, either version 3 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
////////////////////////////////////////////////////////////////////////////////
// //
// (c) 2001-2003 Electronic Arts Inc. //
// //
////////////////////////////////////////////////////////////////////////////////
// CRC.h ///////////////////////////////////////////////////////////////
// A class encapsulating CRC calculation
// Author: Matthew D. Campbell, October 2001
#pragma once
#ifndef _CRC_H_
#define _CRC_H_
#include "Lib/BaseType.h"
#include "winsock2.h" // for htonl
#ifdef _DEBUG
class CRC
{
public:
CRC() { crc = 0; }
void computeCRC( const void *buf, Int len ); ///< Compute the CRC for a buffer, added into current CRC
void clear( void ) { crc = 0; } ///< Clears the CRC to 0
// UnsignedInt get( void ) { return htonl(crc); } ///< Get the combined CRC
UnsignedInt get( void );
private:
void addCRC( UnsignedByte val ); ///< CRC a 4-byte block
UnsignedInt crc;
};
#else
// optimized inline only version
class CRC
{
public:
CRC(void) { crc=0; }
/// Compute the CRC for a buffer, added into current CRC
__forceinline void computeCRC( const void *buf, Int len )
{
if (!buf||len<1)
return;
/* C++ version left in for reference purposes
for (UnsignedByte *uintPtr=(UnsignedByte *)buf;len>0;len--,uintPtr++)
{
int hibit;
if (crc & 0x80000000)
{
hibit = 1;
}
else
{
hibit = 0;
}
crc <<= 1;
crc += *uintPtr;
crc += hibit;
}
*/
// ASM version, verified by comparing resulting data with C++ version data
unsigned *crcPtr=&crc;
_asm
{
mov esi,[buf]
mov ecx,[len]
dec ecx
mov edi,[crcPtr]
mov ebx,dword ptr [edi]
xor eax,eax
lp:
mov al,byte ptr [esi]
shl ebx,1
inc esi
adc ebx,eax
dec ecx
jns lp
mov dword ptr [edi],ebx
};
}
/// Clears the CRC to 0
void clear( void )
{
crc = 0;
}
///< Get the combined CRC
UnsignedInt get( void ) const
{
return crc;
}
private:
UnsignedInt crc;
};
#endif
#endif // _CRC_H_