project64/Source/Glide64/CRC.cpp

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/*
* Glide64 - Glide video plugin for Nintendo 64 emulators.
* Copyright (c) 2002 Dave2001
* Copyright (c) 2003-2009 Sergey 'Gonetz' Lipski
*
* 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 2 of the License, or
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
//****************************************************************
//
// Glide64 - Glide Plugin for Nintendo 64 emulators
// Project started on December 29th, 2001
//
// Authors:
// Dave2001, original author, founded the project in 2001, left it in 2002
// Gugaman, joined the project in 2002, left it in 2002
// Sergey 'Gonetz' Lipski, joined the project in 2002, main author since fall of 2002
// Hiroshi 'KoolSmoky' Morii, joined the project in 2007
//
//****************************************************************
//
// To modify Glide64:
// * Write your name and (optional)email, commented by your work, so I know who did it, and so that you can find which parts you modified when it comes time to send it to me.
// * Do NOT send me the whole project or file that you modified. Take out your modified code sections, and tell me where to put them. If people sent the whole thing, I would have many different versions, but no idea how to combine them all.
//
//****************************************************************
//
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// CRC32 calculation functions
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//
// Created by Gonetz, 2004
//
//****************************************************************
//*
#define CRC32_POLYNOMIAL 0x04C11DB7
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unsigned int CRCTable[256];
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unsigned int Reflect(unsigned int ref, char ch)
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{
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unsigned int value = 0;
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// Swap bit 0 for bit 7
// bit 1 for bit 6, etc.
for (char i = 1; i < (ch + 1); i++)
{
if (ref & 1)
value |= 1 << (ch - i);
ref >>= 1;
}
return value;
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}
void CRC_BuildTable()
{
unsigned int crc;
for (unsigned i = 0; i <= 255; i++)
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{
crc = Reflect(i, 8) << 24;
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for (unsigned j = 0; j < 8; j++)
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crc = (crc << 1) ^ (crc & (1 << 31) ? CRC32_POLYNOMIAL : 0);
CRCTable[i] = Reflect(crc, 32);
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}
}
//*/
//*
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unsigned int CRC32(unsigned int crc, void *buffer, unsigned int count)
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{
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unsigned int orig = crc;
unsigned char * p = reinterpret_cast<unsigned char*>(buffer);
while (count--)
crc = (crc >> 8) ^ CRCTable[(crc & 0xFF) ^ *p++];
return crc ^ orig;
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}
//*/
/*
uint32_t CRC_Calculate( uint32_t crc, void *buffer, uint32_t count )
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{
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uint32_t Crc32=crc;
__asm {
mov esi, buffer
mov ecx, count
mov edx, crc
xor eax, eax
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loop1:
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inc esi
mov al, dl
xor al, byte ptr [esi]
shr edx, 8
mov ebx, [CRCTable+eax*4]
xor edx, ebx
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loop loop1
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xor Crc32, edx
}
return Crc32;
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}
*/
/*
unsigned int CRC_Calculate( unsigned int crc, void *buffer, unsigned int count )
{
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unsigned int Crc32=crc;
__asm {
mov esi, buffer
mov edx, count
add edx, esi
mov ecx, crc
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loop1:
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mov bl, byte ptr [esi]
movzx eax, cl
inc esi
xor al, bl
shr ecx, 8
mov ebx, [CRCTable+eax*4]
xor ecx, ebx
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cmp edx, esi
jne loop1
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xor Crc32, ecx
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}
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return Crc32;
}
//*/