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https://github.com/mupen64plus/mupen64plus-oldsvn.git
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77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
/*
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* Glide64 - Glide video plugin for Nintendo 64 emulators.
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* Copyright (c) 2002 Dave2001
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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 2 of the License, or
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* 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
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* Licence along with this program; if not, write to the Free
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* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301, USA
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*/
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//****************************************************************
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//
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// Glide64 - Glide Plugin for Nintendo 64 emulators (tested mostly with Project64)
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// Project started on December 29th, 2001
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//
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// To modify Glide64:
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// * 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.
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// * 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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//
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// Official Glide64 development channel: #Glide64 on EFnet
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//
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// Original author: Dave2001 (Dave2999@hotmail.com)
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// Other authors: Gonetz, Gugaman
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//
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//****************************************************************
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//
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// CRC32 calculation functions
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//
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// Created by Gonetz, 2004
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//
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//****************************************************************
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#include "CRC.h"
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#define CRC32_POLYNOMIAL 0x04C11DB7
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unsigned int CRCTable[ 256 ];
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unsigned int Reflect( unsigned long 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
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// bit 1 for bit 6, etc.
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for (char i = 1; i < (ch + 1); i++)
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{
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if(ref & 1)
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value |= 1 << (ch - i);
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ref >>= 1;
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}
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return value;
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}
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void CRC_BuildTable()
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{
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unsigned int crc;
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for (unsigned i = 0; i <= 255; i++)
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{
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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);
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CRCTable[i] = Reflect( crc, 32 );
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}
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}
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