BizHawk/libmupen64plus/mupen64plus-video-glide64/src/CRC.h

92 lines
2.8 KiB
C

/*
* Glide64 - Glide video plugin for Nintendo 64 emulators.
* Copyright (c) 2002 Dave2001
* Copyright (c) 2008 Günther <guenther.emu@freenet.de>
*
* 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
* Licence along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA
*/
//****************************************************************
//
// Glide64 - Glide Plugin for Nintendo 64 emulators (tested mostly with Project64)
// Project started on December 29th, 2001
//
// 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.
//
// Official Glide64 development channel: #Glide64 on EFnet
//
// Original author: Dave2001 (Dave2999@hotmail.com)
// Other authors: Gonetz, Gugaman
//
//****************************************************************
//
// CRC32 calculation functions
//
// Created by Gonetz, 2004
//
//****************************************************************
#if !defined(WIN32) && defined(GCC)
#define Crc32 _Crc32
#define CRCTable _CRCTable
#endif
extern unsigned int CRCTable[ 256 ];
void CRC_BuildTable();
inline unsigned int CRC_Calculate( unsigned int crc, const void *buffer, unsigned int count )
{
#if !defined(__GNUC__) && !defined(NO_ASM)
unsigned int Crc32=crc;
__asm {
mov esi, buffer
mov edx, count
add edx, esi
mov ecx, crc
loop1:
mov bl, byte ptr [esi]
movzx eax, cl
inc esi
xor al, bl
shr ecx, 8
mov ebx, [CRCTable+eax*4]
xor ecx, ebx
cmp edx, esi
jne loop1
xor Crc32, ecx
}
return Crc32;
#else
unsigned int result = crc;
for (const char * p = (const char*)buffer; p != (const char*)buffer + count; ++p)
{
unsigned char al = result;
al ^= *p;
result >>= 8;
result ^= CRCTable[al];
}
result ^= crc;
return result;
#endif
}