--- /dev/null
+/******************************************************************************
+ * Arachnoid Graphics Plugin for Mupen64Plus
+ * http://bitbucket.org/wahrhaft/mupen64plus-video-arachnoid/
+ *
+ * Copyright (C) 2007 Kristofer Karlsson, Rickard Niklasson
+ *
+ * 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 (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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *****************************************************************************/
+
+#include "CRCCalculator.h"
+
+#define CRC32_POLYNOMIAL 0xedb88320L //0x04C11DB7
+typedef unsigned char byte;
+
+//-----------------------------------------------------------------------------
+// Static Variabels
+//-----------------------------------------------------------------------------
+unsigned int CRCCalculator::m_crcTable[256] = {0};
+
+static unsigned int crc_table[256];
+
+//-----------------------------------------------------------------------------
+//! Constructor
+//-----------------------------------------------------------------------------
+CRCCalculator::CRCCalculator()
+{
+ static bool hashTableInitialized = false;
+
+ //Build hash table
+ //http://www.gamedev.net/reference/articles/article1941.asp
+ if ( !hashTableInitialized )
+ {
+ // unsigned int crc;
+
+ // //For each value
+ // for (int i=0; i<256; i++)
+ //{
+ // crc = _reflect( i, 8 ) << 24;
+
+ // for (int j = 0; j < 8; j++)
+ // {
+ // crc = (crc << 1) ^ (crc & (1 << 31) ? CRC32_POLYNOMIAL : 0);
+ // }
+ //
+ // m_crcTable[i] = _reflect( crc, 32 );
+ // }
+
+ unsigned int crc;
+ unsigned int poly; // polynomial exclusive-or pattern
+ // terms of polynomial defining this crc (except x^32):
+ static const unsigned char p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
+
+ /* make exclusive-or pattern from polynomial (0xedb88320L) */
+ poly = 0L;
+ for (unsigned int n = 0; n < sizeof(p)/sizeof(unsigned char); n++)
+ {
+ poly |= 1L << (31 - p[n]);
+ }
+
+ for (int n=0; n<256; ++n)
+ {
+ crc = (unsigned int)n;
+
+ for (int k = 0; k < 8; k++)
+ {
+ crc = (crc & 1) ? (poly ^ (crc >> 1)) : crc >> 1;
+ }
+ crc_table[n] = crc;
+ }
+
+ hashTableInitialized = true;
+ }
+}
+
+//-----------------------------------------------------------------------------
+// CalculateCRC
+//-----------------------------------------------------------------------------
+#define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
+#define DO1b(buf) crc = (crc >> 8) ^ crc_table[(crc & 0xFF) ^ *buf++]
+unsigned int CRCCalculator::calcCRC(unsigned int crc, void *buffer, unsigned int count)
+{
+ byte* p = (byte*) buffer;
+ //unsigned int orig = crc;
+
+ // p = (byte*) buffer;
+ // while (count--)
+ // {
+ // crc = (crc >> 8) ^ m_crcTable[(crc & 0xFF) ^ *p++];
+ // }
+
+ // return crc ^ orig;
+
+ if (buffer == 0) return 0L;
+
+ crc = crc ^ 0xffffffffL;
+ while (count--)
+ {
+ crc = crc_table[((int)crc ^ (*p++)) & 0xff] ^ (crc >> 8);
+ }
+ // if (len) do {
+ // DO1(buf);
+ // } while (--len);
+ return crc ^ 0xffffffffL;
+}
+
+//-----------------------------------------------------------------------------
+// CalculatePaletteCRC
+//-----------------------------------------------------------------------------
+unsigned int CRCCalculator::calcPaletteCRC(unsigned int crc, void *buffer, unsigned int count)
+{
+ byte *p;
+ unsigned int orig = crc;
+
+ p = (byte*) buffer;
+ while (count--)
+ {
+ crc = (crc >> 8) ^ m_crcTable[(crc & 0xFF) ^ *p++];
+ crc = (crc >> 8) ^ m_crcTable[(crc & 0xFF) ^ *p++];
+
+ p += 6;
+ }
+
+ return crc ^ orig;
+}
+
+//*****************************************************************************
+// Private Functions
+//*****************************************************************************
+
+//-----------------------------------------------------------------------------
+//* Reflect
+//! Help function when creating the CRC Table
+//! Swaps bit 0 for bit 7
+//! bit 1 for bit 6
+//! bit 2 for bit 5 ...
+//-----------------------------------------------------------------------------
+unsigned int CRCCalculator::_reflect(unsigned int ref, char ch)
+{
+ unsigned int value = 0;
+ for (int i=1; i<(ch + 1); ++i)
+ {
+ if(ref & 1)
+ {
+ value |= 1 << (ch - i);
+ }
+ ref >>= 1;
+ }
+ return value;
+}