Arachnoid GLESv1.1 plugin. Compile and run (a bit glitchy and no frameskip) on the...

[mupen64plus-pandora.git] / source / mupen64plus-video-arachnoid / src / hash / CRCCalculator2.cpp

diff --git a/source/mupen64plus-video-arachnoid/src/hash/CRCCalculator2.cpp b/source/mupen64plus-video-arachnoid/src/hash/CRCCalculator2.cpp
new file mode 100755 (executable)
index 0000000..f0950da
--- /dev/null
+++ b/source/mupen64plus-video-arachnoid/src/hash/CRCCalculator2.cpp
@@ -0,0 +1,122 @@
+/******************************************************************************
+ * 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 "CRCCalculator2.h"
+
+#define CRC32_POLYNOMIAL    0xedb88320    //0x04C11DB7
+typedef unsigned char byte;
+
+//-----------------------------------------------------------------------------
+// Static Variabels
+//-----------------------------------------------------------------------------
+unsigned int CRCCalculator2::m_crcTable[256] = {0};
+
+//-----------------------------------------------------------------------------
+//! Constructor
+//-----------------------------------------------------------------------------
+CRCCalculator2::CRCCalculator2()
+{
+    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 );
+        }
+
+        hashTableInitialized = true;
+    }
+}
+
+//-----------------------------------------------------------------------------
+// CalculateCRC
+//-----------------------------------------------------------------------------
+unsigned int CRCCalculator2::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;
+}
+
+//-----------------------------------------------------------------------------
+// CalculatePaletteCRC
+//-----------------------------------------------------------------------------
+unsigned int CRCCalculator2::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 CRCCalculator2::_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;
+}