JMA Support.

zsnes/src/jma/lencoder.h

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+/*
+Copyright (C) 2002 Andrea Mazzoleni ( http://advancemame.sf.net )
+Copyright (C) 2001-4 Igor Pavlov ( http://www.7-zip.org )
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public
+License as published by the Free Software Foundation; either
+version 2.1 of the License, or (at your option) any later version.
+
+This library 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
+Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with this library; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*/
+
+#ifndef __LENCODER_H
+#define __LENCODER_H
+
+#include "btreecd.h"
+
+namespace NLength {
+
+const int kNumPosStatesBitsMax = 4;
+const int kNumPosStatesMax = (1 << kNumPosStatesBitsMax);
+
+
+const int kNumPosStatesBitsEncodingMax = 4;
+const int kNumPosStatesEncodingMax = (1 << kNumPosStatesBitsEncodingMax);
+
+
+const int kNumMoveBits = 5;
+
+const int kNumLenBits = 3;
+const int kNumLowSymbols = 1 << kNumLenBits;
+const int kNumMidBits = 3;
+const int kNumMidSymbols = 1 << kNumMidBits;
+
+const int kNumHighBits = 8;
+
+const int kNumSymbolsTotal = kNumLowSymbols + kNumMidSymbols + (1 << kNumHighBits);
+
+const int kNumSpecSymbols = kNumLowSymbols + kNumMidSymbols;
+
+class CDecoder
+{
+  CMyBitDecoder<kNumMoveBits> m_Choice;
+  CBitTreeDecoder<kNumMoveBits, kNumLenBits>  m_LowCoder[kNumPosStatesMax];
+  CMyBitDecoder<kNumMoveBits> m_Choice2;
+  CBitTreeDecoder<kNumMoveBits, kNumMidBits>  m_MidCoder[kNumPosStatesMax];
+  CBitTreeDecoder<kNumMoveBits, kNumHighBits> m_HighCoder; 
+  UINT32 m_NumPosStates;
+public:
+  void Create(UINT32 aNumPosStates)
+    { m_NumPosStates = aNumPosStates; }
+  void Init()
+  {
+    m_Choice.Init();
+    for (UINT32 aPosState = 0; aPosState < m_NumPosStates; aPosState++)
+    {
+      m_LowCoder[aPosState].Init();
+      m_MidCoder[aPosState].Init();
+    }
+    m_Choice2.Init();
+    m_HighCoder.Init();
+  }
+  UINT32 Decode(CMyRangeDecoder *aRangeDecoder, UINT32 aPosState)
+  {
+    if(m_Choice.Decode(aRangeDecoder) == 0)
+      return m_LowCoder[aPosState].Decode(aRangeDecoder);
+    else
+    {
+      UINT32 aSymbol = kNumLowSymbols;
+      if(m_Choice2.Decode(aRangeDecoder) == 0)
+        aSymbol += m_MidCoder[aPosState].Decode(aRangeDecoder);
+      else
+      {
+        aSymbol += kNumMidSymbols;
+        aSymbol += m_HighCoder.Decode(aRangeDecoder);
+      }
+      return aSymbol;
+    }
+  }
+
+};
+
+}
+
+
+#endif