o cleanup

tools/bsnes/reader/jma/rngcoder.h

@@ -0,0 +1,143 @@
+/*
+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 version 2.1 as published by the Free Software Foundation.
+
+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 __COMPRESSION_RANGECODER_H
+#define __COMPRESSION_RANGECODER_H
+
+#include "inbyte.h"
+
+namespace NCompression {
+namespace NArithmetic {
+
+const UINT32 kNumTopBits = 24;
+const UINT32 kTopValue = (1 << kNumTopBits);
+
+class CRangeDecoder
+{
+public:
+  NStream::CInByte m_Stream;
+  UINT32 m_Range;
+  UINT32 m_Code;
+  UINT32 m_Word;
+  void Normalize()
+  {
+    while (m_Range < kTopValue)
+    {
+      m_Code = (m_Code << 8) | m_Stream.ReadByte();
+      m_Range <<= 8;
+    }
+  }
+
+  void Init(ISequentialInStream *aStream)
+  {
+    m_Stream.Init(aStream);
+    m_Code = 0;
+    m_Range = UINT32(-1);
+    for(int i = 0; i < 5; i++)
+      m_Code = (m_Code << 8) | m_Stream.ReadByte();
+  }
+
+  UINT32 GetThreshold(UINT32 aTotal)
+  {
+    return (m_Code) / ( m_Range /= aTotal);
+  }
+
+  void Decode(UINT32 aStart, UINT32 aSize, UINT32 aTotal)
+  {
+    m_Code -= aStart * m_Range;
+    m_Range *= aSize;
+    Normalize();
+  }
+
+  /*
+  UINT32 DecodeDirectBitsDiv(UINT32 aNumTotalBits)
+  {
+    m_Range >>= aNumTotalBits;
+    UINT32 aThreshold = m_Code / m_Range;
+    m_Code -= aThreshold * m_Range;
+
+    Normalize();
+    return aThreshold;
+  }
+
+  UINT32 DecodeDirectBitsDiv2(UINT32 aNumTotalBits)
+  {
+    if (aNumTotalBits <= kNumBottomBits)
+      return DecodeDirectBitsDiv(aNumTotalBits);
+    UINT32 aResult = DecodeDirectBitsDiv(aNumTotalBits - kNumBottomBits) << kNumBottomBits;
+    return (aResult | DecodeDirectBitsDiv(kNumBottomBits));
+  }
+  */
+
+  UINT32 DecodeDirectBits(UINT32 aNumTotalBits)
+  {
+    UINT32 aRange = m_Range;
+    UINT32 aCode = m_Code;
+    UINT32 aResult = 0;
+    for (UINT32 i = aNumTotalBits; i > 0; i--)
+    {
+      aRange >>= 1;
+      /*
+      aResult <<= 1;
+      if (aCode >= aRange)
+      {
+        aCode -= aRange;
+        aResult |= 1;
+      }
+      */
+      UINT32 t = (aCode - aRange) >> 31;
+      aCode -= aRange & (t - 1);
+      // aRange = aRangeTmp + ((aRange & 1) & (1 - t));
+      aResult = (aResult << 1) | (1 - t);
+
+      if (aRange < kTopValue)
+      {
+        aCode = (aCode << 8) | m_Stream.ReadByte();
+        aRange <<= 8;
+      }
+    }
+    m_Range = aRange;
+    m_Code = aCode;
+    return aResult;
+  }
+
+  UINT32 DecodeBit(UINT32 aSize0, UINT32 aNumTotalBits)
+  {
+    UINT32 aNewBound = (m_Range >> aNumTotalBits) * aSize0;
+    UINT32 aSymbol;
+    if (m_Code < aNewBound)
+    {
+      aSymbol = 0;
+      m_Range = aNewBound;
+    }
+    else
+    {
+      aSymbol = 1;
+      m_Code -= aNewBound;
+      m_Range -= aNewBound;
+    }
+    Normalize();
+    return aSymbol;
+  }
+
+  UINT64 GetProcessedSize() {return m_Stream.GetProcessedSize(); }
+};
+
+}}
+
+#endif