o cleanup

tools/bsnes/reader/jma/aribitcd.h

@@ -0,0 +1,73 @@
+#ifndef __COMPRESSION_BITCODER_H
+#define __COMPRESSION_BITCODER_H
+
+#include "rngcoder.h"
+
+namespace NCompression {
+namespace NArithmetic {
+
+const int kNumBitModelTotalBits  = 11;
+const UINT32 kBitModelTotal = (1 << kNumBitModelTotalBits);
+
+const int kNumMoveReducingBits = 2;
+
+/////////////////////////////
+// CBitModel
+
+template <int aNumMoveBits>
+class CBitModel
+{
+public:
+  UINT32 m_Probability;
+  void UpdateModel(UINT32 aSymbol)
+  {
+    /*
+    m_Probability -= (m_Probability + ((aSymbol - 1) & ((1 << aNumMoveBits) - 1))) >> aNumMoveBits;
+    m_Probability += (1 - aSymbol) << (kNumBitModelTotalBits - aNumMoveBits);
+    */
+    if (aSymbol == 0)
+      m_Probability += (kBitModelTotal - m_Probability) >> aNumMoveBits;
+    else
+      m_Probability -= (m_Probability) >> aNumMoveBits;
+  }
+public:
+  void Init() { m_Probability = kBitModelTotal / 2; }
+};
+
+template <int aNumMoveBits>
+class CBitDecoder: public CBitModel<aNumMoveBits>
+{
+public:
+  UINT32 Decode(CRangeDecoder *aRangeDecoder)
+  {
+    UINT32 aNewBound = (aRangeDecoder->m_Range >> kNumBitModelTotalBits) * CBitModel<aNumMoveBits>::m_Probability;
+    if (aRangeDecoder->m_Code < aNewBound)
+    {
+      aRangeDecoder->m_Range = aNewBound;
+      CBitModel<aNumMoveBits>::m_Probability += (kBitModelTotal - CBitModel<aNumMoveBits>::m_Probability) >> aNumMoveBits;
+      if (aRangeDecoder->m_Range < kTopValue)
+      {
+        aRangeDecoder->m_Code = (aRangeDecoder->m_Code << 8) | aRangeDecoder->m_Stream.ReadByte();
+        aRangeDecoder->m_Range <<= 8;
+      }
+      return 0;
+    }
+    else
+    {
+      aRangeDecoder->m_Range -= aNewBound;
+      aRangeDecoder->m_Code -= aNewBound;
+      CBitModel<aNumMoveBits>::m_Probability -= (CBitModel<aNumMoveBits>::m_Probability) >> aNumMoveBits;
+      if (aRangeDecoder->m_Range < kTopValue)
+      {
+        aRangeDecoder->m_Code = (aRangeDecoder->m_Code << 8) | aRangeDecoder->m_Stream.ReadByte();
+        aRangeDecoder->m_Range <<= 8;
+      }
+      return 1;
+    }
+  }
+};
+
+}}
+
+
+#endif