4.44 beta

CPP/7zip/Compress/RangeCoder/RangeCoder.h

@@ -0,0 +1,205 @@
+// Compress/RangeCoder/RangeCoder.h
+
+#ifndef __COMPRESS_RANGECODER_H
+#define __COMPRESS_RANGECODER_H
+
+#include "../../Common/InBuffer.h"
+#include "../../Common/OutBuffer.h"
+
+namespace NCompress {
+namespace NRangeCoder {
+
+const int kNumTopBits = 24;
+const UInt32 kTopValue = (1 << kNumTopBits);
+
+class CEncoder
+{
+  UInt32 _cacheSize;
+  Byte _cache;
+public:
+  UInt64 Low;
+  UInt32 Range;
+  COutBuffer Stream;
+  bool Create(UInt32 bufferSize) { return Stream.Create(bufferSize); }
+
+  void SetStream(ISequentialOutStream *stream) { Stream.SetStream(stream); }
+  void Init()
+  {
+    Stream.Init();
+    Low = 0;
+    Range = 0xFFFFFFFF;
+    _cacheSize = 1;
+    _cache = 0;
+  }
+
+  void FlushData()
+  {
+    // Low += 1; 
+    for(int i = 0; i < 5; i++)
+      ShiftLow();
+  }
+
+  HRESULT FlushStream() { return Stream.Flush();  }
+
+  void ReleaseStream() { Stream.ReleaseStream(); }
+
+  void Encode(UInt32 start, UInt32 size, UInt32 total)
+  {
+    Low += start * (Range /= total);
+    Range *= size;
+    while (Range < kTopValue)
+    {
+      Range <<= 8;
+      ShiftLow();
+    }
+  }
+
+  void ShiftLow()
+  {
+    if ((UInt32)Low < (UInt32)0xFF000000 || (int)(Low >> 32) != 0) 
+    {
+      Byte temp = _cache;
+      do
+      {
+        Stream.WriteByte((Byte)(temp + (Byte)(Low >> 32)));
+        temp = 0xFF;
+      }
+      while(--_cacheSize != 0);
+      _cache = (Byte)((UInt32)Low >> 24);                      
+    } 
+    _cacheSize++;                               
+    Low = (UInt32)Low << 8;                           
+  }
+  
+  void EncodeDirectBits(UInt32 value, int numTotalBits)
+  {
+    for (int i = numTotalBits - 1; i >= 0; i--)
+    {
+      Range >>= 1;
+      if (((value >> i) & 1) == 1)
+        Low += Range;
+      if (Range < kTopValue)
+      {
+        Range <<= 8;
+        ShiftLow();
+      }
+    }
+  }
+
+  void EncodeBit(UInt32 size0, UInt32 numTotalBits, UInt32 symbol)
+  {
+    UInt32 newBound = (Range >> numTotalBits) * size0;
+    if (symbol == 0)
+      Range = newBound;
+    else
+    {
+      Low += newBound;
+      Range -= newBound;
+    }
+    while (Range < kTopValue)
+    {
+      Range <<= 8;
+      ShiftLow();
+    }
+  }
+
+  UInt64 GetProcessedSize() {  return Stream.GetProcessedSize() + _cacheSize + 4; }
+};
+
+class CDecoder
+{
+public:
+  CInBuffer Stream;
+  UInt32 Range;
+  UInt32 Code;
+  bool Create(UInt32 bufferSize) { return Stream.Create(bufferSize); }
+
+  void Normalize()
+  {
+    while (Range < kTopValue)
+    {
+      Code = (Code << 8) | Stream.ReadByte();
+      Range <<= 8;
+    }
+  }
+  
+  void SetStream(ISequentialInStream *stream) { Stream.SetStream(stream); }
+  void Init()
+  {
+    Stream.Init();
+    Code = 0;
+    Range = 0xFFFFFFFF;
+    for(int i = 0; i < 5; i++)
+      Code = (Code << 8) | Stream.ReadByte();
+  }
+
+  void ReleaseStream() { Stream.ReleaseStream(); }
+
+  UInt32 GetThreshold(UInt32 total)
+  {
+    return (Code) / ( Range /= total);
+  }
+
+  void Decode(UInt32 start, UInt32 size)
+  {
+    Code -= start * Range;
+    Range *= size;
+    Normalize();
+  }
+
+  UInt32 DecodeDirectBits(int numTotalBits)
+  {
+    UInt32 range = Range;
+    UInt32 code = Code;        
+    UInt32 result = 0;
+    for (int i = numTotalBits; i != 0; i--)
+    {
+      range >>= 1;
+      /*
+      result <<= 1;
+      if (code >= range)
+      {
+        code -= range;
+        result |= 1;
+      }
+      */
+      UInt32 t = (code - range) >> 31;
+      code -= range & (t - 1);
+      result = (result << 1) | (1 - t);
+
+      if (range < kTopValue)
+      {
+        code = (code << 8) | Stream.ReadByte();
+        range <<= 8; 
+      }
+    }
+    Range = range;
+    Code = code;
+    return result;
+  }
+
+  UInt32 DecodeBit(UInt32 size0, UInt32 numTotalBits)
+  {
+    UInt32 newBound = (Range >> numTotalBits) * size0;
+    UInt32 symbol;
+    if (Code < newBound)
+    {
+      symbol = 0;
+      Range = newBound;
+    }
+    else
+    {
+      symbol = 1;
+      Code -= newBound;
+      Range -= newBound;
+    }
+    Normalize();
+    return symbol;
+  }
+
+  UInt64 GetProcessedSize() {return Stream.GetProcessedSize(); }
+};
+
+}}
+
+#endif