4.20

7zip/Compress/BWT/Mtf8.h

@@ -0,0 +1,140 @@
+// Mtf8.h
+
+#ifndef __MTF8_H
+#define __MTF8_H
+
+#include "Common/Types.h"
+
+namespace NCompress {
+
+class CMtf8Encoder
+{
+public:
+  Byte Buffer[256];
+  int FindAndMove(Byte v)
+  {
+    int pos;
+    for (pos = 0; Buffer[pos] != v; pos++);
+    int resPos = pos;
+    for (; pos >= 8; pos -= 8)
+    {
+      Buffer[pos] = Buffer[pos - 1];
+      Buffer[pos - 1] = Buffer[pos - 2];
+      Buffer[pos - 2] = Buffer[pos - 3];
+      Buffer[pos - 3] = Buffer[pos - 4];
+      Buffer[pos - 4] = Buffer[pos - 5];
+      Buffer[pos - 5] = Buffer[pos - 6];
+      Buffer[pos - 6] = Buffer[pos - 7];
+      Buffer[pos - 7] = Buffer[pos - 8];
+    }
+    for (; pos > 0; pos--)
+      Buffer[pos] = Buffer[pos - 1];
+    Buffer[0] = v;
+    return resPos;
+  }
+};
+
+class CMtf8Decoder
+{
+public:
+  Byte Buffer[256];
+  void Init(int size) {};
+  Byte GetHead() const { return Buffer[0]; }
+  Byte GetAndMove(int pos)
+  {
+    Byte res = Buffer[pos];
+    for (; pos >= 8; pos -= 8)
+    {
+      Buffer[pos] = Buffer[pos - 1];
+      Buffer[pos - 1] = Buffer[pos - 2];
+      Buffer[pos - 2] = Buffer[pos - 3];
+      Buffer[pos - 3] = Buffer[pos - 4];
+      Buffer[pos - 4] = Buffer[pos - 5];
+      Buffer[pos - 5] = Buffer[pos - 6];
+      Buffer[pos - 6] = Buffer[pos - 7];
+      Buffer[pos - 7] = Buffer[pos - 8];
+    }
+    for (; pos > 0; pos--)
+      Buffer[pos] = Buffer[pos - 1];
+    Buffer[0] = res;
+    return res;
+  }
+};
+
+/*
+const int kSmallSize = 64;
+class CMtf8Decoder
+{
+  Byte SmallBuffer[kSmallSize];
+  int SmallSize;
+  Byte Counts[16];
+  int Size;
+public:
+  Byte Buffer[256];
+
+  Byte GetHead() const 
+  { 
+    if (SmallSize > 0)
+      return SmallBuffer[kSmallSize - SmallSize];
+    return Buffer[0];
+  }
+
+  void Init(int size) 
+  { 
+    Size = size; 
+    SmallSize = 0; 
+    for (int i = 0; i < 16; i++)
+    {
+      Counts[i] = ((size >= 16) ? 16 : size);
+      size -= Counts[i];
+    }
+  }
+
+  Byte GetAndMove(int pos)
+  {
+    if (pos < SmallSize)
+    {
+      Byte *p = SmallBuffer + kSmallSize - SmallSize;
+      Byte res = p[pos];
+      for (; pos > 0; pos--)
+        p[pos] = p[pos - 1];
+      SmallBuffer[kSmallSize - SmallSize] = res;
+      return res;
+    }
+    if (SmallSize == kSmallSize)
+    {
+      int i = Size - 1;
+      int g = 16;
+      do
+      {
+        g--;
+        int offset = (g << 4);
+        for (int t = Counts[g] - 1; t >= 0; t--, i--)
+          Buffer[i] = Buffer[offset + t];
+      }
+      while(g != 0);
+      
+      for (i = kSmallSize - 1; i >= 0; i--)
+        Buffer[i] = SmallBuffer[i];
+      Init(Size);
+    }
+    pos -= SmallSize;
+    int g;
+    for (g = 0; pos >= Counts[g]; g++)
+      pos -= Counts[g];
+    int offset = (g << 4);
+    Byte res = Buffer[offset + pos];
+    for (pos; pos < 16 - 1; pos++)
+      Buffer[offset + pos] = Buffer[offset + pos + 1];
+    
+    SmallSize++;
+    SmallBuffer[kSmallSize - SmallSize] = res;
+
+    Counts[g]--;
+    return res;
+  }
+};
+*/
+
+}
+#endif