3.13

2025-12-14 22:11:38 -06:00 · 2003-12-11 00:00:00 +00:00
commit 8c1b5c7b7e
982 changed files with 118799 additions and 0 deletions
--- a/7zip/Compress/Huffman/HuffmanDecoder.h
+++ b/7zip/Compress/Huffman/HuffmanDecoder.h
@@ -0,0 +1,113 @@
+// Compress/HuffmanDecoder.h
+
+#pragma once
+
+#ifndef __COMPRESS_HUFFMANDECODER_H
+#define __COMPRESS_HUFFMANDECODER_H
+
+namespace NCompress {
+namespace NHuffman {
+
+class CDecoderException{};
+
+const UINT32 kValueTableBits = 8;
+
+template <int kNumBitsInLongestCode>
+class CDecoder
+{
+  UINT32 m_Limitits[kNumBitsInLongestCode + 1]; // m_Limitits[i] = value limit for symbols with length = i 
+  UINT32 m_Positions[kNumBitsInLongestCode + 1];   // m_Positions[i] = index in m_Symbols[] of first symbol with length = i 
+  UINT32 m_NumSymbols;
+  UINT32 *m_Symbols; // symbols: at first with len = 1 then 2, ... 15.
+  BYTE m_Lengths[1 << kValueTableBits];
+public:
+  CDecoder(UINT32 numSymbols):
+    m_NumSymbols(numSymbols)
+    { m_Symbols = new UINT32[m_NumSymbols]; }
+
+  ~CDecoder()
+    { delete []m_Symbols; }
+
+  void SetNumSymbols(UINT32 numSymbols)
+    { m_NumSymbols = numSymbols; }
+  void SetCodeLengths(const BYTE *codeLengths);
+  template <class TBitDecoder>
+  UINT32 DecodeSymbol(TBitDecoder *bitStream)
+  {
+    UINT32 numBits;
+    
+    UINT32 value = bitStream->GetValue(kNumBitsInLongestCode);
+    
+    if (value < m_Limitits[kValueTableBits])
+      numBits = m_Lengths[value >> (kNumBitsInLongestCode - kValueTableBits)];
+    else if (value < m_Limitits[10])
+      if (value < m_Limitits[9])
+        numBits = 9;
+      else
+        numBits = 10;
+    else if (value < m_Limitits[11])
+      numBits = 11;
+    else if (value < m_Limitits[12])
+      numBits = 12;
+    else 
+      for (numBits = 13; numBits < kNumBitsInLongestCode; numBits++)
+        if (value < m_Limitits[numBits])
+          break;
+    bitStream->MovePos(numBits);
+    UINT32 index = m_Positions[numBits] + 
+      ((value - m_Limitits[numBits - 1]) >> (kNumBitsInLongestCode - numBits));
+    if (index >= m_NumSymbols)
+      throw CDecoderException(); // test it
+    return m_Symbols[index];
+  }
+};
+
+
+template <int kNumBitsInLongestCode>
+void CDecoder<kNumBitsInLongestCode>::SetCodeLengths(const BYTE *codeLengths)
+{
+  int lenCounts[kNumBitsInLongestCode + 1], tmpPositions[kNumBitsInLongestCode + 1];
+  int i;
+  for(i = 1; i <= kNumBitsInLongestCode; i++)
+    lenCounts[i] = 0;
+  UINT32 symbol;
+  for (symbol = 0; symbol < m_NumSymbols; symbol++)
+  {
+    BYTE codeLength = codeLengths[symbol];
+    if (codeLength > kNumBitsInLongestCode)
+      throw CDecoderException();
+    lenCounts[codeLength]++;
+  }
+  lenCounts[0] = 0;
+  tmpPositions[0] = m_Positions[0] = m_Limitits[0] = 0;
+  UINT32 startPos = 0;
+  UINT32 index = 0;
+  const UINT32 kMaxValue = (1 << kNumBitsInLongestCode);
+  for (i = 1; i <= kNumBitsInLongestCode; i++)
+  {
+    startPos += lenCounts[i] << (kNumBitsInLongestCode - i);
+    if (startPos > kMaxValue)
+      throw CDecoderException();
+    m_Limitits[i] = startPos;
+    m_Positions[i] = m_Positions[i - 1] + lenCounts[i - 1];
+    tmpPositions[i] = m_Positions[i];
+
+    if(i <= kValueTableBits)
+    {
+      UINT32 limit = (m_Limitits[i] >> (kNumBitsInLongestCode - kValueTableBits)); // change it
+      memset(m_Lengths + index, BYTE(i), limit - index);
+      index = limit;
+    }
+  }
+
+  // if (startPos != kMaxValue)
+  //   throw CDecoderException();
+
+  for (symbol = 0; symbol < m_NumSymbols; symbol++)
+    if (codeLengths[symbol] != 0)
+      m_Symbols[tmpPositions[codeLengths[symbol]]++] = symbol;
+}
+
+}}
+
+#endif