Initialer Commit

CPP/7zip/Compress/ShrinkDecoder.cpp

@@ -0,0 +1,160 @@
+// ShrinkDecoder.cpp
+
+
+#include "StdAfx.h"
+
+#include <stdio.h>
+
+#include "../../../C/Alloc.h"
+
+#include "../Common/InBuffer.h"
+#include "../Common/OutBuffer.h"
+
+#include "BitlDecoder.h"
+#include "ShrinkDecoder.h"
+
+namespace NCompress {
+namespace NShrink {
+
+static const UInt32 kBufferSize = (1 << 18);
+static const unsigned kNumMinBits = 9;
+
+HRESULT CDecoder::CodeReal(ISequentialInStream *inStream, ISequentialOutStream *outStream,
+    const UInt64 * /* inSize */, const UInt64 * /* outSize */, ICompressProgressInfo *progress)
+{
+  NBitl::CBaseDecoder<CInBuffer> inBuffer;
+  COutBuffer outBuffer;
+
+  if (!inBuffer.Create(kBufferSize))
+    return E_OUTOFMEMORY;
+  inBuffer.SetStream(inStream);
+  inBuffer.Init();
+
+  if (!outBuffer.Create(kBufferSize))
+    return E_OUTOFMEMORY;
+  outBuffer.SetStream(outStream);
+  outBuffer.Init();
+
+  {
+    unsigned i;
+    for (i = 0; i < 257; i++)
+      _parents[i] = (UInt16)i;
+    for (; i < kNumItems; i++)
+      _parents[i] = kNumItems;
+    for (i = 0; i < kNumItems; i++)
+      _suffixes[i] = 0;
+  }
+
+  UInt64 prevPos = 0;
+  unsigned numBits = kNumMinBits;
+  unsigned head = 257;
+  int lastSym = -1;
+  Byte lastChar2 = 0;
+
+  for (;;)
+  {
+    UInt32 sym = inBuffer.ReadBits(numBits);
+    
+    if (inBuffer.ExtraBitsWereRead())
+      break;
+    
+    if (sym == 256)
+    {
+      sym = inBuffer.ReadBits(numBits);
+      if (sym == 1)
+      {
+        if (numBits >= kNumMaxBits)
+          return S_FALSE;
+        numBits++;
+        continue;
+      }
+      if (sym != 2)
+        return S_FALSE;
+      {
+        unsigned i;
+        for (i = 257; i < kNumItems; i++)
+          _stack[i] = 0;
+        for (i = 257; i < kNumItems; i++)
+        {
+          unsigned par = _parents[i];
+          if (par != kNumItems)
+            _stack[par] = 1;
+        }
+        for (i = 257; i < kNumItems; i++)
+          if (_stack[i] == 0)
+            _parents[i] = kNumItems;
+       
+        head = 257;
+       
+        continue;
+      }
+    }
+
+    bool needPrev = false;
+    if (head < kNumItems && lastSym >= 0)
+    {
+      while (head < kNumItems && _parents[head] != kNumItems)
+        head++;
+      if (head < kNumItems)
+      {
+        if (head == (unsigned)lastSym)
+        {
+          // we need to fix the code for that case
+          // _parents[head] is not allowed to link to itself
+          return E_NOTIMPL;
+        }
+        needPrev = true;
+        _parents[head] = (UInt16)lastSym;
+        _suffixes[head] = (Byte)lastChar2;
+        head++;
+      }
+    }
+
+    if (_parents[sym] == kNumItems)
+      return S_FALSE;
+
+    lastSym = sym;
+    unsigned cur = sym;
+    unsigned i = 0;
+    
+    while (cur >= 256)
+    {
+      _stack[i++] = _suffixes[cur];
+      cur = _parents[cur];
+    }
+    
+    _stack[i++] = (Byte)cur;
+    lastChar2 = (Byte)cur;
+
+    if (needPrev)
+      _suffixes[head - 1] = (Byte)cur;
+
+    do
+      outBuffer.WriteByte(_stack[--i]);
+    while (i);
+    
+    if (progress)
+    {
+      const UInt64 nowPos = outBuffer.GetProcessedSize();
+      if (nowPos - prevPos >= (1 << 18))
+      {
+        prevPos = nowPos;
+        const UInt64 packSize = inBuffer.GetProcessedSize();
+        RINOK(progress->SetRatioInfo(&packSize, &nowPos));
+      }
+    }
+  }
+  
+  return outBuffer.Flush();
+}
+
+STDMETHODIMP CDecoder ::Code(ISequentialInStream *inStream, ISequentialOutStream *outStream,
+    const UInt64 *inSize, const UInt64 *outSize, ICompressProgressInfo *progress)
+{
+  try { return CodeReal(inStream, outStream, inSize, outSize, progress); }
+  catch(const CInBufferException &e) { return e.ErrorCode; }
+  catch(const COutBufferException &e) { return e.ErrorCode; }
+  catch(...) { return S_FALSE; }
+}
+
+}}