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// ShrinkDecoder.cpp
#include "StdAfx.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 << 20);
static const int 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();
UInt64 prevPos = 0;
int numBits = kNumMinBits;
UInt32 head = 257;
bool needPrev = false;
UInt32 lastSymbol = 0;
int i;
for (i = 0; i < kNumItems; i++)
_parents[i] = 0;
for (i = 0; i < kNumItems; i++)
_suffixes[i] = 0;
for (i = 0; i < 257; i++)
_isFree[i] = false;
for (; i < kNumItems; i++)
_isFree[i] = true;
for (;;)
{
UInt32 symbol = inBuffer.ReadBits(numBits);
if (inBuffer.ExtraBitsWereRead())
break;
if (_isFree[symbol])
return S_FALSE;
if (symbol == 256)
{
UInt32 symbol = inBuffer.ReadBits(numBits);
if (symbol == 1)
{
if (numBits < kNumMaxBits)
numBits++;
}
else if (symbol == 2)
{
if (needPrev)
_isFree[head - 1] = true;
for (i = 257; i < kNumItems; i++)
_isParent[i] = false;
for (i = 257; i < kNumItems; i++)
if (!_isFree[i])
_isParent[_parents[i]] = true;
for (i = 257; i < kNumItems; i++)
if (!_isParent[i])
_isFree[i] = true;
head = 257;
while (head < kNumItems && !_isFree[head])
head++;
if (head < kNumItems)
{
needPrev = true;
_isFree[head] = false;
_parents[head] = (UInt16)lastSymbol;
head++;
}
}
else
return S_FALSE;
continue;
}
UInt32 cur = symbol;
i = 0;
int corectionIndex = -1;
while (cur >= 256)
{
if (cur == head - 1)
corectionIndex = i;
_stack[i++] = _suffixes[cur];
cur = _parents[cur];
}
_stack[i++] = (Byte)cur;
if (needPrev)
{
_suffixes[head - 1] = (Byte)cur;
if (corectionIndex >= 0)
_stack[corectionIndex] = (Byte)cur;
}
while (i > 0)
outBuffer.WriteByte((_stack[--i]));
while (head < kNumItems && !_isFree[head])
head++;
if (head < kNumItems)
{
needPrev = true;
_isFree[head] = false;
_parents[head] = (UInt16)symbol;
head++;
}
else
needPrev = false;
lastSymbol = symbol;
UInt64 nowPos = outBuffer.GetProcessedSize();
if (progress != NULL && nowPos - prevPos > (1 << 18))
{
prevPos = nowPos;
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; }
}
}}
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