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// ZDecoder.cpp
#include "StdAfx.h"
#include "../../../C/Alloc.h"
#include "../Common/InBuffer.h"
#include "../Common/OutBuffer.h"
#include "ZDecoder.h"
namespace NCompress {
namespace NZ {
static const UInt32 kBufferSize = (1 << 20);
static const Byte kNumBitsMask = 0x1F;
static const Byte kBlockModeMask = 0x80;
static const int kNumMinBits = 9;
static const int kNumMaxBits = 16;
void CDecoder::Free()
{
MyFree(_parents); _parents = 0;
MyFree(_suffixes); _suffixes = 0;
MyFree(_stack); _stack = 0;
}
CDecoder::~CDecoder() { Free(); }
HRESULT CDecoder::CodeReal(ISequentialInStream *inStream, ISequentialOutStream *outStream,
const UInt64 * /* inSize */, const UInt64 * /* outSize */, ICompressProgressInfo *progress)
{
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();
int maxbits = _properties & kNumBitsMask;
if (maxbits < kNumMinBits || maxbits > kNumMaxBits)
return S_FALSE;
UInt32 numItems = 1 << maxbits;
bool blockMode = ((_properties & kBlockModeMask) != 0);
if (maxbits != _numMaxBits || _parents == 0 || _suffixes == 0 || _stack == 0)
{
Free();
_parents = (UInt16 *)MyAlloc(numItems * sizeof(UInt16)); if (_parents == 0) return E_OUTOFMEMORY;
_suffixes = (Byte *)MyAlloc(numItems * sizeof(Byte)); if (_suffixes == 0) return E_OUTOFMEMORY;
_stack = (Byte *)MyAlloc(numItems * sizeof(Byte)); if (_stack == 0) return E_OUTOFMEMORY;
_numMaxBits = maxbits;
}
UInt64 prevPos = 0;
int numBits = kNumMinBits;
UInt32 head = blockMode ? 257 : 256;
bool needPrev = false;
unsigned bitPos = 0;
unsigned numBufBits = 0;
Byte buf[kNumMaxBits + 4];
_parents[256] = 0; // virus protection
_suffixes[256] = 0;
for (;;)
{
if (numBufBits == bitPos)
{
numBufBits = (unsigned)inBuffer.ReadBytes(buf, numBits) * 8;
bitPos = 0;
UInt64 nowPos = outBuffer.GetProcessedSize();
if (progress != NULL && nowPos - prevPos >= (1 << 18))
{
prevPos = nowPos;
UInt64 packSize = inBuffer.GetProcessedSize();
RINOK(progress->SetRatioInfo(&packSize, &nowPos));
}
}
unsigned bytePos = bitPos >> 3;
UInt32 symbol = buf[bytePos] | ((UInt32)buf[bytePos + 1] << 8) | ((UInt32)buf[bytePos + 2] << 16);
symbol >>= (bitPos & 7);
symbol &= (1 << numBits) - 1;
bitPos += numBits;
if (bitPos > numBufBits)
break;
if (symbol >= head)
return S_FALSE;
if (blockMode && symbol == 256)
{
numBufBits = bitPos = 0;
numBits = kNumMinBits;
head = 257;
needPrev = false;
continue;
}
UInt32 cur = symbol;
int i = 0;
while (cur >= 256)
{
_stack[i++] = _suffixes[cur];
cur = _parents[cur];
}
_stack[i++] = (Byte)cur;
if (needPrev)
{
_suffixes[head - 1] = (Byte)cur;
if (symbol == head - 1)
_stack[0] = (Byte)cur;
}
do
outBuffer.WriteByte((_stack[--i]));
while (i > 0);
if (head < numItems)
{
needPrev = true;
_parents[head++] = (UInt16)symbol;
if (head > ((UInt32)1 << numBits))
{
if (numBits < maxbits)
{
numBufBits = bitPos = 0;
numBits++;
}
}
}
else
needPrev = false;
}
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; }
}
STDMETHODIMP CDecoder::SetDecoderProperties2(const Byte *data, UInt32 size)
{
if (size < 1)
return E_INVALIDARG;
_properties = data[0];
return S_OK;
}
}}
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