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// ZDecoder.cpp
#include "StdAfx.h"
// #include <stdio.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 unsigned kNumMinBits = 9;
static const unsigned 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;
PackSize = 0;
if (!inBuffer.Create(kBufferSize))
return E_OUTOFMEMORY;
inBuffer.SetStream(inStream);
inBuffer.Init();
if (!outBuffer.Create(kBufferSize))
return E_OUTOFMEMORY;
outBuffer.SetStream(outStream);
outBuffer.Init();
Byte buf[kNumMaxBits + 4];
{
if (inBuffer.ReadBytes(buf, 3) < 3)
return S_FALSE;
if (buf[0] != 0x1F || buf[1] != 0x9D)
return S_FALSE;;
}
Byte prop = buf[2];
if ((prop & 0x60) != 0)
return S_FALSE;
unsigned maxbits = prop & kNumBitsMask;
if (maxbits < kNumMinBits || maxbits > kNumMaxBits)
return S_FALSE;
UInt32 numItems = 1 << maxbits;
// Speed optimization: blockSymbol can contain unused velue.
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;
UInt32 blockSymbol = ((prop & kBlockModeMask) != 0) ? 256 : ((UInt32)1 << kNumMaxBits);
unsigned numBits = kNumMinBits;
UInt32 head = (blockSymbol == 256) ? 257 : 256;
bool needPrev = false;
unsigned bitPos = 0;
unsigned numBufBits = 0;
_parents[256] = 0; // virus protection
_suffixes[256] = 0;
HRESULT res = S_OK;
for (;;)
{
if (numBufBits == bitPos)
{
numBufBits = (unsigned)inBuffer.ReadBytes(buf, numBits) * 8;
bitPos = 0;
UInt64 nowPos = outBuffer.GetProcessedSize();
if (progress && nowPos - prevPos >= (1 << 13))
{
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)
{
res = S_FALSE;
break;
}
if (symbol == blockSymbol)
{
numBufBits = bitPos = 0;
numBits = kNumMinBits;
head = 257;
needPrev = false;
continue;
}
UInt32 cur = symbol;
unsigned 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;
}
PackSize = inBuffer.GetProcessedSize();
HRESULT res2 = outBuffer.Flush();
return (res == S_OK) ? res2 : res;
}
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; }
}
bool CheckStream(const Byte *data, size_t size)
{
if (size < 3)
return false;
if (data[0] != 0x1F || data[1] != 0x9D)
return false;
Byte prop = data[2];
if ((prop & 0x60) != 0)
return false;
unsigned maxbits = prop & kNumBitsMask;
if (maxbits < kNumMinBits || maxbits > kNumMaxBits)
return false;
UInt32 numItems = 1 << maxbits;
UInt32 blockSymbol = ((prop & kBlockModeMask) != 0) ? 256 : ((UInt32)1 << kNumMaxBits);
unsigned numBits = kNumMinBits;
UInt32 head = (blockSymbol == 256) ? 257 : 256;
unsigned bitPos = 0;
unsigned numBufBits = 0;
Byte buf[kNumMaxBits + 4];
data += 3;
size -= 3;
// printf("\n\n");
for (;;)
{
if (numBufBits == bitPos)
{
unsigned num = (numBits < size) ? numBits : (unsigned)size;
memcpy(buf, data, num);
data += num;
size -= num;
numBufBits = num * 8;
bitPos = 0;
}
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)
{
// printf(" OK", symbol);
return true;
}
// printf("%3X ", symbol);
if (symbol >= head)
return false;
if (symbol == blockSymbol)
{
numBufBits = bitPos = 0;
numBits = kNumMinBits;
head = 257;
continue;
}
if (head < numItems)
{
head++;
if (head > ((UInt32)1 << numBits))
{
if (numBits < maxbits)
{
numBufBits = bitPos = 0;
numBits++;
}
}
}
}
}
}}
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