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