470 lines
12 KiB
C++
470 lines
12 KiB
C++
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//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1991 - 2000.
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//
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// File: BITSTM.hxx
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//
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// Contents: 'Bit streams'
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//
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// Classes: CBitStream, CWBitStream, CPBitStream, CRBitStream
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//
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// History: 03-Jul-91 KyleP Created
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// 24-Aug-92 BartoszM Rewrote it
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//
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//----------------------------------------------------------------------------
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#pragma once
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#include <bitoff.hxx>
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#include "physidx.hxx"
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#include <ci64.hxx>
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class CSmartBuffer
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{
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public:
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enum EAccessMode { eReadExisting, eWriteExisting };
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CSmartBuffer ( CPhysStorage& phStorage, EAccessMode mode );
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CSmartBuffer ( CPhysStorage& phStorage, BOOL fCreate );
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CSmartBuffer ( CPhysStorage& phStorage, ULONG numPage, EAccessMode mode, BOOL fIncrSig = TRUE );
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CSmartBuffer ( CSmartBuffer& buf, ULONG numPage );
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~CSmartBuffer ();
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ULONG PageNum() { return _numPage; }
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__forceinline ULONG* Get() { return _pBuffer + 1; }
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BOOL isEmpty() { return _pBuffer == 0; }
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void Refill ( ULONG numPage );
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ULONG* Next();
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ULONG* NextNew();
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void Free();
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BOOL IsWritable() { return _phStorage.IsWritable(); }
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WCHAR const * GetPath() { return _phStorage.GetPath(); }
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void InitSignature();
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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private:
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void CheckCorruption();
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void IncrementSig();
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CPhysStorage& _phStorage; // Source of pages
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ULONG _numPage; // current page number
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ULONG * _pBuffer; // Beginning of buffer.
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BOOL _fWritable; // Access mode for existing buffers.
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};
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//+---------------------------------------------------------------------------
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//
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// Class: CBitStream
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//
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// Purpose: Bit Stream
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//
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// History: 08-Jul-91 KyleP Created.
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// 10-Apr-94 SrikantS Added a "Refill" method to invalidate
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// the current buffer and reload during
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// master merge.
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//
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//----------------------------------------------------------------------------
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class CBitStream
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{
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public:
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__forceinline ULONG GetBits( unsigned cb);
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__forceinline ULONG* EndBuf()
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{
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Win4Assert( _pEndBuf == ( _buffer.Get() + SMARTBUF_PAGE_SIZE_IN_DWORDS ) );
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return _pEndBuf;
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}
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__forceinline void GetOffset ( BitOffset& off );
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void GetBytes(BYTE * pb, unsigned cb);
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#if CIDBG == 1
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virtual void Dump();
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unsigned PeekBit();
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#endif // CIDBG == 1
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void Seek ( const BitOffset& off );
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void Refill();
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//
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// We can remove RefillStream() and FreeStream() once NTFS supports
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// sparse file operations on parts of a file when other parts
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// of the file are mapped. This probably won't happen any time soon.
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//
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void RefillStream()
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{
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if ( !_buffer.isEmpty() )
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return;
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//
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// Re-map the stream if necessary, if unmapped for a shrink from
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// front.
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//
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Win4Assert( _buffer.IsWritable() );
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_buffer.Refill( _buffer.PageNum() );
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_pCurPos = (ULONG *) ( _oBuffer + (ULONG_PTR) _buffer.Get() );
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_pEndBuf = ( _buffer.Get() + SMARTBUF_PAGE_SIZE_IN_DWORDS );
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ciDebugOut(( DEB_BITSTM,
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"refilled stream '%ws', pCur 0x%x, pBase 0x%x, offset 0x%x, page 0x%x, this 0x%x\n",
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_buffer.GetPath(),
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_pCurPos,
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_buffer.Get(),
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_oBuffer,
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_buffer.PageNum(),
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this ));
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_oBuffer = 0;
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}
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void FreeStream()
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{
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//
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// If the stream is writable, unmap it so we can do a shrink from
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// front on the index.
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//
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if ( _buffer.IsWritable() )
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{
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if ( !_buffer.isEmpty() )
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{
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_oBuffer = (ULONG)((ULONG_PTR) _pCurPos - (ULONG_PTR) _buffer.Get());
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}
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ciDebugOut(( DEB_BITSTM,
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"tossing stream '%ws', pcur 0x%x, buf 0x%x, offset 0x%x, page 0x%x\n",
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_buffer.GetPath(), _pCurPos, _buffer.Get(), _oBuffer, _buffer.PageNum() ));
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_buffer.Free();
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_pCurPos = 0;
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}
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}
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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protected:
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CBitStream(CPhysStorage& phStorage, CSmartBuffer::EAccessMode mode );
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CBitStream(CPhysStorage& phStorage, BOOL fCreate);
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CBitStream(CPhysStorage& phStorage, const BitOffset& off,
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CSmartBuffer::EAccessMode mode, BOOL fIncrSig = TRUE);
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CBitStream(CBitStream & orig);
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__forceinline ULONG Position();
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void SetPosition(ULONG off);
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void NextDword();
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void LoadNextPage();
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void LoadNewPage();
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ULONG IGetBits (unsigned cb);
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unsigned _cbitLeftDW; // Bits left in the current DWord.
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ULONG * _pCurPos; // Current (DWord) position in buffer.
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ULONG * _pEndBuf;
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ULONG _oBuffer; // offset when buffer is freed
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CSmartBuffer _buffer;
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};
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//+---------------------------------------------------------------------------
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//
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// Class: CWBitStream
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//
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// Purpose: Writable Bit Stream
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//
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// Interface:
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//
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// History: 24-Aug-92 BartoszM Created
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// 10-Apr-94 SrikantS Added the ability to open
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// an existing stream for write
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// access during Master Merge.
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//
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//----------------------------------------------------------------------------
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class CWBitStream : public CBitStream
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{
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public:
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CWBitStream ( CPhysStorage& phStorage ): CBitStream ( phStorage, TRUE ) {}
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CWBitStream ( CPhysStorage& phStorage, const BitOffset & bitOff, BOOL fIncrSig = TRUE ) :
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CBitStream( phStorage, bitOff, CSmartBuffer::eWriteExisting, fIncrSig ) {}
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inline void PutBits(ULONG ul, unsigned cb);
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void PutBytes(const BYTE * pb, unsigned cb);
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void ZeroToEndOfPage();
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void InitSignature();
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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private:
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void NextDword();
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void IPutBits(ULONG ul, unsigned cb);
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};
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//+---------------------------------------------------------------------------
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//
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// Class: CPBitStream
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//
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// Purpose: Patch Bit Stream, used for back patching
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//
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// History: 24-Aug-92 BartoszM Created
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//
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// Notes: Seek is very cheap, since it doesn't load the page.
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// Pages are loaded on demand when writing.
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//
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//----------------------------------------------------------------------------
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class CPBitStream : public CBitStream
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{
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public:
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CPBitStream ( CPhysStorage& phStorage );
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void OverwriteBits(ULONG ul, unsigned cb);
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__forceinline void SkipBits ( unsigned delta )
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{
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_bitOff += delta;
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Win4Assert( _bitOff.Offset() < SMARTBUF_PAGE_SIZE_IN_BITS );
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}
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__forceinline void Seek ( const BitOffset& off )
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{
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_bitOff = off;
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Win4Assert( _bitOff.Offset() < SMARTBUF_PAGE_SIZE_IN_BITS );
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}
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__forceinline void GetOffset ( BitOffset& off ) {
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RtlCopyMemory( &off, &_bitOff, sizeof BitOffset );
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}
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#if CIDBG == 1
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unsigned PeekBit();
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virtual void Dump();
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#endif // CIDBG == 1
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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private:
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void IOverwriteBits(ULONG ul, unsigned cb);
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BitOffset _bitOff;
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};
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//+---------------------------------------------------------------------------
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//
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// Class: CRBitStream
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//
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// Purpose: Readable Bit Stream
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//
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// History: 24-Aug-92 BartoszM Created
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//
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//----------------------------------------------------------------------------
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class CRBitStream : public CBitStream
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{
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public:
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CRBitStream ( CPhysStorage& phStorage ): CBitStream ( phStorage, FALSE ) {}
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CRBitStream ( CPhysStorage& phStorage, const BitOffset& off )
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: CBitStream ( phStorage, off, CSmartBuffer::eReadExisting ) {}
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};
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//+---------------------------------------------------------------------------
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//
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// Member: CBitStream::GetOffset, public
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//
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// Synopsis: Returns bit offset within the index.
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//
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// Arguments: [off] -- (out) bit offset
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//
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// History: 28-Aug-92 BartoszM Created.
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//
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//----------------------------------------------------------------------------
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__forceinline void CBitStream::GetOffset ( BitOffset& off )
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{
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off.Init( _buffer.PageNum(), Position() );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CBitStream::Position, private
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//
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// Synopsis: Returns bit position within current page
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//
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// History: 28-Aug-92 BartoszM Created.
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//
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//----------------------------------------------------------------------------
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__forceinline ULONG CBitStream::Position()
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{
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return CiPtrToUlong(_pCurPos - _buffer.Get() + 1) * ULONG_BITS - _cbitLeftDW;
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CBitStream::NextDword, private
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//
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// Synopsis: Increments current dword pointer,
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// loads next page if necessary.
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//
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// History: 28-Aug-92 BartoszM Created.
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//
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//----------------------------------------------------------------------------
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__forceinline void CBitStream::NextDword()
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{
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_pCurPos++;
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_cbitLeftDW = ULONG_BITS;
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if (_pCurPos >= EndBuf())
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{
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LoadNextPage();
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}
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CWBitStream::NextDword, private
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//
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// Synopsis: Increments current dword pointer,
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// loads new page if necessary.
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//
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// History: 28-Aug-92 BartoszM Created.
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//
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//----------------------------------------------------------------------------
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__forceinline void CWBitStream::NextDword()
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{
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_pCurPos++;
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_cbitLeftDW = ULONG_BITS;
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if (_pCurPos >= EndBuf())
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{
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LoadNewPage();
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}
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CWBitStream::PutBits, public
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//
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// Synopsis: Store bits in the buffer.
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//
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// Effects: Store the [cb] low bits in [ul] beginning at the 'bit-cursor'
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//
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// Arguments: [ul] -- A DWord containing data to store.
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//
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// [cb] -- The number of bits to store.
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//
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// History: 08-Jul-91 KyleP Created.
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//
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// Notes: Bits are stored 'big-endian'.
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//
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//----------------------------------------------------------------------------
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__forceinline void CWBitStream::PutBits(ULONG ul, unsigned cb)
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{
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// ciDebugOut (( DEB_BITSTM , "PutBits %d\n", cb ));
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Win4Assert(cb != 0 && cb <= ULONG_BITS);
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//
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// The ULONG we're storing must be zero-filled at the top.
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//
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Win4Assert( (cb == ULONG_BITS) || ( (ul >> cb) == 0 ) );
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//
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// The easy case is the one where all the data fits in 1 dword.
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//
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if (cb <= _cbitLeftDW)
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{
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Win4Assert ( _pCurPos < EndBuf() );
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_cbitLeftDW -= cb;
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*_pCurPos |= (ul << _cbitLeftDW);
|
||
|
|
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
IPutBits(ul, cb);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
//+---------------------------------------------------------------------------
|
||
|
|
//
|
||
|
|
// Member: CBitStream::GetBits, public
|
||
|
|
//
|
||
|
|
// Synopsis: Retrieve bits from the buffer.
|
||
|
|
//
|
||
|
|
// Arguments: [cb] -- Count of bits to retrieve.
|
||
|
|
//
|
||
|
|
// History: 12-Jul-91 KyleP Created.
|
||
|
|
//
|
||
|
|
//----------------------------------------------------------------------------
|
||
|
|
|
||
|
|
__forceinline ULONG CBitStream::GetBits(unsigned cb)
|
||
|
|
{
|
||
|
|
// ciDebugOut (( DEB_BITSTM , "GetBits %d\n", cb ));
|
||
|
|
Win4Assert(cb != 0 && cb <= ULONG_BITS);
|
||
|
|
|
||
|
|
//
|
||
|
|
// The easy case is when the data can be extracted from the
|
||
|
|
// current dword.
|
||
|
|
//
|
||
|
|
|
||
|
|
if (cb <= _cbitLeftDW)
|
||
|
|
{
|
||
|
|
|
||
|
|
ULONG mask = 0xFFFFFFFF;
|
||
|
|
|
||
|
|
if (cb != ULONG_BITS)
|
||
|
|
{
|
||
|
|
mask = ~(mask << cb);
|
||
|
|
}
|
||
|
|
|
||
|
|
_cbitLeftDW -= cb;
|
||
|
|
return (*_pCurPos >> _cbitLeftDW) & mask;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
return IGetBits( cb );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|