129 lines
3.2 KiB
C++
129 lines
3.2 KiB
C++
//+---------------------------------------------------------------------------
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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: DYNSTRM.HXX
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//
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// Contents: Dynamicly growing memory mapped versioned stream
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//
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// History: 18-May-93 BartoszM Created
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// 07-Dec-93 DwightKr Added Shrink() method
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// 28-Jul-97 SitaramR Added sequential read/write
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//
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//----------------------------------------------------------------------------
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#pragma once
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#include <pmmstrm.hxx>
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//
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// The stream header contains the following numbers
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//
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// Version
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// Count of items
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// Data size in bytes
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//
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// followed by items occupying data_size bytes
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// and possibly some slack space for growth
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//
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// |-----|++++++++++++++|---------|
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// HDR ^ ^ ^
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// +-- data size -+ |
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// +----- avail size -------+
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//
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// The size of the stream is always kept a multiple
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// of COMMON_PAGE_SIZE
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class PStorage;
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class CDynStream
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{
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enum
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{
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HEADER_VERSION = 0,
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HEADER_DIRTY = 1,
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HEADER_COUNT = 2,
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HEADER_DATASIZE = 3,
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HEADER_SIZE = 4 * sizeof(ULONG)
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};
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public:
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CDynStream(PMmStream* pStream);
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CDynStream();
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~CDynStream();
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void Init ( PMmStream* pStream ) { _pStream = pStream; }
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BOOL CheckVersion ( PStorage& storage, ULONG version, BOOL fIsReadOnly );
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BOOL Ok() { return _pStream->Ok(); }
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BYTE* Get() { return (BYTE*)_bufStream.Get() + HEADER_SIZE; }
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void Grow( PStorage& storage, ULONG newDataSize );
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void Shrink( PStorage& storage, ULONG newDataSize );
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BOOL isWritable() { return _pStream->isWritable(); }
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ULONG Version()
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{
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Win4Assert( 0 == HEADER_VERSION );
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return *(ULONG*)_bufStream.Get();
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}
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void Flush();
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BOOL MarkDirty();
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void MarkClean()
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{
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*((ULONG *) _bufStream.Get() + HEADER_DIRTY) = FALSE;
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}
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BOOL IsDirty()
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{
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return *((ULONG *) _bufStream.Get() + HEADER_DIRTY);
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}
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ULONG Count()
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{
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return *((ULONG*)_bufStream.Get() + HEADER_COUNT);
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}
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ULONG DataSize()
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{
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return *((ULONG*)_bufStream.Get() + HEADER_DATASIZE);
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}
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void SetVersion( ULONG version)
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{
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Win4Assert( 0 == HEADER_VERSION );
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*((ULONG *) _bufStream.Get()) = version;
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}
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void SetCount( ULONG count)
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{
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*((ULONG *) _bufStream.Get() + HEADER_COUNT) = count;
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}
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void SetDataSize ( ULONG size)
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{
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*((ULONG *) _bufStream.Get() + HEADER_DATASIZE) = size;
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}
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ULONG AvailSize() const
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{
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return _bufStream.Size() - HEADER_SIZE;
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}
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void InitializeForRead();
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void InitializeForWrite( ULONG cbSize );
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ULONG Read( void *pBuf, ULONG cbToRead );
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void Write( void *pBuf, ULONG cbToWrite );
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private:
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PMmStream* _pStream;
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CMmStreamBuf _bufStream;
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BYTE * _pCurPos; // Pointer for reading, writing
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BYTE * _pStartPos; // Start pointer for reading, writing
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ULONG _ulDataSize; // Size of persistent stream
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};
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