136 lines
3.5 KiB
C++
136 lines
3.5 KiB
C++
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//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1992 - 1998
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//
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// File: mmscbuf.cxx
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//
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// Contents: Memory Mapped Stream buffer for consecutive buffer mapping
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//
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// Classes: CMmStreamConsecBuf
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//
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// History: 22-Jul-93 AmyA Created
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//
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//----------------------------------------------------------------------------
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#include <pch.cxx>
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#pragma hdrstop
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#include <mmscbuf.hxx>
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//+-------------------------------------------------------------------------
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//
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// Member: CMmStreamConsecBuf::CMmStreamConsecBuf, public
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//
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// Synopsis: Constructor
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//
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// History: 22-Jul-93 AmyA Created
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//
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//--------------------------------------------------------------------------
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CMmStreamConsecBuf::CMmStreamConsecBuf()
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: _pMmStream(0)
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{
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_liOffset.QuadPart = 0;
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}
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//+-------------------------------------------------------------------------
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//
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// Member: CMmStreamConsecBuf::Map, public
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//
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// Synopsis: Map next consecutive part of file
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//
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// Arguments: [cb] -- size of the mapped area
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//
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// History: 22-Jul-93 AmyA Created
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//
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//--------------------------------------------------------------------------
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void CMmStreamConsecBuf::Map( ULONG cb )
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{
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Win4Assert( 0 != _pMmStream );
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if ( Get() != 0 )
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_pMmStream->Unmap( *this );
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LARGE_INTEGER liNewOffset;
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LARGE_INTEGER liStreamSize={_pMmStream->SizeLow(), _pMmStream->SizeHigh()};
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liNewOffset.QuadPart = cb + _liOffset.QuadPart;
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if ( liNewOffset.QuadPart > liStreamSize.QuadPart )
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{
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cb = (ULONG)(liStreamSize.QuadPart - _liOffset.QuadPart);
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liNewOffset = liStreamSize;
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}
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_pMmStream->Map( *this,
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cb,
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_liOffset.LowPart,
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_liOffset.HighPart );
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_liOffset = liNewOffset;
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}
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//+-------------------------------------------------------------------------
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//
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// Member: CMmStreamConsecBuf::Init, public
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//
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// Synopsis: Initizializes CMmStreamConsecBuf
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//
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// Arguments: [pMmStream] -- pointer to the CMmStream from which to fill
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// the buffer
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//
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// History: 22-Jul-93 AmyA Created
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//
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//--------------------------------------------------------------------------
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void CMmStreamConsecBuf::Init( PMmStream * pMmStream )
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{
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_pMmStream = pMmStream;
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_liOffset.QuadPart = 0;
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}
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//+-------------------------------------------------------------------------
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//
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// Member: CMmStreamConsecBuf::Rewind, public
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//
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// Synopsis: Rewind file to beginning.
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//
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// History: 13-Dec-93 AmyA Created
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//
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//--------------------------------------------------------------------------
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void CMmStreamConsecBuf::Rewind()
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{
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if ( 0 != Get() )
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{
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Win4Assert( 0 != _pMmStream );
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_pMmStream->Unmap( *this );
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}
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_liOffset.QuadPart = 0;
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}
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//+-------------------------------------------------------------------------
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//
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// Member: CMmStreamConsecBuf::Eof, public
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//
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// Synopsis: Returns whether end of file has been hit
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//
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// Returns: FALSE if there is still more file to be mapped. TRUE
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// otherwise.
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//
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// History: 22-Jul-93 AmyA Created
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//
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//--------------------------------------------------------------------------
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BOOL CMmStreamConsecBuf::Eof()
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{
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Win4Assert( 0 != _pMmStream );
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return( ( (ULONG) _liOffset.HighPart == _pMmStream->SizeHigh() ) &&
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( _liOffset.LowPart == _pMmStream->SizeLow() ) );
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}
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