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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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vc98
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mfc
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fileshrd.cpp
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C/C++ Source or Header
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1998-06-16
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// This is a part of the Microsoft Foundation Classes C++ library.
// Copyright (C) 1992-1998 Microsoft Corporation
// All rights reserved.
//
// This source code is only intended as a supplement to the
// Microsoft Foundation Classes Reference and related
// electronic documentation provided with the library.
// See these sources for detailed information regarding the
// Microsoft Foundation Classes product.
#include "stdafx.h"
#ifdef AFX_CORE4_SEG
#pragma code_seg(AFX_CORE4_SEG)
#endif
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
#define new DEBUG_NEW
////////////////////////////////////////////////////////////////////////////
// CSharedFile implementation
CSharedFile::CSharedFile(UINT nAllocFlags, UINT nGrowBytes)
: CMemFile(nGrowBytes)
{
m_nAllocFlags = nAllocFlags;
m_hGlobalMemory = NULL;
m_bAllowGrow = TRUE;
}
CSharedFile::~CSharedFile()
{
if (m_lpBuffer)
Close(); // call appropriate Close/Free
ASSERT(m_lpBuffer == NULL);
}
void CSharedFile::SetHandle(HGLOBAL hGlobalMemory, BOOL bAllowGrow)
{
ASSERT(m_hGlobalMemory == NULL); // do once only
ASSERT(m_lpBuffer == NULL); // do once only
ASSERT(m_nPosition == 0);
m_hGlobalMemory = hGlobalMemory;
m_lpBuffer = (BYTE*)::GlobalLock(m_hGlobalMemory);
m_nBufferSize = m_nFileSize = ::GlobalSize(m_hGlobalMemory);
m_bAllowGrow = bAllowGrow;
}
BYTE* CSharedFile::Alloc(DWORD nBytes)
{
ASSERT(m_hGlobalMemory == NULL); // do once only
m_hGlobalMemory = ::GlobalAlloc(m_nAllocFlags, nBytes);
if (m_hGlobalMemory == NULL)
return NULL;
return (BYTE*)::GlobalLock(m_hGlobalMemory);
}
BYTE* CSharedFile::Realloc(BYTE*, DWORD nBytes)
{
if (!m_bAllowGrow)
return NULL;
ASSERT(m_hGlobalMemory != NULL);
::GlobalUnlock(m_hGlobalMemory);
HGLOBAL hNew;
hNew = ::GlobalReAlloc(m_hGlobalMemory, nBytes, m_nAllocFlags);
if (hNew == NULL)
return NULL;
m_hGlobalMemory = hNew;
return (BYTE*)::GlobalLock(m_hGlobalMemory);
}
void CSharedFile::Free(BYTE*)
{
ASSERT(m_hGlobalMemory != NULL);
::GlobalUnlock(m_hGlobalMemory);
::GlobalFree(m_hGlobalMemory);
}
HGLOBAL CSharedFile::Detach()
{
HGLOBAL hMem;
ASSERT(m_hGlobalMemory != NULL);
hMem = m_hGlobalMemory;
m_hGlobalMemory = NULL; // detach from global handle
// re-initialize the CMemFile parts too
m_lpBuffer = NULL;
m_nBufferSize = 0;
return hMem;
}
#ifdef AFX_INIT_SEG
#pragma code_seg(AFX_INIT_SEG)
#endif
IMPLEMENT_DYNAMIC(CSharedFile, CMemFile)
////////////////////////////////////////////////////////////////////////////