www.pudn.com > Wave_Src_func.zip > MemoryMapper.cpp

////////////////////////////////////////////////////////////////////////////////////////// 
// Implementation of the CMemoryMapper class. See .h for details. 
// -Vinayak Raghuvamshi 
////////////////////////////////////////////////////////////////////////////////////////// 
#include "StdAfx.h" 
#include ".\MemoryMapper.h" 
 
CMemoryMapper::CMemoryMapper(void):	m_pFileData(NULL), 
									m_dwSize(0), 
									m_hFile(INVALID_HANDLE_VALUE), 
									m_hMapOfFile(NULL), 
									m_pViewOfFile(NULL) 
{ 
} 
 
CMemoryMapper::~CMemoryMapper(void) 
{ 
	try 
	{ 
		Close(); 
	} 
	catch(...) 
	{ 
	} 
} 
 
// Opens a file for reading and creates a view of it. Fails if file does not exist. 
bool CMemoryMapper::OpenFileForRead(const TCHAR *szFile) 
{ 
	Close(); 
	m_hFile = CreateFile(	szFile, 
							GENERIC_READ, 
							FILE_SHARE_READ, 
							0, 
							OPEN_EXISTING, 
							FILE_ATTRIBUTE_NORMAL, 
							0 
						); 
 
	if(INVALID_HANDLE_VALUE == m_hFile) 
		return false; 
 
	return MapFile(m_hFile,PAGE_READONLY,FILE_MAP_READ); 
} 
 
// Opens a file mapping for writing. use if we want to modify the file 
bool CMemoryMapper::OpenFileForWrite(const TCHAR *szFile) 
{ 
	Close(); 
	m_hFile = CreateFile(	szFile, 
							GENERIC_READ|GENERIC_WRITE, 
							FILE_SHARE_READ, 
							0, 
							OPEN_EXISTING, 
							FILE_ATTRIBUTE_NORMAL, 
							0 
						); 
 
	if(INVALID_HANDLE_VALUE == m_hFile) 
		return false; 
 
	return MapFile(m_hFile,PAGE_READWRITE,FILE_MAP_READ|FILE_MAP_WRITE); 
} 
 
void CMemoryMapper::Close(void) 
{ 
	if(m_hMapOfFile) 
	{ 
		CloseHandle(m_hMapOfFile); 
		m_hMapOfFile = NULL; 
	} 
	if(m_pViewOfFile) 
	{ 
		UnmapViewOfFile(m_pViewOfFile); 
		m_pViewOfFile = NULL; 
	} 
	if(INVALID_HANDLE_VALUE != m_hFile) 
	{ 
		CloseHandle(m_hFile); 
	} 
 
	m_dwSize	= 0; 
	m_pFileData = NULL; 
} 
 
// internal open method that gets invoked by open for read and open for write.... 
bool CMemoryMapper::MapFile(const HANDLE &hFile,DWORD dwPageProtect, DWORD dwPageAccess) 
{ 
	m_dwSize = GetFileSize(hFile,0); 
	 
	if(NULL == (m_hMapOfFile = CreateFileMapping(hFile,NULL,dwPageProtect,NULL,m_dwSize,NULL))) 
	{ 
		Close(); 
		return false; 
	} 
 
	if(NULL == (m_pViewOfFile = MapViewOfFile(m_hMapOfFile,dwPageAccess,0,0,m_dwSize))) 
	{ 
		DWORD dwErr = GetLastError(); 
		Close(); 
		return false; 
	} 
 
	m_pFileData = reinterpret_cast< BYTE* >(m_pViewOfFile); 
	return true; 
}