lion-tutorial13.htm

内有一些代码

  <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ret</b> <br>
  <b>CloseMapFile endp</b> 
<p><b>end start</b> <br>
  &nbsp; 
<h3> <b>Analysis:</b></h3>
<b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
invoke CreateFile,ADDR buffer,\</b> <br>
<b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
GENERIC_READ ,\</b> <br>
<b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
0,\</b> <br>
<b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
NULL,OPEN_EXISTING,FILE_ATTRIBUTE_ARCHIVE,\</b> <br>
<b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
NULL</b> 
<p>When the user selects a file in the open file dialog, we call CreateFile to 
  open it. Note that we specify GENERIC_READ to open this file for read-only access 
  and dwShareMode is zero because we don't want some other process to modify the 
  file during our operation. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke CreateFileMapping,hFileRead,NULL,PAGE_READONLY,0,0,NULL</b> 
<p>Then we call CreateFileMapping to create a memory mapped file from the opened 
  file. CreateFileMapping has the following syntax: 
<p><b>CreateFileMapping proto hFile:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  lpFileMappingAttributes:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  flProtect:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  dwMaximumSizeHigh:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  dwMaximumSizeLow:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  lpName:DWORD</b> 
<p>You should know first that CreateFileMapping doesn't have to map the whole 
  file to memory. You can use this function to map only a part of the actual file 
  to memory. You specify the size of the memory mapped file in dwMaximumSizeHigh 
  and dwMaximumSizeLow params. If you specify the size that 's larger than the 
  actual file, the actual file will be expanded to the new size. If you want the 
  memory mapped file to be the same size as the actual file, put zeroes in both 
  params. <br>
  You can use NULL in lpFileMappingAttributes parameter to have Windows creates 
  a memory mapped file with default security attributes. <br>
  flProtect defines the protection desired for the memory mapped file. In our 
  example, we use PAGE_READONLY to allow only read operation on the memory mapped 
  file. Note that this attribute must not contradict the attribute used in CreateFile 
  else CreateFileMapping will fail. <br>
  lpName points to the name of the memory mapped file. If you want to share this 
  file with other process, you must provide it a name. But in our example, our 
  process is the only one that uses this file so we ignore this parameter. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  mov&nbsp;&nbsp;&nbsp;&nbsp; eax,OFFSET buffer</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  movzx&nbsp; edx,ofn.nFileOffset</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  add&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; eax,edx</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke SetWindowText,hWnd,eax</b> 
<p>If CreateFileMapping is successful, we change the window caption to the name 
  of the opened file. The filename with full path is stored in buffer, we want 
  to display only the filename in the caption so we must add the value of nFileOffset 
  member of the OPENFILENAME structure to the address of buffer. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke EnableMenuItem,hMenu,IDM_OPEN,MF_GRAYED</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke EnableMenuItem,hMenu,IDM_SAVE,MF_ENABLED</b> 
<p>As a precaution, we don't want the user to open multiple files at once, so 
  we gray out the Open menu item and enable the Save menu item. EnableMenuItem 
  is used to change the attribute of menu item. <br>
  After this, we wait for the user to select File/Save as menu item or close our 
  program. If the user chooses to close our program, we must close the memory 
  mapped file and the actual file like the code below: 
<p><b>&nbsp;&nbsp;&nbsp; .ELSEIF uMsg==WM_DESTROY</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; .if hMapFile!=0</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; call CloseMapFile</b> 
  <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; .endif</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; invoke PostQuitMessage,NULL</b> 
<p>In the above code snippet, when the window procedure receives the WM_DESTROY 
  message, it checks the value of hMapFile first whether it is zero or not. If 
  it's not zero, it calls CloseMapFile function which contains the following code: 
<p><b>CloseMapFile PROC</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; invoke CloseHandle,hMapFile</b> 
  <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; mov&nbsp;&nbsp;&nbsp; hMapFile,0</b> 
  <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; invoke CloseHandle,hFileRead</b> 
  <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ret</b> <br>
  <b>CloseMapFile endp</b> 
<p>CloseMapFile closes the memory mapped file and the actual file so that there 
  'll be no resource leakage when our program exits to Windows. <br>
  If the user chooses to save that data to another file, the program presents 
  him with a save as dialog box. After he types in the name of the new file, the 
  file is created by CreateFile function. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke MapViewOfFile,hMapFile,FILE_MAP_READ,0,0,0</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  mov pMemory,eax</b> 
<p>Immediately after the output file is created, we call MapViewOfFile to map 
  the desired portion of the memory mapped file into memory. This function has 
  the following syntax: 
<p><b>MapViewOfFile proto hFileMappingObject:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  dwDesiredAccess:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  dwFileOffsetHigh:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  dwFileOffsetLow:DWORD,\</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  dwNumberOfBytesToMap:DWORD</b> 
<p><b>dwDesiredAccess</b> specifies what operation we want to do to the file. 
  In our example, we want to read the data only so we use FILE_MAP_READ. <br>
  <b>dwFileOffsetHigh</b> and <b>dwFileOffsetLow</b>specify the starting file 
  offset of the file portion that you want to map into memory. In our case, we 
  want to read in the whole file so we start mapping from offset 0 onwards. <br>
  <b>dwNumberOfBytesToMap</b> specifies the number of bytes to map into memory. 
  If you want to map the whole file (specified by CreateFileMapping), pass 0 to 
  MapViewOfFile. <br>
  After calling MapViewOfFile, the desired portion is loaded into memory. You'll 
  be given the pointer to the memory block that contains the data from the file. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke GetFileSize,hFileRead,NULL</b> 
<p>Find out how large the file is. The file size is returned in eax. If the file 
  is larger than 4 GB,&nbsp; the high DWORD of the file size is stored in FileSizeHighWord. 
  Since we don't expect to handle such large file, we can ignore it. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke WriteFile,hFileWrite,pMemory,eax,ADDR SizeWritten,NULL</b> 
<p>Write the data that is mapped into memory into the output file. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke UnmapViewOfFile,pMemory</b> 
<p>When we're through with the input file, unmap it from memory. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  call&nbsp;&nbsp; CloseMapFile</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke CloseHandle,hFileWrite</b> 
<p>And close all the files. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke SetWindowText,hWnd,ADDR AppName</b> 
<p>Restore the original caption text. 
<p><b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke EnableMenuItem,hMenu,IDM_OPEN,MF_ENABLED</b> <br>
  <b>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  invoke EnableMenuItem,hMenu,IDM_SAVE,MF_GRAYED</b> 
<p>Enable the Open menu item and gray out the Save As menu item. 
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