Q84071: SAMPLE: WNBDemo.exe Uses NetBIOS Under Microsoft Windows
Article: Q84071
Product(s): Microsoft Windows Device Driver Kit
Version(s): 3.0,3.1
Operating System(s):
Keyword(s): kbfile kbnetwork kbsample kbNetBIOS kbGrpDSNet
Last Modified: 23-JUL-2001
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The information in this article applies to:
- Microsoft Windows Device Development Kit (DDK) for Windows, versions 3.0, 3.1
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SUMMARY
=======
WNBDemo.exe is a sample that contains sample source code and additional
documentation for NetBIOS under Windows. In the Microsoft Windows operating
system, an application can use NetBIOS functions in every Windows mode (real,
standard, or 386 enhanced). However, the application must conform to some rules,
which are briefly discussed in the text below.
MORE INFORMATION
================
The following file is available for download from the Microsoft Download
Center:
WNBDemo.exe
(http://download.microsoft.com/download/platformsdk/sample97/3.1/W31/EN-US/WNBDemo.exe)
For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft used the most current virus detection software available on the date of
posting to scan this file for viruses. Once posted, the file is housed on secure
servers that prevent any unauthorized changes to the file.
NOTE: Microsoft C Optimizing Compiler version 6.0 or later and Microsoft Macro
Assembler (MASM) version 5.1 or later are required to build the source code in
WNBDEMO.
Windows provides access to NetBIOS through the NetBIOSCall function. This
function is equivalent to issuing Interrupt 5Ch under MS-DOS. Although it is
legal to call Interrupt 5Ch directly from within Windows, this is not the
recommended practice; use NetBIOSCall.
An application should call the NetBIOSCall() function from assembly language to
ensure that the registers are preserved for the call. The following is a short
stub function that can be used to issue NetBIOS calls under Windows:
extrn NETBIOSCALL : FAR
extrn DOS3CALL : FAR
assume cs: _TEXT
_TEXT SEGMENT WORD PUBLIC 'CODE'
; WORD FAR PASCAL nbNetBIOS(LPNCB lpNCB)
PUBLIC nbNetBIOS
nbNetBIOS proc FAR
push bp ; save bp
mov bp, sp ; sp into bp for stack access
push es ; save es
push bx ; save bx
mov es, word ptr [bp + 8] ; put HIWORD into es
mov bx, word ptr [bp + 6] ; put LOWORD into bx
call NetBIOSCall ; shazam!
xor ah, ah
mov al, byte ptr es:[bx + 1] ; return the return code
pop bx ; restore bx
pop es ; restore es
mov sp, bp ; restore sp
pop bp ; restore bp
ret 4 ; return to caller
; fix-up stack
nbNetBIOS endp
_TEXT ENDS
END
This function takes a FAR pointer to an initialized network control block (NCB)
and returns the NCB's return code from the NetBIOS driver.
Unlike MS-DOS, Windows also has special memory requirements for NCBs and post
routines. The general rule of thumb is to fix the NCBs and post routines in
memory as much as possible to prevent paging, banking, or other time-consuming
operations during the time that the application uses the NCBs and post
routines.
For post routines, all code and data segments used by the routine must be placed
into FIXED segments of a dynamic-link library (DLL). This causes the segments to
be page locked, not banked, and to have other attributes appropriate to the mode
in which Windows is running. Because the FIXED keyword is ignored for
applications, this code must be placed in a DLL.
Remember that the post routine may call only the PostMessage(), PostAppMessage(),
and NetBIOSCall() functions; it cannot call any other functions in Windows. To
call the nbNetBIOS function given above from the post routine, nbNetBIOS must be
placed into a FIXED segment of a DLL and the function must be reentrant.
NCBs should be allocated such that they are also page locked, not banked, and
have other attributes appropriate to the mode in which Windows is running. The
easiest way to do this is to use GlobalAlloc() to allocate memory for the NCB
either as GMEM_FIXED or to call the GlobalWire() function to move the memory as
low as possible in the address space (followed by a call to GlobalPageLock() in
386 enhanced mode). If the memory is allocated from a DLL with the GMEM_FIXED
flag, then the memory will also be page locked--this is true only for
allocations from DLLs.
As stated above, for further information, refer to the WNBDEMO.exe in the
Microsoft Download Center.
REFERENCES
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"An Introduction to Network Programming Using the NetBIOS Interface," by Alok
Sinha and Ray Patch, March-April 1992 Microsoft Systems Journal
Additional query words:
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Keywords : kbfile kbnetwork kbsample kbNetBIOS kbGrpDSNet
Technology : kbAudDeveloper kbWin3xSearch kbWinDDKSearch kbWinDDK300 kbWinDDK310
Version : :3.0,3.1
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