Dragan Bojic

1
Porting XCTL from Borland C to Visual C

• Dragan Bojic
• University of Belgrade

2
The porting process

• Understanding overall structure and locating
  standard windows API elements in code
• Message handlers
• Callback functions
• Entry and exit dll procedures
• Resolving differences
• Between 16bit and 32bit Windows
• Between Borland C and Visual C
• Efficient method compile, then resolve compile
  time errors
• Resolving differences in resources (description
  of UI elements)
• Resolving runtime errors (result of differences
  in compiler calling conventions, behavior of
  library functions, etc)

3
Understanding overall structure

• Message flow in a typical Windows application

Windows kernel
Application window
Windows carries out the request to destroy the
application window Windows then sends a
WM_DESTROY Message directly to The window
function
User selects Exit from application menu
Application

WM_DESTROY
Window function
WM_QUIT
WinMain function
Application message queue
Message loop
WM_QUIT
Phrases to search for in program code
After receiving WM_QUIT, Message loop and
WinMain function terminate
4
XCLT Architecture Windows API View

• Classes for wrapping Windows API (Object Windows
  Library not used)

5
Resolving Win16-Win32 differences

• Different dll entry and exit
• 16 bit
• int FAR PASCAL LibMain(HINSTANCE
  hInstance,WORD,WORD wHeapSize,LPSTR)...
• int CALLBACK WEP(int bSystemExit)...
• 32 bit
• BOOL DllEntryPoint(HANDLE hModule,DWORD
  dwFunction,LPVOID)
• switch (dwFunction)
• case DLL_PROCESS_ATTACH...
• case DLL_PROCESS_DETACH...
• ....
• Different actual param evaluation order for some
  callback macros (WINAPI, CALLBACK functions).
  Risky scenario
• e.g. SetScrollRange(BarHandle,SB_CTL,GetBarEgde(LE
  FT),GetBarEgde(RIGHT),TRUE)
• and GetBarEdge has side effect

6
Resolving Borland-Microsoft C differences

• Categories of differences
• Preprocessor definitions
• e.g. Standard library MAXDIR to _MAX_DIR
• Declaration modifiers
• e.g. _export to __declspec(dllexport)
• Names of library functions (in some cases even .h
  file containg the function is different)
• e.g. fnsplit to _splitpath
• Completely different functions for computing
  elapsed time
• Syntax differences
• e.g. BC label is ok, VC label
• Different warning levels
• e.g. VC trunctation from double to float for
• float f 1.0 // to eliminate warning, add f to
  the end of constant

7
Resolving resource differences

• Resources descriptions of user interface
  elements (dialogs, parts of dialogs controls,
  menus,...)
• Replacing Borland Custom Controls with standard
  ones
• Borland dialogs and controls subclassed
  standard ones (they have specific message
  handling procedures to alter appearance (respond
  to paint message) or some behavior.
• Changing resource description
• CONTROL "Belichtungsregelung", -1, "BorShade",
  BSS_RGROUP BSS_CAPTION BSS_CENTER WS_CHILD
  WS_VISIBLE, 119, 93, 101, 50
• to
• GROUPBOX "Belichtungsregelung", -1, 119,
  93, 101, 50
• Changing code eliminating BWCCRegister function
  call (initialization of borland controls)

8
Resolving run time behavior differences

• Address calculation in msim.dll code 16bit model
  with segment address, and 32bit model with flat
  address
• Data sizes (16b-32b) unions risky
• Elapsed time calculation

9
Unresolved issues

• Use of inline assembly and direct access to
  hardware ports, for controlling devices
• Could work on Windows 95, but not on newer
  windows. Their device driver model is much more
  complex.