OpenEuphoria

1. Low-level Windows wrapper

• Posted by jmduro Dec 26, 2015
• 1465 views

I have uploaded on RDS site a low-level windows wrapper based on the way Bernie Ryan built his w32engin: http://rapideuphoria.com/windows2.zip. I could not understand why wrapping could not refer to Windows original types. When moving fom 32-bit to 64-bit, a lot of functions don't work anymore because some types have different sizes. If you lost information about the original types, you are getting lost. So I found a way to always refer to original types to keep this information and allocate memory according to the architecture. This way, the same function should run with 32-bit and 64-bit interpreter without any change. This could not have been done without the help of Andreas Wagner and Matt Lewis' work.

It is not perfect: I was not able to deal correctly with 64-bit callbacks. However, it is a good basis to develop high-level libraries. Many thousands windows functions are wrapped. Windows types keep their original name with minor modifications:

• "unsigned char" becomes "unsigned_char"
• char* becomes pchar
• INT** becomes PPINT

The P prefix for a pointer, PP for pointer of pointer, and so on. When dealing with structures, user can rely on some functions:

• setParams(pointer, input, definition) fills a structure defined by "definition" at position "p" in memory (pointer) with content given by "input"
• getParams(pointer, definition) does the opposite
• getStructureLength(definition) gives the size of a structure

As with w32engin and WinLib, only functions that are really used are loaded into memory (handle != 0).

dirdlg3.exw gives an example of calling.

function dirDlg(sequence title, sequence default="", atom flags=1+16+64) 
 
  -- BROWSEINFO structure 
  sequence browse_info = {HWND,PCIDLIST_ABSOLUTE,LPTSTR,LPCTSTR,UINT,BFFCALLBACK,LPARAM,int} 
 
  -- allocate memory according to the architecture (32-bit or 64-bit) 
  integer lg = getStructureLength(browse_info) 
  atom BrowseInfo = allocate(lg) 
 
  -- fill the structure 
  atom szDispName=allocate(MAX_PATH) 
  for i=0 to MAX_PATH-1 do poke(szDispName+i,0) end for 
  atom sztitle=allocate_string(title) 
  atom startdir=allocate_string(default) 
  setParams(BrowseInfo, {WinHwnd,0,szDispName,sztitle,flags,call_back(routine_id("callbackselect")),startdir,0}, browse_info)  -- WinHwnd is a tinEWG global variable which provides main window handle 
 
  atom pidl=0 
  sequence ret_dir="" 
 
  -- call the Windows function 
  pidl = callFunc(xSHBrowseForFolderA, {BrowseInfo}) 
  if pidl then 
    if callFunc(xSHGetPathFromIDListA, {pidl,szDispName}) then 
      ret_dir=peek_string(szDispName) 
    else 
      ret_dir="" 
    end if 
  end if 
 
  free (sztitle) 
  free (BrowseInfo) 
  free (szDispName) 
  free (startdir) 
  return ret_dir 
end function 

I should have used getParams() to retrieve the function results but I feel tired and I am not able to do the job now.

Unfortunately, this example does not work correctly with 64-bit architecture. It uses callbacks and I didn't find where it goes wrong.

Jean-Marc