An ARRAY of ASCIIZ STR PTR - Is this possible?

[Mike Trader]

I am trying to speed up my code.
My DLL is passed an ASCIIZ STR PTR for the text I want to manipulate. This text is long and gets sent all over the place so I want to use pointers to avoid moving thousands of characters on many lines each time.
so heres what i have (snippet) ...

'¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤'
FUNCTION LibMain(BYVAL hInstance AS LONG, _
BYVAL fwdReason AS LONG, _
BYVAL lpvReserved AS LONG) EXPORT AS LONG
SELECT CASE fwdReason
CASE %DLL_PROCESS_ATTACH ' DLL loads
DIM TStext(20) AS GLOBAL ASCIIZ PTR
CALL MakeWindow ' Create Main Dialog Window
Blah
Blah
Blah
END FUNCTION
'¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
FUNCTION Stepper(BYVAL StopFlag AS DWORD,_
BYVAL CurrentBar AS SINGLE,_
BYVAL FinalBar AS DWORD,_
BYVAL SentNumBars AS SINGLE,_
TextPtr AS ASCIIZ PTR) EXPORT AS SINGLE
BarNum = INT(CurrentBar) ' value = 1 - FinalBar
Blah
Blah
Blah
TStext(BarNum) = TextPtr
NumBars = NumBars + 1
IF FinalBar = 1 THEN
FOR i = 1 TO NumBars
CONTROL SEND hDlg, 101, %LB_ADDSTRING, 0, TStext(i) ' update the listbox
NEXT
END IF
Blah
Blah
Blah

END FUNCTION









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Kind Regards
Mike

[Michael Mattias]

This text is long and gets sent all over the place so I want to use pointers to avoid moving thousands of characters on many lines each time.

When you dedine a procedure thus:

FUNCTION FOO (X AS ASCIIZ * 2048) AS LONG
END FUNCTION

and call it with:

  J = Foo (Z)

All you EVER pass is a pointer. "Thousands of characters" are NEVER relocated or rebuilt for any procedure call (unless you are passing something requiring conversion from Fixed/ASCIIZ to Dynamic strings or vice-versa).

MCM

[Mike Trader]

ok so if I define 20 ASCIIZ strings with
DIM TStext(20) AS GLOBAL ASCIIZ * 1024

and then load it up one at a time with
TStext(NumBar) = @SentString

when I come to send all those strings to the LISTBOX with
FOR i = 1 TO LastBar
CONTROL SEND hDlg, 165, %LB_ADDSTRING, 0, TStext(i)
NEXT

I am only "sending" a pointer or a handle to the string?

I have not xfer all those characters once?



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Kind Regards
Mike

[Mike Burns]

%LB_ADDSTRING will always make a copy of your string and I don't think it would send a pointer anyway.

Bjorge has a super Virtual listbox control in the source section that avoids
the string copying in a listbox. It is fast and easy to extend.

Mike


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[Lance Edmonds]

Sorry, that is not correct.

The SendMessage() API (which is encapsulated by the CONTROL SEND statement) will send a pointer (whose target is the string data) to the control.


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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Steve Hutchesson]

Lance is right here, from win32.hlp, the lParam of LB_ADDSTRING
is the address of a zero terminated string.

LB_ADDSTRING
wParam = 0; // not used; must be zero
lParam = (LPARAM) (LPCTSTR) lpsz; // address of string to add

In PowerBASIC,

SendMessage hList,%LB_ADDSTRING,0,lpszString.

If you can get the handle of the list box in the DLL, why not
directly load it from the SUB/FUNCTION that allocates the zero
terminated strings so you don't have the overhead of passing
them ? I guess it will depend on how your prog is written but
its a lot faster to directly load it into the list box than to
pass it as parameters on the stack.

Regards,

[email protected]

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[Mike Burns]

You are right that it sends a pointer but the API then uses that pointer to make a copy of the string. Try adding string to a listbox and watch the resources drop.
My understanding is Mike wanted to eliminate that copying in the API.


Bjorge's routine eliminates that resource usage.

Mike

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[Semen Matusovski]

I think that more natural way - to use OWNERDRAWN w/o HASSTRINGS style.
Tested under Win2000 only:

  #Compile Exe
  #Dim All
  #Register None
  #Include "WIN32API.INC"

  %ID_LIST1 = 130
  %nEl = 1000
  Global arr() As String

  CallBack Function DlgProc
      Select Case CbMsg
         Case %WM_DRAWITEM
            Local lpdis As DRAWITEMSTRUCT Ptr
            lpdis = CbLparam
            If @lpdis.itemID = -1 Then Exit Function
            If IsFalse(@lpdis.itemState And %ODS_SELECTED) Then
               FillRect @lpdis.hDC, @lpdis.rcItem, GetStockObject(%WHITE_BRUSH)
               SetBkColor @lpdis.hDC, %WHITE
               SetTextColor @lpdis.hDC, %BLACK
            Else
               FillRect @lpdis.hDC, @lpdis.rcItem, GetStockObject(%BLACK_BRUSH)
               SetBkColor @lpdis.hDC, %BLACK
               SetTextColor @lpdis.hDC, %WHITE
            End If
            TextOut @lpdis.hDC, 0, @lpdis.rcItem.ntop, ByVal StrPtr(arr(@lpdis.itemID)), Len(arr(@lpdis.itemID))
            Function = 1: Exit Function
      End Select
   End Function

  Function PbMain
     Local hDlg As Long, i As Long, hList As Long
     Dialog New 0, "Listbox", , , 100, 70, %WS_CAPTION Or %WS_SYSMENU To hDlg
     Control Add ListBox, hDlg, %ID_LIST1, , 5, 5, 90, 65, _
        %WS_CHILD Or %LBS_OWNERDRAWFIXED Or _
        %WS_TABSTOP Or %LBS_DISABLENOSCROLL Or %WS_VSCROLL, %WS_EX_CLIENTEDGE
     Control Handle hDlg, %ID_LIST1 To hList
     ReDim arr(%nEl - 1)
     For i = 0 To %nEl - 1
        arr(i) = "Item" + Str$(i)
        SendMessage hList, %LB_ADDSTRING, i, 0
     Next
     SendMessage hList, %LB_SETCURSEL, 3, 0 ' Item 3
     Dialog Show Modal hDlg, Call DlgProc
  End Function

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E-MAIL: [email protected]