ASM Community

Hello everybody, I am still learning assembly, I wish to write an assembly dll for use with vb.  I am stuck on how to pass an array of string from vb.  My code is as follows:

asmStringByRef proc lpString:DWORD,lpRetByRef:PTR DWORD
   
;;; copy byte by byte from lpString to array b, worked ok
;local b[15]:byte
;mov esi,lpString
;lea eax,b
;mov edi,eax
;@label:
;mov al,
;inc esi
;mov , al
;inc edi
;cmp al,0
;jne @label

;invoke MessageBox,NULL,lpString,addr AppName,MB_OK ; need to fix ths line when lpString is LPSTR

;;; Following works byte by byte, even if param 2 is dword/LPSTR
;;; Fails if param 1 is of type LPSTR
mov esi, dword ptr ; also works if dword ptr [] removed
mov edi, dword ptr
@label:
mov al,
inc esi
mov byte ptr ,al
inc edi
cmp al,0
jne @label

Ret
asmStringByRef EndP

This proc doesnt work if I pass something like this in vb:

Private Declare Sub asmStringByRef Lib "C:\asmICLogix.dll" (ByVal sByVal As String, sByRef As String)

Private Sub Form_Load()
Dim s(0 To 6) As String
Dim y As String
Dim i As Long
    For i = 0 To 6
        s(i) = "abcdef" & i '& String(249, vbNullChar)
    Next i
   
    For i = 0 To 1 ' not supported
      asmStringByRef s(0), y ' this works
      MsgBox "y: " & y
    Next i
   
End Sub

Please help me. Thanks a lot.