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flat assembler > Windows > Shortest (size of code) macro for SINGLE INSTANCE

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Joined: 24 Mar 2012
Posts: 168
Location: Russian Federation, Sochi
macro singleinstance _class*,_title*,exitjmp*,noextra {;(maybe ":0" instead "*" more wise for class & title)
        invoke  FindWindow,_class,_title
        or      eax,eax
  match any,noextra \{ jnz     exitjmp \}
  match ,noextra \{
  \local .init
        jz      .init
        push    SW_RESTORE
        push    eax
        call    [IsIconic]
        sub     esp,4
        or      eax,eax
        jz      @F
        call    [ShowWindow]
        jmp     exitjmp ;"jmp exitjmp" is more preferrable than "sub     esp,8", however any of them are valid here
        call    [SetForegroundWindow] 
        jmp     exitjmp 
  .init: \}

use case:
; Template for program using standard Win32 headers

format PE GUI 4.0
entry main.start

include 'win32w.inc'

section '.text' code readable executable
        invoke  GetModuleHandle,0
        mov     [hInstance],eax

        singleinstance _class,_title,.exit;,noactivating

        invoke  LoadCursor,0,IDC_ARROW ; Try to remove theese 2 lines
        mov     [wc.hCursor],eax ; and move cursor slowly from outer to the window, and you understand why they should never be skipped.

        invoke  RegisterClass,wc
        test    eax,eax
        jz      .error

        invoke  CreateWindowEx,0,_class,_title,WS_VISIBLE+WS_DLGFRAME+WS_SYSMENU+WS_MINIMIZEBOX,128,128,256,192,NULL,NULL,[hInstance],NULL
        test    eax,eax
        jz      .error

        invoke  GetMessage,msg,NULL,0,0
        cmp     eax,1
        jb      .exit
        jne     .msg_loop
        invoke  TranslateMessage,msg
        invoke  DispatchMessage,msg
        jmp     .msg_loop

        invoke  MessageBox,NULL,_error,NULL,MB_ICONERROR+MB_OK

        invoke  ExitProcess,[msg.wParam]

proc WindowProc uses ebx esi edi, hwnd,wmsg,wparam,lparam
        cmp     [wmsg],WM_DESTROY
        je      .wmdestroy
        invoke  DefWindowProc,[hwnd],[wmsg],[wparam],[lparam]
        jmp     .finish
        invoke  PostQuitMessage,0
        xor     eax,eax

section '.data' data readable writeable
  label hInstance:dword at wc.hInstance ; no needed to create data members twice for same purpose
  _class TCHAR 'FASMWIN32',0
  _title TCHAR 'Win32 program template',0
  _error TCHAR 'Startup failed.',0


  msg MSG

section '.idata' import data readable writeable

  library kernel32,'KERNEL32.DLL',\

  include 'api\kernel32.inc'
  include 'api\user32.inc'    
so, you can forgot about manual realization of single instancing & just use macro fast & readable

I don`t like to refer by "you" to one person.
My soul requires acronim "thou" instead.
Post 10 Feb 2018, 00:54
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When all else fails, read the source

Joined: 24 Aug 2004
Posts: 15912
Location: SDSS J140821.67+025733.2
Using FindWindow is not guaranteed to be atomic or unique. Perhaps instead you can consider using a mutex. Mutexes are specifically designed for this sort of thing, they are guaranteed to give you a single instance.

Moving to Windows forum.
Post 10 Feb 2018, 04:10
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