.386 
.model flat,stdcall 
option casemap:none 
WinMain proto :DWORD,:DWORD,:DWORD,:DWORD 

include \masm32\include\windows.inc 
include \masm32\include\user32.inc 
include \masm32\include\kernel32.inc 
include \masm32\include\gdi32.inc 
includelib \masm32\lib\user32.lib 
includelib \masm32\lib\kernel32.lib 
includelib \masm32\lib\gdi32.lib 

.data 
ClassName db "SimpleWinClass",0 
AppName  db "Our First Window",0 
char WPARAM 20h               ; the character the program receives from keyboard 

.data? 
hInstance HINSTANCE ? 
CommandLine LPSTR ? 

.code 
start: 
    invoke GetModuleHandle, NULL 
    mov    hInstance,eax 
    invoke GetCommandLine
    mov CommandLine,eax
    invoke WinMain, hInstance,NULL,CommandLine, SW_SHOWDEFAULT 
    invoke ExitProcess,eax 

WinMain proc hInst:HINSTANCE,hPrevInst:HINSTANCE,CmdLine:LPSTR,CmdShow:DWORD 
    LOCAL wc:WNDCLASSEX 
    LOCAL msg:MSG 
    LOCAL hwnd:HWND 
    mov   wc.cbSize,SIZEOF WNDCLASSEX 
    mov   wc.style, CS_HREDRAW or CS_VREDRAW 
    mov   wc.lpfnWndProc, OFFSET WndProc 
    mov   wc.cbClsExtra,NULL 
    mov   wc.cbWndExtra,NULL 
    push  hInst 
    pop   wc.hInstance 
    mov   wc.hbrBackground,COLOR_WINDOW+1 
    mov   wc.lpszMenuName,NULL 
    mov   wc.lpszClassName,OFFSET ClassName 
    invoke LoadIcon,NULL,IDI_APPLICATION 
    mov   wc.hIcon,eax 
    mov   wc.hIconSm,eax 
    invoke LoadCursor,NULL,IDC_ARROW 
    mov   wc.hCursor,eax 
    invoke RegisterClassEx, addr wc 
    invoke CreateWindowEx,NULL,ADDR ClassName,ADDR AppName,\ 
           WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,\ 
           CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,NULL,\ 
           hInst,NULL 
    mov   hwnd,eax 
    invoke ShowWindow, hwnd,SW_SHOWNORMAL 
    invoke UpdateWindow, hwnd 
    .WHILE TRUE 
                invoke GetMessage, ADDR msg,NULL,0,0 
                .BREAK .IF (!eax) 
                invoke TranslateMessage, ADDR msg 
                invoke DispatchMessage, ADDR msg 
        .ENDW 
    mov     eax,msg.wParam 
    ret 
WinMain endp 

WndProc proc hWnd:HWND, uMsg:UINT, wParam:WPARAM, lParam:LPARAM 
    LOCAL hdc:HDC 
    LOCAL ps:PAINTSTRUCT 

    .IF uMsg==WM_DESTROY 
        invoke PostQuitMessage,NULL 
    .ELSEIF uMsg==WM_CHAR 
        push wParam 
        pop  char 
        invoke InvalidateRect, hWnd,NULL,TRUE 
    .ELSEIF uMsg==WM_PAINT 
        invoke BeginPaint,hWnd, ADDR ps 
        mov    hdc,eax 
        invoke TextOut,hdc,0,0,ADDR char,1 
        invoke EndPaint,hWnd, ADDR ps 
    .ELSE 
        invoke DefWindowProc,hWnd,uMsg,wParam,lParam 
        ret 
    .ENDIF 
    xor    eax,eax 
    ret 
WndProc endp 
end start 

char WPARAM 20h              ; the character the program receives from keyboard