Assembly language examples using NASM on Windows
Basic Window - 32 bit
Description
Creates a basic window, 32 bit. This could be used as the starting point for a larger GUI application.Assemble
- nasm -f win32 BasicWindow32.asm -o BasicWindow32.obj
Link
- golink /entry:Start kernel32.dll user32.dll BasicWindow32.obj
- polink /ENTRY:Start /SUBSYSTEM:WINDOWS /LIBPATH:c:\lib32 kernel32.lib user32.lib BasicWindow32.obj
Notes
Double click the icon to run the executable.The window can only be moved, resized and closed.
The window is not centred on the screen.
The window is the correct width and height, but we actually wanted the client area that size instead. This is due to the window frame
and menu bar not being taken in to consideration.
Code
; Basic Window, 32 bit. V1.01
COLOR_WINDOW EQU 5 ; Constants
CS_BYTEALIGNWINDOW EQU 2000h
CS_HREDRAW EQU 2
CS_VREDRAW EQU 1
CW_USEDEFAULT EQU 80000000h
IDC_ARROW EQU 7F00h
IDI_APPLICATION EQU 7F00h
IMAGE_CURSOR EQU 2
IMAGE_ICON EQU 1
LR_SHARED EQU 8000h
NULL EQU 0
SW_SHOWNORMAL EQU 1
WM_DESTROY EQU 2
WS_EX_COMPOSITED EQU 2000000h
WS_OVERLAPPEDWINDOW EQU 0CF0000h
WindowWidth EQU 640
WindowHeight EQU 480
extern _CreateWindowExA@48 ; Import external symbols
extern _DefWindowProcA@16 ; Windows API functions, decorated
extern _DispatchMessageA@4
extern _ExitProcess@4
extern _GetMessageA@16
extern _GetModuleHandleA@4
extern _IsDialogMessageA@8
extern _LoadImageA@24
extern _PostQuitMessage@4
extern _RegisterClassExA@4
extern _ShowWindow@8
extern _TranslateMessage@4
extern _UpdateWindow@4
global Start ; Export symbols. The entry point
section .data ; Initialized data segment
WindowName db "Basic Window 32", 0
ClassName db "Window", 0
section .bss ; Uninitialized data segment
hInstance resd 1
section .text ; Code segment
Start:
push NULL
call _GetModuleHandleA@4
mov dword [hInstance], EAX
call WinMain
.Exit:
push NULL
call _ExitProcess@4
WinMain:
push EBP ; Set up a stack frame
mov EBP, ESP
sub ESP, 80 ; Space for 80 bytes of local variables
%define wc EBP - 80 ; WNDCLASSEX structure. 48 bytes
%define wc.cbSize EBP - 80
%define wc.style EBP - 76
%define wc.lpfnWndProc EBP - 72
%define wc.cbClsExtra EBP - 68
%define wc.cbWndExtra EBP - 64
%define wc.hInstance EBP - 60
%define wc.hIcon EBP - 56
%define wc.hCursor EBP - 52
%define wc.hbrBackground EBP - 48
%define wc.lpszMenuName EBP - 44
%define wc.lpszClassName EBP - 40
%define wc.hIconSm EBP - 36
%define msg EBP - 32 ; MSG structure. 28 bytes
%define msg.hwnd EBP - 32 ; Breaking out each member is not necessary
%define msg.message EBP - 28 ; in this case, but it shows where each
%define msg.wParam EBP - 24 ; member is on the stack
%define msg.lParam EBP - 20
%define msg.time EBP - 16
%define msg.pt.x EBP - 12
%define msg.pt.y EBP - 8
%define hWnd EBP - 4
mov dword [wc.cbSize], 48 ; [EBP - 80]
mov dword [wc.style], CS_HREDRAW | CS_VREDRAW | CS_BYTEALIGNWINDOW ; [EBP - 76]
mov dword [wc.lpfnWndProc], WndProc ; [EBP - 72]
mov dword [wc.cbClsExtra], NULL ; [EBP - 68]
mov dword [wc.cbWndExtra], NULL ; [EBP - 64]
mov EAX, dword [hInstance] ; Global
mov dword [wc.hInstance], EAX ; [EBP - 60]
push LR_SHARED
push NULL
push NULL
push IMAGE_ICON
push IDI_APPLICATION
push NULL
call _LoadImageA@24 ; Large program icon
mov dword [wc.hIcon], EAX ; [EBP - 56]
push LR_SHARED
push NULL
push NULL
push IMAGE_CURSOR
push IDC_ARROW
push NULL
call _LoadImageA@24 ; Cursor
mov dword [wc.hCursor], EAX ; [EBP - 52]
mov dword [wc.hbrBackground], COLOR_WINDOW + 1 ; [EBP - 48]
mov dword [wc.lpszMenuName], NULL ; [EBP - 44]
mov dword [wc.lpszClassName], ClassName ; [EBP - 40]
push LR_SHARED
push NULL
push NULL
push IMAGE_ICON
push IDI_APPLICATION
push NULL
call _LoadImageA@24 ; Small program icon
mov dword [wc.hIconSm], EAX ; [EBP - 36]
lea EAX, [wc] ; [EBP - 80]
push EAX
call _RegisterClassExA@4
push NULL
push dword [hInstance] ; Global
push NULL
push NULL
push WindowHeight
push WindowWidth
push CW_USEDEFAULT
push CW_USEDEFAULT
push WS_OVERLAPPEDWINDOW
push WindowName ; Global
push ClassName ; Global
push WS_EX_COMPOSITED
call _CreateWindowExA@48
mov dword [hWnd], EAX ; [EBP - 4]
push SW_SHOWNORMAL
push dword [hWnd] ; [EBP - 4]
call _ShowWindow@8
push dword [hWnd] ; [EBP - 4]
call _UpdateWindow@4
.MessageLoop:
lea EAX, [msg] ; [EBP - 32]
push NULL
push NULL
push NULL
push EAX
call _GetMessageA@16
cmp EAX, 0
je .Done
lea EAX, [msg] ; [EBP - 32]
push EAX
push dword [hWnd] ; [EBP - 4]
call _IsDialogMessageA@8 ; For keyboard strokes
cmp EAX, 0
jne .MessageLoop ; Skip TranslateMessage and DispatchMessage
lea EAX, [msg] ; [EBP - 32]
push EAX
call _TranslateMessage@4
lea EAX, [msg] ; [EBP - 32]
push EAX
call _DispatchMessageA@4
jmp .MessageLoop
.Done:
mov ESP, EBP ; Remove the stack frame
pop EBP
xor EAX, EAX
ret
WndProc:
push EBP ; Set up a Stack frame
mov EBP, ESP
%define hWnd EBP + 8 ; Location of the 4 passed parameters from
%define uMsg EBP + 12 ; the calling function
%define wParam EBP + 16 ; We can now access these parameters by name
%define lParam EBP + 20
cmp dword [uMsg], WM_DESTROY ; [EBP + 12]
je WMDESTROY
DefaultMessage:
push dword [lParam] ; [EBP + 20]
push dword [wParam] ; [EBP + 16]
push dword [uMsg] ; [EBP + 12]
push dword [hWnd] ; [EBP + 8]
call _DefWindowProcA@16
mov ESP, EBP ; Remove the stack frame
pop EBP
ret 16 ; Pop 4 parameters off the stack and return
WMDESTROY:
push NULL
call _PostQuitMessage@4
xor EAX, EAX ; WM_DESTROY has been processed, return 0
mov ESP, EBP ; Remove the stack frame
pop EBP
ret 16 ; Pop 4 parameters off the stack and return