Assembly language examples using NASM on Windows
Basic Window Extended - 32 bit
Description
Creates a window with simple functionality, 32 bit.It demonstrates the processing of several WM_ messages, and improves upon the basic window example.
Assemble
- nasm -f win32 BasicWindowExtended32.asm -o BasicWindowExtended32.obj
Link
- golink /entry:Start kernel32.dll user32.dll gdi32.dll BasicWindowExtended32.obj
- polink /ENTRY:Start /SUBSYSTEM:WINDOWS /LIBPATH:c:\lib32 kernel32.lib user32.lib gdi32.lib BasicWindowExtended32.obj
Notes
Double click the icon to run the executable.Improvements over the basic window example
- The window will be centred on the screen
- The client area will now be the correct size (before resizing)
- The window has a background colour
- 2 static controls are created. The text changes colour when clicked
- 2 edit controls are created. The tab key can be used to change focus
- The static and edit controls have their font changed from the system default
- A black rectangle is blitted to the window
- An exit confirmation is displayed when closing the window
Optimisations
When a WM_ message has been processed, Windows usually expects a return value of 0. There now is a single point of return whereEAX is zeroed and the stack frame removed.
WM_CTLCOLOREDIT and WM_CTLCOLORSTATIC need a brush returned instead, in these cases the zeroing of EAX is skipped over.
Code
; Basic Window Extended, 32 bit. V1.04
ANSI_CHARSET EQU 0 ; Constants
BLACKNESS EQU 42h
CLIP_DEFAULT_PRECIS EQU 0
CS_BYTEALIGNWINDOW EQU 2000h
CS_HREDRAW EQU 2
CS_VREDRAW EQU 1
DEFAULT_PITCH EQU 0
ES_AUTOHSCROLL EQU 80h
ES_CENTER EQU 1
FALSE EQU 0
GRAY_BRUSH EQU 2
IDC_ARROW EQU 7F00h
IDI_APPLICATION EQU 7F00h
IDNO EQU 7
IMAGE_CURSOR EQU 2
IMAGE_ICON EQU 1
LR_SHARED EQU 8000h
MB_DEFBUTTON2 EQU 100h
MB_YESNO EQU 4
NULL EQU 0
NULL_BRUSH EQU 5
OPAQUE EQU 2
PROOF_QUALITY EQU 2
SM_CXFULLSCREEN EQU 10h
SM_CYFULLSCREEN EQU 11h
SS_CENTER EQU 1
SS_NOTIFY EQU 100h
SW_SHOWNORMAL EQU 1
TRUE EQU 1
WM_CLOSE EQU 10h
WM_COMMAND EQU 111h
WM_CREATE EQU 1
WM_CTLCOLOREDIT EQU 133h
WM_CTLCOLORSTATIC EQU 138h
WM_DESTROY EQU 2
WM_PAINT EQU 0Fh
WM_SETFONT EQU 30h
OUT_DEFAULT_PRECIS EQU 0
WS_CHILD EQU 40000000h
WS_EX_COMPOSITED EQU 2000000h
WS_OVERLAPPEDWINDOW EQU 0CF0000h
WS_TABSTOP EQU 10000h
WS_VISIBLE EQU 10000000h
WindowWidth EQU 640
WindowHeight EQU 170
Static1ID EQU 100
Static2ID EQU 101
Edit1ID EQU 102
Edit2ID EQU 103
extern _AdjustWindowRectEx@16 ; Import external symbols
extern _BeginPaint@8 ; Windows API functions, decorated
extern _BitBlt@36
extern _CreateFontA@56
extern _CreateSolidBrush@4
extern _CreateWindowExA@48
extern _DefWindowProcA@16
extern _DeleteObject@4
extern _DestroyWindow@4
extern _DispatchMessageA@4
extern _EndPaint@8
extern _ExitProcess@4
extern _GetDlgCtrlID@4
extern _GetMessageA@16
extern _GetModuleHandleA@4
extern _GetStockObject@4
extern _GetSystemMetrics@4
extern _InvalidateRect@12
extern _IsDialogMessageA@8
extern _LoadImageA@24
extern _MessageBoxA@16
extern _PostQuitMessage@4
extern _RegisterClassExA@4
extern _SendMessageA@16
extern _SetBkColor@8
extern _SetBkMode@8
extern _SetTextColor@8
extern _ShowWindow@8
extern _TranslateMessage@4
extern _UpdateWindow@4
global Start ; Export symbols. The entry point
section .data ; Initialized data segment
Static1Colour dd 0F0F0F0h ; Colour (0BBGGRRh)
Static1ColourA dd 020A0F0h
Static2Colour dd 000FFFFh
Static2ColourA dd 08000FFh
Edit1TextColour dd 0F590F5h
Edit1BackColour dd 0A00000h
Edit2TextColour dd 0A56E3Bh
Edit2BackColour dd 0FEFE8Eh
BackgroundColour dd 0A56E3Bh
WindowName db "Basic Window Extended 32", 0
ClassName db "Window", 0
SegoeUI db "Segoe UI", 0
StaticClass db "STATIC", 0
EditClass db "EDIT", 0
Text1 db "ABCDEFGHIJKLMNOPQRSTUVWXYZ_0123456789", 0
Text2 db "abcdefghijklmnopqrstuvwxyz_0123456789", 0
ExitText db "Do you want to exit?", 0
section .bss ; Uninitialized data segment
hInstance resd 1
BackgroundBrush resd 1
Font resd 1
Static1 resd 1
Static2 resd 1
Edit1 resd 1
Edit2 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, 104 ; 104 bytes for local variables
%define Screen.Width EBP - 104
%define Screen.Height EBP - 100
%define ClientArea EBP - 96 ; RECT structure. 16 bytes
%define ClientArea.left EBP - 96
%define ClientArea.top EBP - 92
%define ClientArea.right EBP - 88
%define ClientArea.bottom EBP - 84
%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
push dword [BackgroundColour]
call _CreateSolidBrush@4 ; Create a brush for the window backgound
mov dword [BackgroundBrush], EAX
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]
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 EAX, dword [BackgroundBrush]
mov dword [wc.hbrBackground], EAX ; [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 SM_CXFULLSCREEN
call _GetSystemMetrics@4 ; Get the current screen width
mov dword [Screen.Width], EAX ; [EBP - 104]
push SM_CYFULLSCREEN
call _GetSystemMetrics@4 ; Get the current screen height
mov dword [Screen.Height], EAX ; [EBP - 100]
mov dword [ClientArea.left], 0 ; [EBP - 96]
mov dword [ClientArea.top], 0 ; [EBP - 92]
mov dword [ClientArea.right], WindowWidth ; [EBP - 88]
mov dword [ClientArea.bottom], WindowHeight ; [EBP - 84]
push WS_EX_COMPOSITED ; Extended style
push NULL
push WS_OVERLAPPEDWINDOW ; Style
lea EAX, [ClientArea] ; [EBP - 96]
push EAX
call _AdjustWindowRectEx@16 ; Get window size for the desired client size
; Size is returned in ClientArea
mov EAX, dword [ClientArea.top] ; [EBP - 92]
sub dword [ClientArea.bottom], EAX ; New Height = ClientArea.bottom - ClientArea.top
mov EAX, dword [ClientArea.left] ; [EBP - 96]
sub dword [ClientArea.right], EAX ; New Width = ClientArea.right - ClientArea.left
push NULL
push dword [hInstance]
push NULL
push NULL
push dword [ClientArea.bottom] ; Height. [EBP - 84]
push dword [ClientArea.right] ; Width. [EBP - 88]
xor ECX, ECX
mov EAX, dword [Screen.Height] ; [EBP - 100]
sub EAX, dword [ClientArea.bottom] ; Corrected window height. [EBP - 84]
cmovs EAX, ECX ; Clamp to 0 (top) if negative
shr EAX, 1 ; EAX = (Screen.Height - window height) / 2
push EAX ; Y position, now centred
mov EAX, dword [Screen.Width] ; [EBP - 104]
sub EAX, dword [ClientArea.right] ; Corrected window width. [EBP - 88]
cmovs EAX, ECX ; Clamp to 0 (left) if negative
shr EAX, 1 ; EAX = (Screen.Width - window width) / 2
push EAX ; X position, now centred
push WS_OVERLAPPEDWINDOW
push WindowName
push ClassName
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:
push NULL
push NULL
push NULL
lea EAX, [msg] ; [EBP - 32]
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:
xor EAX, EAX
mov ESP, EBP ; Remove the stack frame
pop EBP
ret
WndProc:
push EBP ; Set up a stack frame
mov EBP, ESP
sub ESP, 68 ; 68 bytes for local variables
%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
%define ps EBP - 68 ; PAINTSTRUCT structure. 64 bytes
%define ps.hdc EBP - 68
%define ps.fErase EBP - 64
%define ps.rcPaint.left EBP - 60
%define ps.rcPaint.top EBP - 56
%define ps.rcPaint.right EBP - 52
%define ps.rcPaint.bottom EBP - 48
%define ps.Restore EBP - 44
%define ps.fIncUpdate EBP - 40
%define ps.rgbReserved EBP - 36
%define hdc EBP - 4
cmp dword [uMsg], WM_CLOSE ; [EBP + 12]
je WMCLOSE
cmp dword [uMsg], WM_COMMAND ; [EBP + 12]
je WMCOMMAND
cmp dword [uMsg], WM_CREATE ; [EBP + 12]
je WMCREATE
cmp dword [uMsg], WM_CTLCOLOREDIT ; [EBP + 12]
je WMCTLCOLOREDIT
cmp dword [uMsg], WM_CTLCOLORSTATIC ; [EBP + 12]
je WMCTLCOLORSTATIC
cmp dword [uMsg], WM_DESTROY ; [EBP + 12]
je WMDESTROY
cmp dword [uMsg], WM_PAINT ; [EBP + 12]
je WMPAINT
DefaultMessage:
push dword [lParam] ; [EBP + 20]
push dword [wParam] ; [EBP + 16]
push dword [uMsg] ; [EBP + 12]
push dword [hWnd] ; [EBP + 8]
call _DefWindowProcA@16
jmp Return
WMCLOSE:
push MB_YESNO | MB_DEFBUTTON2
push WindowName
push ExitText
push dword [hWnd] ; [EBP + 8]
call _MessageBoxA@16
cmp EAX, IDNO
je Return.WM_Processed
push dword [hWnd] ; [EBP + 8]
call _DestroyWindow@4 ; Send a WM_DESTROY message
jmp Return.WM_Processed
WMCOMMAND:
mov EAX, dword [wParam] ; EAX = ID. [EBP + 16]
cmp AX, Static1ID
je .Static1
cmp AX, Static2ID
je .Static2
jmp Return.WM_Processed
.Static1:
mov EAX, dword [Static1Colour]
mov EBX, dword [Static1ColourA]
mov dword [Static1Colour], EBX
mov dword [Static1ColourA], EAX ; Swap colours
push TRUE
push NULL
push dword [lParam] ; Static1 handle. [EBP + 20]
call _InvalidateRect@12 ; Redraw control
jmp Return.WM_Processed
.Static2:
mov EAX, dword [Static2Colour]
mov EBX, dword [Static2ColourA]
mov dword [Static2Colour], EBX
mov dword [Static2ColourA], EAX ; Swap colours
push TRUE
push NULL
push dword [lParam] ; Static2 handle. [EBP + 20]
call _InvalidateRect@12 ; Redraw control
jmp Return.WM_Processed
WMCREATE:
push NULL
push dword [hInstance]
push Static1ID
push dword [hWnd] ; [EBP + 8]
push 20 ; Height
push 400 ; Width
push 10 ; Y
push 120 ; X
push WS_CHILD | WS_VISIBLE | SS_NOTIFY | SS_CENTER
push Text1 ; Default text
push StaticClass
push NULL
call _CreateWindowExA@48
mov dword [Static1], EAX
push NULL
push dword [hInstance]
push Static2ID
push dword [hWnd] ; [EBP + 8]
push 20 ; Height
push 400 ; Width
push 40 ; Y
push 120 ; X
push WS_CHILD | WS_VISIBLE | SS_NOTIFY | SS_CENTER
push Text2 ; Default text
push StaticClass
push NULL
call _CreateWindowExA@48
mov dword [Static2], EAX
push NULL
push dword [hInstance]
push Edit1ID
push dword [hWnd] ; [EBP + 8]
push 20 ; Height
push 400 ; Width
push 70 ; Y
push 120 ; X
push WS_CHILD | WS_VISIBLE | ES_CENTER | WS_TABSTOP | ES_AUTOHSCROLL
push Text1 ; Default text
push EditClass
push NULL
call _CreateWindowExA@48
mov dword [Edit1], EAX
push NULL
push dword [hInstance]
push Edit2ID
push dword [hWnd] ; [EBP + 8]
push 20 ; Height
push 400 ; Width
push 100 ; Y
push 120 ; X
push WS_CHILD | WS_VISIBLE | ES_CENTER | WS_TABSTOP | ES_AUTOHSCROLL
push Text2 ; Default text
push EditClass
push NULL
call _CreateWindowExA@48
mov dword [Edit2], EAX
lea EAX, [SegoeUI]
push EAX
push DEFAULT_PITCH
push PROOF_QUALITY
push CLIP_DEFAULT_PRECIS
push OUT_DEFAULT_PRECIS
push ANSI_CHARSET
push NULL
push NULL
push NULL
push 400 ; Weight
push NULL
push NULL
push NULL
push 20 ; Size
call _CreateFontA@56
mov dword [Font], EAX
push FALSE
push dword [Font]
push WM_SETFONT
push dword [Static1]
call _SendMessageA@16 ; Set Static1 font
push FALSE
push dword [Font]
push WM_SETFONT
push dword [Static2]
call _SendMessageA@16 ; Set Static2 font
push FALSE
push dword [Font]
push WM_SETFONT
push dword [Edit1]
call _SendMessageA@16 ; Set Edit1 font
push FALSE
push dword [Font]
push WM_SETFONT
push dword [Edit2]
call _SendMessageA@16 ; Set Edit2 font
jmp Return.WM_Processed
WMCTLCOLOREDIT: ; For colouring edit controls
push dword [lParam] ; [EBP + 20]
call _GetDlgCtrlID@4 ; EAX = ID
cmp EAX, Edit1ID
je .Edit1
cmp EAX, Edit2ID
je .Edit2
.Default:
push NULL_BRUSH
call _GetStockObject@4 ; Return a brush
jmp Return
.Edit1:
push dword [Edit1TextColour]
push dword [wParam] ; [EBP + 16]
call _SetTextColor@8
push OPAQUE
push dword [wParam] ; [EBP + 16]
call _SetBkMode@8
push dword [Edit1BackColour]
push dword [wParam] ; [EBP + 16]
call _SetBkColor@8
push NULL_BRUSH
call _GetStockObject@4 ; Return a brush
jmp Return
.Edit2:
push dword [Edit2TextColour]
push dword [wParam] ; [EBP + 16]
call _SetTextColor@8
push OPAQUE
push dword [wParam] ; [EBP + 16]
call _SetBkMode@8
push dword [Edit2BackColour]
push dword [wParam] ; [EBP + 16]
call _SetBkColor@8
push NULL_BRUSH
call _GetStockObject@4 ; Return a brush
jmp Return
WMCTLCOLORSTATIC: ; For colouring static controls
push dword [lParam] ; [EBP + 20]
call _GetDlgCtrlID@4 ; EAX = ID
cmp EAX, Static1ID
je .Static1
cmp EAX, Static2ID
je .Static2
.Default:
push NULL_BRUSH
call _GetStockObject@4 ; Return a brush
jmp Return
.Static1:
push dword [Static1Colour]
push dword [wParam] ; [EBP + 16]
call _SetTextColor@8
push OPAQUE
push dword [wParam] ; [EBP + 16]
call _SetBkMode@8
push 0604060h
push dword [wParam] ; [EBP + 16]
call _SetBkColor@8
push NULL_BRUSH
call _GetStockObject@4 ; Return a brush
jmp Return
.Static2:
push dword [Static2Colour]
push dword [wParam] ; [EBP + 16]
call _SetTextColor@8
push OPAQUE
push dword [wParam] ; [EBP + 16]
call _SetBkMode@8
push 0005000h
push dword [wParam] ; [EBP + 16]
call _SetBkColor@8
push GRAY_BRUSH
call _GetStockObject@4 ; Return a brush
jmp Return
WMDESTROY:
push dword [BackgroundBrush]
call _DeleteObject@4
push dword [Font]
call _DeleteObject@4
push NULL
call _PostQuitMessage@4
jmp Return.WM_Processed
WMPAINT:
lea EAX, [ps] ; Starting address of PAINTSTRUCT. [EBP - 68]
push EAX
push dword [hWnd] ; [EBP + 8]
call _BeginPaint@8
mov dword [hdc], EAX
push BLACKNESS ; Operation
push 0 ; Source Y
push 0 ; Source X
push dword [hdc] ; Source device context
push 20 ; Height
push 400 ; Width
push 130 ; Destination Y
push 120 ; Destination X
push dword [hdc] ; Destination device context
call _BitBlt@36 ; Blit a black rectangle
lea EAX, [ps] ; [EBP - 68]
push EAX
push dword [hWnd] ; [EBP + 8]
call _EndPaint@8
Return.WM_Processed:
xor EAX, EAX ; WM_ has been processed, return 0
Return:
mov ESP, EBP ; Remove the stack frame
pop EBP
ret 16 ; Pop 4 parameters off the stack and return