Editing X86 assembly language (section)

==="Hello world!" program for Windows in MASM and NASM style assembly===
{|class=wikitable
|-
!! MASM !! NASM !! Description
|-
|
<syntaxhighlight lang="nasm">
; requires /coff switch on 6.15 and earlier versions
.386
.model small,c
.stack 1000h
</syntaxhighlight>
|
<syntaxhighlight lang="nasm">
; Image base = 0x00400000
%define RVA(x) (x-0x00400000)
</syntaxhighlight>
|Permeable. MASM requires defining the address model and stack size. 
|-
|<syntaxhighlight lang="nasm">
.data
msg     db "Hello world!",0
</syntaxhighlight>
|<syntaxhighlight lang="nasm">
section .data
msg db "Hello world!"
</syntaxhighlight>
| Data section. We use the db (define byte) pseudo-op to define a string.
|-
|<syntaxhighlight lang="nasm">
.code
includelib libcmt.lib
includelib libvcruntime.lib
includelib libucrt.lib
includelib legacy_stdio_definitions.lib

extrn printf:near
extrn exit:near

public main
main proc
        push    offset msg
        call    printf
        push    0
        call    exit
main endp
end
</syntaxhighlight>

|
<syntaxhighlight lang="nasm">
section .text
push dword msg
call dword [printf]
push byte +0
call dword [exit]
ret

section .idata
dd RVA(msvcrt_LookupTable)
dd -1
dd 0
dd RVA(msvcrt_string)
dd RVA(msvcrt_imports)
times 5 dd 0 ; ends the descriptor table

msvcrt_string dd "msvcrt.dll", 0
msvcrt_LookupTable:
dd RVA(msvcrt_printf)
dd RVA(msvcrt_exit)
dd 0

msvcrt_imports:
printf dd RVA(msvcrt_printf)
exit dd RVA(msvcrt_exit)
dd 0

msvcrt_printf:
dw 1
dw "printf", 0

msvcrt_exit:
dw 2
dw "exit", 0
dd 0
</syntaxhighlight>
|The code (.text section) and the import table. In NASM the import table is manually constructed, while in the MASM example directives are used to simplify the process.
|}