exemplos assemblys

comparador.asm

default rel

section .data
    valorA      dd 42
    valorB      dd 17

    msg_maior   db "valorA e maior que valorB", 10
    len_maior   equ $ - msg_maior

    msg_menor   db "valorA e menor ou igual a valorB", 10
    len_menor   equ $ - msg_menor

section .bss
    written resd 1

section .text
    global _start
    extern GetStdHandle
    extern WriteFile
    extern ExitProcess

_start:
    sub rsp, 40

    ; pegar stdout handle
    mov ecx, -11                 ; STD_OUTPUT_HANDLE
    call GetStdHandle
    mov rbx, rax                ; salvar handle

    mov eax, [valorA]
    mov edx, [valorB]
    cmp eax, edx
    jle menor

maior:
    mov rcx, rbx                ; handle
    lea rdx, [msg_maior]        ; buffer
    mov r8d, len_maior          ; tamanho
    lea r9, [written]           ; bytes escritos
    mov qword [rsp+32], 0       ; lpOverlapped = NULL
    call WriteFile
    jmp fim

menor:
    mov rcx, rbx
    lea rdx, [msg_menor]
    mov r8d, len_menor
    lea r9, [written]
    mov qword [rsp+32], 0
    call WriteFile

fim:
    xor ecx, ecx
    call ExitProcess

loop.asm

; montar: nasm -f win64 loop.asm -o loop.obj
; linkar: ld loop.obj -o loop.exe -lkernel32 -e _start

extern GetStdHandle
extern WriteConsoleA
extern ExitProcess

section .bss
    char    resb 1
    written resd 1

section .text
    global _start

_start:
    ; HANDLE = GetStdHandle(-11)
    mov rcx, -11
    call GetStdHandle
    mov rbx, rax

    xor rsi, rsi      ; contador = 0

loop:
    cmp rsi, 11       ; até 10
    jge fim

    ; ---- conversão número → ASCII ----
    mov rax, rsi
    add al, '0'       ; transforma em caractere
    mov [char], al

    ; WriteConsoleA(handle, &char, 1, &written, NULL)
    mov rcx, rbx
    lea rdx, [char]
    mov r8, 1
    lea r9, [written]

    sub rsp, 40
    mov qword [rsp+32], 0
    call WriteConsoleA
    add rsp, 40

    ; imprimir espaço (opcional)
    mov byte [char], ' '

    mov rcx, rbx
    lea rdx, [char]
    mov r8, 1
    lea r9, [written]

    sub rsp, 40
    mov qword [rsp+32], 0
    call WriteConsoleA
    add rsp, 40

    inc rsi
    jmp loop

fim:
    mov rcx, 0
    call ExitProcess

tabuada.asm

default rel

section .data
    numero      dd 7

    prefixo     db " x ", 0
    igual       db " = ", 0
    newline     db 10, 0

section .bss
    buffer      resb 32
    written     resd 1

section .text
    global _start
    extern GetStdHandle
    extern WriteFile
    extern ExitProcess

;---------------------------------------
; imprime string (rcx=handle, rdx=ptr, r8=tamanho)
print:
    mov r9, written
    mov qword [rsp+32], 0
    call WriteFile
    ret

;---------------------------------------
; converte inteiro em string (eax → buffer)
; retorna: rdx=ponteiro, r8=tamanho
itoa:
    lea rsi, [buffer+31]
    mov byte [rsi], 0
    mov ecx, 10

.convert:
    dec rsi
    xor edx, edx
    div ecx
    add dl, '0'
    mov [rsi], dl
    test eax, eax
    jnz .convert

    mov rdx, rsi
    lea r8, [buffer+31]
    sub r8, rsi
    ret

;---------------------------------------
_start:
    sub rsp, 40

    ; stdout handle
    mov ecx, -11
    call GetStdHandle
    mov rbx, rax

    mov r12d, 0
    mov r13d, [numero]

.loop:
    cmp r12d, 10
    jg .fim

    ; imprime numero
    mov eax, r13d
    call itoa
    mov rcx, rbx
    call print

    ; " x "
    mov rcx, rbx
    lea rdx, [prefixo]
    mov r8d, 3
    call print

    ; imprime contador
    mov eax, r12d
    call itoa
    mov rcx, rbx
    call print

    ; " = "
    mov rcx, rbx
    lea rdx, [igual]
    mov r8d, 3
    call print

    ; resultado
    mov eax, r13d
    imul eax, r12d
    call itoa
    mov rcx, rbx
    call print

    ; newline
    mov rcx, rbx
    lea rdx, [newline]
    mov r8d, 1
    call print

    inc r12d
    jmp .loop

.fim:
    xor ecx, ecx
    call ExitProcess