section .data
    result db 0            ; переменная для хранения результата
    operand1 db 0          ; первый операнд
    operand2 db 0          ; второй операнд
    operator db 0          ; оператор (+, -, *, /)

section .text
    global _start

_start:
    ; ввод первого операнда
    mov eax, 3              ; sys_read system call
    mov ebx, 0              ; file descriptor 0 (стандартный ввод)
    mov ecx, operand1       ; буфер для ввода
    mov edx, 2              ; количество байт для чтения
    int 0x80                ; вызов системного прерывания

    ; конвертация в число
    mov eax, operand1
    sub eax, '0'
    mov operand1, al

    ; ввод оператора
    mov eax, 3
    mov ebx, 0
    mov ecx, operator
    mov edx, 1
    int 0x80

    ; ввод второго операнда
    mov eax, 3
    mov ebx, 0
    mov ecx, operand2
    mov edx, 2
    int 0x80

    ; конвертация в число
    mov eax, operand2
    sub eax, '0'
    mov operand2, al

    ; выполнение операции
    mov al, operator
    cmp al, '+'             ; сложение
    je add_oper
    cmp al, '-'             ; вычитание
    je sub_oper
    cmp al, '*'             ; умножение
    je mul_oper
    cmp al, '/'             ; деление
    je div_oper

add_oper:
    mov al, operand1
    add al, operand2
    mov result, al
    jmp print_result

sub_oper:
    mov al, operand1
    sub al, operand2
    mov result, al
    jmp print_result

mul_oper:
    mov al, operand1
    imul al, operand2
    mov result, al
    jmp print_result

div_oper:
    mov al, operand1
    mov bl, operand2
    cmp bl, 0
    je division_by_zero
    xor ah, ah
    idiv bl
    mov result, al
    jmp print_result

division_by_zero:
    mov eax, 4              ; sys_write system call
    mov ebx, 1              ; file descriptor 1 (стандартный вывод)
    mov ecx, division_error ; сообщение об ошибке деления на ноль
    mov edx, division_error_len
    int 0x80
    jmp exit_program

print_result:
    ; вывод результата
    mov eax, 4              ; sys_write system call
    mov ebx, 1              ; file descriptor 1 (стандартный вывод)
    mov ecx, result
    mov edx, 1
    add ecx, '0'
    int 0x80

exit_program:
    mov eax, 1              ; sys_exit system call
    xor ebx, ebx            ; код возврата 0
    int 0x80
    ret

section .data
    division_error db 'Error: Division by zero', 0
    division_error_len equ $ - division_error 

Assembly Online Compiler

Write, Run & Share Assembly code online using OneCompiler's Assembly online compiler for free. It's one of the robust, feature-rich online compilers for Assembly language. Getting started with the OneCompiler's Assembly compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as Assembly and start coding.

About Assembly

Assembly language(asm) is a low-level programming language, where the language instructions will be more similar to machine code instructions.

Every assembler may have it's own assembly language designed for a specific computers or an operating system.

Assembly language requires less execution time and memory. It is more helful for direct hardware manipulation, real-time critical applications. It is used in device drivers, low-level embedded systems etc.

Syntax help

Assembly language usually consists of three sections,

  1. Data section

    To initialize variables and constants, buffer size these values doesn't change at runtime.

  2. bss section

    To declare variables

  3. text section

    _start specifies the starting of this section where the actually code is written.

Variables

There are various define directives to allocate space for variables for both initialized and uninitialized data.

1. To allocate storage space to Initialized data

Syntax

variable-name    define-directive    initial-value 
Define DirectiveDescriptionAllocated Space
DBDefine Byte1 byte
DWDefine Word2 bytes
DDDefine Doubleword4 bytes
DQDefine Quadword8 bytes
DTDefine Ten Bytes10 bytes

2. To allocate storage space to un-initialized data

Define DirectiveDescription
RESBReserve a Byte
RESWReserve a Word
RESDReserve a Doubleword
RESQReserve a Quadword
RESTReserve a Ten Bytes

Constants

Constants can be defined using

1. equ

  • To define numeric constants
CONSTANT_NAME EQU regular-exp or value

2. %assign

  • To define numeric constants.
%assign constant_name value

3. %define

  • To define numeric or string constants.
%define constant_name value

Loops

Loops are used to iterate a set of statements for a specific number of times.

mov ECX,n
L1:
;<loop body>
loop L1

where n specifies the no of times loops should iterate.

Procedures

Procedure is a sub-routine which contains set of statements. Usually procedures are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

procedure_name:
   ;procedure body
   ret