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
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
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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.
Assembly language usually consists of three sections,
Data section
To initialize variables and constants, buffer size these values doesn't change at runtime.
bss section
To declare variables
text section
_start
specifies the starting of this section where the actually code is written.
There are various define directives to allocate space for variables for both initialized and uninitialized data.
variable-name define-directive initial-value
Define Directive | Description | Allocated Space |
---|---|---|
DB | Define Byte | 1 byte |
DW | Define Word | 2 bytes |
DD | Define Doubleword | 4 bytes |
DQ | Define Quadword | 8 bytes |
DT | Define Ten Bytes | 10 bytes |
Define Directive | Description |
---|---|
RESB | Reserve a Byte |
RESW | Reserve a Word |
RESD | Reserve a Doubleword |
RESQ | Reserve a Quadword |
REST | Reserve a Ten Bytes |
Constants can be defined using
CONSTANT_NAME EQU regular-exp or value
%assign constant_name value
%define constant_name value
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.
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