section .data
num1 db 7
num2 db 11
msg_first db "First is closer", 10
msg_first_len equ $ - msg_first
msg_second db "Second is closer", 10
msg_second_len equ $ - msg_second
msg_equal db "Equidistant", 10
msg_equal_len equ $ - msg_equal
section .text
global _start
_start:
movzx rax, byte [num1]
movzx rbx, byte [num2]
sub rax, 10
jge no_abs1
neg rax
no_abs1:
sub rbx, 10
jge no_abs2
neg rbx
no_abs2:
cmp rax, rbx
jl first_closer
jg second_closer
jmp equidistant
first_closer:
mov rax, 1
mov rdi, 1
mov rsi, msg_first
mov rdx, msg_first_len
syscall
jmp exit
second_closer:
mov rax, 1
mov rdi, 1
mov rsi, msg_second
mov rdx, msg_second_len
syscall
jmp exit
equidistant:
mov rax, 1
mov rdi, 1
mov rsi, msg_equal
mov rdx, msg_equal_len
syscall
exit:
mov rax, 60
xor rdi, rdi
syscall 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.
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