 section .text
    global _start       ;must be declared for using gcc
_start:                     ;tell linker entry point

    ; Print "Enter first dig: "
    mov eax, 4           ; syscall number for sys_write
    mov ebx, 1           ; file descriptor (stdout)
    mov ecx, msg1        ; pointer to the message
    mov edx, len1        ; length of the message
    int 0x80             ; interrupt to invoke syscall

    ; Read the first digit
    mov eax, 3           ; syscall number for sys_read
    mov ebx, 0           ; file descriptor (stdin)
    mov ecx, digit1      ; buffer to store the first digit
    mov edx, 1           ; number of bytes to read
    int 0x80             ; interrupt to invoke syscall

    ; Print "Enter second dig: "
    mov eax, 4           ; syscall number for sys_write
    mov ebx, 1           ; file descriptor (stdout)
    mov ecx, msg2        ; pointer to the message
    mov edx, len2        ; length of the message
    int 0x80             ; interrupt to invoke syscall

    ; Read the second digit
    mov eax, 3           ; syscall number for sys_read
    mov ebx, 0           ; file descriptor (stdin)
    mov ecx, digit2      ; buffer to store the second digit
    mov edx, 1           ; number of bytes to read
    int 0x80             ; interrupt to invoke syscall

    ; Compare the digits
    cmp byte [digit1], byte [digit2]
    je  end1             ; Jump to end1 if digits are equal

    ; Print "The digits are not the same "
    mov eax, 4           ; syscall number for sys_write
    mov ebx, 1           ; file descriptor (stdout)
    mov ecx, msg4        ; pointer to the message
    mov edx, len4        ; length of the message
    int 0x80             ; interrupt to invoke syscall

    ; Exit the program
    mov eax, 1           ; syscall number for sys_exit
    xor ebx, ebx         ; exit code 0
    int 0x80             ; interrupt to invoke syscall

end1:
    ; Print "The digits are the same : "
    mov eax, 4           ; syscall number for sys_write
    mov ebx, 1           ; file descriptor (stdout)
    mov ecx, msg3        ; pointer to the message
    mov edx, len3        ; length of the message
    int 0x80             ; interrupt to invoke syscall

    ; Exit the program
    mov eax, 1           ; syscall number for sys_exit
    xor ebx, ebx         ; exit code 0
    int 0x80             ; interrupt to invoke syscall

section .data

msg1 db 'Enter first dig: ', 0xa ; our dear string
len1 equ $ - msg1                 ; length of our dear string
msg2 db 'Enter second dig : ', 0xa ; our dear string
len2 equ $ - msg2                  ; length of our dear string
msg3 db 'The digits are the same : ', 0xa ; our dear string
len3 equ $ - msg3                           ; length of our dear string
msg4 db 'The digits are not the same ', 0xa ; our dear string
len4 equ $ - msg4                           ; length of our dear string

digit1 resb 1   ; reserve 1 byte for the first digit
digit2 resb 1   ; reserve 1 byte for the second digit

created 1 year ago

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,

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.

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 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

2. To allocate storage space to un-initialized data

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

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