Convert Integers to Strings in Assembly | Beginner Tutorial for x86-64 | itoa() Assembly Programming

Опубликовано: 02 Июнь 2026
на канале: Mxy

2,432

116

Watch the course from the beginning:    • Learn Assembly For Beginners | Introductio...
Next Video in Course:    • How to Read from the Terminal | Assembly B...
Previous Video in Course:    • How to Multiply & Divide in Assembly | Beg...
Follow along with me in the x64Playground: https://x64.halb.it (Select GNU as the Assembler!)

CODE TO COPY for PRINT() & STRLEN()

;##### CODE START

.intel_syntax noprefix
.global _start
.text
_start:

_print:
push rdi
call _strlen
pop rsi
mov rdx, rax
mov rax, 1
mov rdi, 1
syscall
ret

_exit:
int 3 ;# pause before exiting
mov rax, 60
xor rdi, rdi
syscall

_strlen:
push rbp
mov rbp, rsp
xor rcx, rcx
_strlen_loop:
mov al, [rdi]
cmp al, 0x0
je _strlen_end
inc rcx
inc rdi
jmp _strlen_loop
_strlen_end:
mov rax, rcx
mov rsp, rbp
pop rbp
ret

;#### CODE END

Complete program below from today's video:

;### COMPLETE PROGRAM BELOW

.intel_syntax noprefix
.global _start
.text
_start:
mov rdi, 23451
push rdi

lea rsi, [buf + 32]
call _itoa
mov rdi, rax
call _print

pop rdi
lea rsi, [buf + 32]
call _itob
mov rdi, rax
call _print

call _exit

_itoa:
mov rbx, 10
mov rax, rdi
lea rdi, [rsi]
mov byte ptr [rdi], 0
dec rdi
mov byte ptr [rdi], '\n'

_itoa_loop:
xor rdx, rdx ;# mov rdx, 0
dec rdi
div rbx
add rdx, '0' ;# 48
mov [rdi], dl
cmp rax, 0
jne _itoa_loop
mov rax, rdi
ret

_itob:
mov rbx, 2
mov rax, rdi
lea rdi, [rsi]
mov byte ptr [rdi], 0
dec rdi
mov byte ptr [rdi], '\n'

_itob_loop:
xor rdx, rdx ;# mov rdx, 0
dec rdi
div rbx
add rdx, '0' ;# 48
mov [rdi], dl
cmp rax, 0
jne _itob_loop
mov rax, rdi
ret

_print:
push rdi
call _strlen
pop rsi
mov rdx, rax
mov rax, 1
mov rdi, 1
syscall
ret

_exit:
int 3 ;# pause before exiting
mov rax, 60
xor rdi, rdi
syscall

_strlen:
push rbp
mov rbp, rsp
xor rcx, rcx
_strlen_loop:
mov al, [rdi]
cmp al, 0x0
je _strlen_end
inc rcx
inc rdi
jmp _strlen_loop
_strlen_end:
mov rax, rcx
mov rsp, rbp
pop rbp
ret

.data
buf: .skip 1024

;## COMPLETE PROGRAM END

00:00 itoa in Python/C
03:17 Building the System
05:00 Offsetting Buffers
15:57 Testing
16:15 Challenge #1 - Outputting Binary
21:15 Challenge #2 - Simplifying Args
21:48 Using the Stack