Programming Fundamentals/Variables/Assembly
name_x86.asm
[edit | edit source];This program displays "Hello <name>!" based on user input.
;
;References:
; https://www.tutorialspoint.com/assembly_programming/
; https://www.tutorialspoint.com/compile_assembly_online.php
; https://www.tutorialspoint.com/assembly_programming/assembly_system_calls.htm
global _start
_start: section .text
prompt_out: mov eax, sys_write ;eax = sys_write
mov ebx, stdout ;ebx = stdout
mov ecx, prompt ;ecx = prompt address
mov edx, prompt_len ;edx = prompt length
int sys_call ;call system
name_in: mov eax, sys_read ;eax = sys_read
mov ebx, stdin ;ebx = stdin
mov ecx, name ;ecx = name address
mov edx, name_maxlen ;edx = name maximum length
int sys_call ;call system
sub eax, 1 ;eax = input name length - newline
mov [name_len], eax ;save name length
hello_out: mov eax, sys_write ;eax = sys_write
mov ebx, stdout ;ebx = stdout
mov ecx, hello ;ecx = prompt address
mov edx, hello_len ;edx = prompt length
int sys_call ;call system
name_out: mov eax, sys_write ;eax = sys_write
mov ebx, stdout ;ebx = stdout
mov ecx, name ;ecx = prompt address
mov edx, [name_len] ;edx = name length
int sys_call ;call system
exclam_out: mov eax, sys_write ;eax = sys_write
mov ebx, stdout ;ebx = stdout
mov ecx, exclam ;ecx = exclamation address
mov edx, exclam_len ;edx = exclamation length
int sys_call ;call system
exit: mov eax, sys_exit ;eax = sys_exit
mov ebx, 0 ;ebx = return code (0)
int sys_call ;call system
section .data
sys_exit equ 1
sys_read equ 3
sys_write equ 4
sys_call equ 0x80
stdin equ 0
stdout equ 1
linefeed equ 0x0a
newline db linefeed
newline_len equ $ - newline
prompt db 'Enter your name:', linefeed
prompt_len equ $ - prompt
name_len dd 4
hello db 'Hello '
hello_len equ $ - hello
exclam db '!'
exclam_len equ $ - exclam
section .bss
name resb 255
name_maxlen equ $ - name
name_x64.asm
[edit | edit source];This program displays 'Hello world!"
;
;References:
; http://cs.lmu.edu/~ray/notes/nasmtutorial/
; http://blog.rchapman.org/posts/Linux_System_Call_Table_for_x86_64/
global _start
_start: section .text
prompt_out: mov rax, sys_write ;rax = sys_write
mov rdi, stdout ;rdi = stdout
mov rsi, prompt ;rsi = prompt address
mov rdx, prompt_len ;rdx = prompt length
syscall ;call system
name_in: mov rax, sys_read ;rax = sys_read
mov rdi, stdin ;rdi = stdin
mov rsi, name ;rsi = name address
mov rdx, name_maxlen ;rdx = name maximum length
syscall ;call system
mov [name_len], rax ;save name length
hello_out: mov rax, sys_write ;rax = sys_write
mov rdi, stdout ;rdi = stdout
mov rsi, hello ;rsi = hello address
mov rdx, hello_len ;rdx = hello length
syscall ;call system
name_out: mov rax, sys_write ;rax = sys_write
mov rdi, stdout ;rdi = stdout
mov rsi, name ;rsi = name address
mov rdx, [name_len] ;rdx = name length
syscall ;call system
exclam_out: mov rax, sys_write ;eax = sys_write
mov rdi, stdout ;rdi = stdout
mov rsi, exclam ;rsi = exclam address
mov rdx, exclam_len ;rdx = name length
syscall ;call system
exit: mov rax, sys_exit ;rax = sys_exit
mov rdi, 0 ;rdi = return code (0)
syscall ;call system
section .data
sys_read equ 0
sys_write equ 1
sys_exit equ 60
stdin equ 0
stdout equ 1
linefeed equ 0x0a
prompt db "Enter your name:", linefeed
prompt_len equ $ - prompt
name_len dq 0
hello db 'Hello '
hello_len equ $ - hello
exclam db '!'
exclam_len equ $ - exclam
section .bss
name resb 255
name_maxlen equ $ - name
Try It
[edit | edit source]Copy and paste the code above into one of the following free online development environments or use your own Assembly compiler / interpreter / IDE.