| ; hello.asm a first program for nasm for Linux, Intel, gcc |
| ; |
| ; assemble: nasm -f elf -l hello.lst hello.asm |
| ; link: gcc -o hello hello.o |
| ; run: hello |
| ; output is: Hello World |
| |
| %include "config.asm" |
| |
| SECTION .data ; data section |
| msg: db "Hello World",10 ; the string to print, 10=cr |
| len: equ $-msg ; "$" means "here" |
| ; len is a value, not an address |
| |
| SECTION .text ; code section |
| global main ; make label available to linker |
| main: ; standard gcc entry point |
| |
| mov edx,len ; arg3, length of string to print |
| mov ecx,msg ; arg2, pointer to string |
| mov ebx,1 ; arg1, where to write, screen |
| mov eax,4 ; write sysout command to int 80 hex |
| int 0x80 ; interrupt 80 hex, call kernel |
| |
| mov ebx,HELLO ; exit code, 0=normal |
| mov eax,1 ; exit command to kernel |
| int 0x80 ; interrupt 80 hex, call kernel |