CS 456 - Systems Programming Spring 2024

Displaying ./code/asm/write.asm

; Write
; Compile with: nasm -f elf write.asm
; Link with (64 bit systems require elf_i386 option): ld -m elf_i386 write.o -o write
; Run with: ./write
 
%include    'functions.asm'
 
SECTION .data
filename db 'readme.txt', 0h    ; the filename to create
contents db 'Hello world!', 0h  ; the contents to write
 
SECTION .text
global  _start
 
_start:
 
    mov     ecx, 0777o          ; code continues from lesson 22
    mov     ebx, filename
    mov     eax, 8
    int     80h
 
    mov     edx, 12             ; number of bytes to write - one for each letter of our contents string
    mov     ecx, contents       ; move the memory address of our contents string into ecx
    mov     ebx, eax            ; move the file descriptor of the file we created into ebx
    mov     eax, 4              ; invoke SYS_WRITE (kernel opcode 4)
    int     80h                 ; call the kernel
 
    call    quit                ; call our quit function