web/content/notes/drafts/assembly.md

tags, author, draft, showToc, title

tags	author	draft	showToc	title
computer-science notes	TrudeEH	true	true	Assembly

#todo

Assembler/Compiler

• gcc GNU C Compiler (The package includes as (assembler) and ld (linker))

as <file.asm> -o <output.o> # Assemble
gcc -o <output_file> <output.o> -nostdlib -static # Link using gcc
ld <output.o> # Link using ld

Hello World

.global _start
.intel_syntax noprefix
_start:
	// sys_write (Print to stdout)
	mov rax, 1
	mov rdi, 1
	lea rsi, [hello_world]
	// Buffer length
	mov rdx, 14
	syscall
	// sys_exit (safely end the program with a re turn code)
	mov rax, 60
	// Exit with code 0
	mov rdi, 0
	syscall
	
hello_world:
	// ASCII, zero delimited
	.asciz "Hello, World!\n"

To know which system calls we can execute and which values needed for the registers, refer to this table.