Call & Return

Functions with CALL and RET

Functions in assembly are created with call and ret:

call my_function   ; push return address, jump to my_function
; ... execution continues here after ret ...

my_function:
	; function body
	ret                ; pop return address, jump back to caller

How It Works

1. call label pushes the address of the next instruction onto the stack, then jumps to label
2. ret pops the return address from the stack and jumps to it

A Simple Function

; Function that prints a character stored in rbx
print_char:
	push rbx
	mov rax, 1
	mov rdi, 1
	mov rsi, rsp
	mov rdx, 1
	syscall
	add rsp, 8
	ret

Your Task

Write a print_newline function and a print_digit function:

• print_digit: takes a digit (0-9) in rbx, converts to ASCII, and prints it
• print_newline: prints a newline character

Use these functions to print "3\n7\n"