B=:hello_world
call :puts
; exit code 0
J=d0
syscall x3c

:hello_world
str Hello, world!
xa
x0

; output null-terminated string in rbx
:puts
	R=B
	call :strlen
	D=A
	I=R
	J=d1
	syscall d1
	return

; calculate length of string in rbx
:strlen
	; keep pointer to start of string
	D=B
	I=B
	:strlen_loop
	C=1I
	?C=0:strlen_loop_end
	I+=d1
	!:strlen_loop
	:strlen_loop_end
	I-=D
	A=I	
	return