.intel_syntax noprefix
.section .data

n:  .quad   10      # define the fibonacci number that should be calculated

.section .text

.global _start

_start:
    # call Fibonacci function f(n)
    push    [n]     # parameter: fibonacci number to calculate
    call    f       # call function
    add rsp, 8      # remove parameter from stack

    # print calculated Fibonacci number on stdout
    #call   printnumber

    # exit process with exit code 0
    mov rax, 1
    mov rbx, 0
    int 0x80

# f: Calculates a Fibonacci number
#   f(n) = {n, if n<=1; f(n-1)+f(n-2), else}.
#   Parameter: Integer n >= 0, passed on stack
#   Returns:   Fibonacci number f(n), returned in rax
.type f, @function
f:
    push rbp    # basepointer auf stack pushen
    mov rbp, rsp    # basepointer bekommt Wert des stackpointers
    add rbp, 8  # 1.Parameter
    mov rbx, [rbp]  # rbx= 1.Paramter

    cmp rbx, 0  # wenn n=0 passiert nichts, jmp zu end
    je end

    cmp rbx, 1  # wenn n=1 jmp zu baseone
    je baseone

    dec rbx     # n-1
    push [rbx]  # push n-1
    call f      # call f(n-1)

    dec rbx     # n-2
    push [rbx]  # push n-2
    call f      # call f(n-2)



baseone: add rdi, 1     # rdi = rdi + 1

end:    pop rbp     # basepointer wieder vom Stack entfernen
    ret