.loop:
    cmp      rax,5
    jbe      .exit_loop
    mov      rdx,rax
    shr      rdx,2
    and      rax,3
    add      rax,rdx
    jmp      .loop
.exit_loop:

    cmp      rax,3
    cmc
    sbb      rdx,rdx
    and      rdx,3
    sub      rax,rdx