section .text
global sswitch

sswitch:
        push rbp
        mov rbp, rsp

        dec rdi
loop:
        inc rdi
        mov dl, [rdi]
        cmp dl, 0
        jz end

        cmp dl, 'A'
        jl loop

        cmp dl, 'z'
        jg loop

        cmp dl, 'Z'
        jg vovelcheck
great:
        add dl, 32
        mov [rdi], dl
vovelcheck:
        cmp dl, 'a'
        je vovel

        cmp dl, 'e'
        je vovel

        cmp dl, 'i'
        je vovel

        cmp dl, 'o'
        je vovel

        cmp dl, 'u'
        je vovel

        cmp dl, 'y'
        je vovel

        jmp loop
vovel:
        mov dl, '*'
        mov [rdi], dl

        jmp loop
end:
        mov rsp, rbp
        pop rbp
        ret