.text
        .type funa, @function
        .global funa
#rdi buf
#rsi a
#rdx b

funa:

    MOV %rdi,   %r12    # buffor
    MOV %rsi,   %r11    # a
    MOV %rdx,   %r10    # b

next:

    CMP $0,     (%r10)  # if(b[i]!=0)
    JE  end

    MOV (%r11), %r9     # zapisz znak z a do tmp
    MOV %r9,    (%r12)  # zapisz znak z tmp do buffer

    INC %r11            # a* = (a+1)*
    INC %r12            # buffor* = (buffor+1)*

    MOV (%r10), %r9     # zapisz znak z b do tmp
    MOV %r9,    (%r12)  # zapisz znak z tmp do buffer

    INC %r10            # b* = (b+1)*
    INC %r12            # buffor* = (buffor+1)*

    JMP next

end:
    MOV %rdi,   %rax
    RET