How to strore previous condition of variable ?

Hi, I want to create function which simulate dead time effect in three phase inverter. Part of my code is shown below:

function [y_1A, y_2A, krok] = dead_time(kA, kA_p, kA_n, kA_np, k_p)
y_1A = logical(kA);
y_2A = logical(kA_n);
krok = k_p;
znacznik = 0;

if (kA_np == true && kA_n == false)
    y_1A = false;
    znacznik = 1;
end
if znacznik == 1
   krok = krok + 1;

    if krok == 5
       znacznik = 0;
       y_1A = true;
       krok = 0;
    end
  end

variables: kA_np - previous condition of kA_n; kA_p - previous condition of kA; znacznik - marker; krok - step;

This function should wait five steps (five iterations) before set y_1A condition to 1, but it works only for one iteration. Variable "krok" is rises to value of 4 and it is not reset. Have you any ideas how should I do that?

Thank you for your help/answers.