AGC implementation in Simulink

Hello everybody,

I want to implement an AGC in my Simulink project, which is able to adjust the gain in 6 dB steps. This block should be able to have a maximum gain of 36 dB. With the normal AGC block in Simulink, there is no possibility to adjust the step size so that the gain steps are 6 dB high. Does anyone know how to implement such kind of AGC ?