bool32 b1
bool32 b2
bool32 b3
bool32 b4
int32.positive output
bool32 active
int index;
index = 0;
if (inlet_b1)
index = 0;
else if (inlet_b2)
index = 1;
else if (inlet_b3)
index = 2;
else if (inlet_b4)
index = 3;
outlet_out = index;
outlet_active = (inlet_b1) || (inlet_b2) || (inlet_b3) || (inlet_b4);