It's perhaps worth separating the tasks. Also there is the question of whether you want the multiplexer to change if the S inputs change?. As shown they are read once at the start, when normally they ...
What i am trying to do is to develop a multiplexer, i have 4 inputs and 2 modifiers with 4 combinations: 0&0,1&0,0&1,1&1. So with every combination there is one output, with the 4 inp ...