You need to describe what every code line performs. Please solve all parts with best explanation thank you.

Question: a) (70 Pts) Write down the Verilog design code that gets two 4-bit number inputs from BASYS3 slide switches (number a=SW12(LSB)->SW15(MSB), number b=SW8(LSB)->SW11(MSB)) and adds these numbers if SW3 is ON subtracts these numbers if SW2 is ON (a-b) multiplies these numbers if SW1 is ON divides these numbers if SWO is ON (a/b) AND Displays the result on the 4-digit seven segment display. b) (30 Pts) Give the BASYS3.xdc file for this design code