$6.$

Write a VHDL code to implement the $4-$bit ALU using CASE statement. A and B are two $4-$bit inputs to the ALU, and Y is the output. The opcode formed by S$1$ and S$0$ controls the ALU functions as shown in Table.

s$1$

s$0$

Operation Name

Operation

$0$

$0$

Pass

Pass A to output

$0$

$1$

OR

A OR B

$1$

$0$

Increment

A$+1$

$1$

$1$

Addition

A $+$ B