Implement 3-bit carry look-ahead adder. 

sample input 

A2A1A0= 110 

B2B1B0=  101 

expected output 

S2S1S0 = 011,    

C3= 1  

Theory: Carry look ahead Adder:  Carry look-ahead adder utilizes the logic gates to look at the lower order bits of augmend and addend to see if a higher order carry is to be generated or not.  Carry look-ahead uses the two concepts of carry propagate and carry generate functions. This adder uses the following equations for ith stage: Carry propagate Pi=Ai(xor)Bi Carry generate  Gi=Ai.Bi Sum Si= Pi(xor)Ci Carry Ci+1=Gi+Pi.Ci The circuit diagram of  3-bit Carry Look-Ahead Adder is shown in the following figure: