What control signals should be used to get the sum to output X-Y?

[hasan86bd]

Say I have a Full adder with inputs X, Y and a carry in C. How should I choose those values to make the Sum output become the difference between the X and Y input? Thanks in advance!

 

[ThisIsNotSam]

this sounds like homework

 

[dpaul]

Draw the adder table, put the 0s n 1s and calculate!

 

[BradtheRad]

The two's complement method is a computer algorithm for subtracting a binary number.

1) invert all its bits
2) add to the other number
3) add 1 to the result.