What is this circuit functionality?

[frank1]

Homework Statement

The question asks the circuit's functionality

FA = Full Adder

Homework Equations

The Attempt at a Solution

I got two questions:
1) To understand this circuit functionality should I write it output considering all input possibilities (32 lines)?
2) If the carry out in the last full adder is input in the first full adder, how can I establish an output? What if the last carry out affects the circuit, then changes the output?

 

[.Scott]

Your diagram only shows two adders.
Notice that the "I3" signal provides two of the adder inputs to the left adder.
So what effect will I3 have on S?

 

[frank1]

hey .Scott thanks for helping.

Your diagram only shows two adders.

It's a thumbnail, click to see the full image

Notice that the "I3" signal provides two of the adder inputs to the left adder.
So what effect will I3 have on S?

The carry-in will say who S is?

 

[.Scott]

The carry-in will say who S is?

Right.
And that provides one way of answering your second question.

Nothing that happens in the two right side adders will ever affect the left side adder.
Also, the second adder from the left is just passing signals (I3 to S1, 2nd carry to S).

 

[frank1]

Thanks for the help .Scott!