I kown how UDP algorithm working.
In this algorithm, if the last addition had overflow which was `wrapped around:
1000111100001100
1011101110110101
-----------------
10100101011000001
^
Add the overflow to the truncated result:
0100101011000001
0000000000000001
-----------------
0100101011000010
But I don't know why it must need the wraparound operation in this algorithm. Is there any advantage to wraparound operation?