What happens at this part in the key schedule of a Speck...?

I am trying to figure out the process behind the Speck block cipher. I understand how XOR works (Exclusive-or) when you take 2 strings of bits and you want to XOR them together.

However, in the key schedule of the cipher, there is a point where XOR takes place but I don t understand what is being XORed.

For example, in the key schedule in the link, the result of the binary addition is being XOR d with 0?

Can someone explain what this means? Thanks.

• It is round counter Sep 9, 2018 at 15:01

It's very simple: In the key schedule, the exclusive-or step after the addition is done with the round counter, and the round counter starts at $0$ rather than $1$.
So for round number $0$, the first exclusive-or is done with the value $0$. In the next round, the exclusive-or is done with the value $1$, and so forth.