I need clarfication on S-box mixing in Kuznyechik block cipher (C code)

Question

I'm still newbie to C and I need a clarfication on a code I saw on Github: https://github.com/veracrypt/VeraCrypt/blob/master/src/Crypto/kuznyechik.c#L2155

#define ILS(x1,x2,t1,t2) { \
        t1 = IT[0][(byte)(x1)][0] ^ IT[1][(byte)(x1 >> 8)][0] ^ IT[2][(byte)(x1 >> 16)][0] ^ IT[3][(byte)(x1 >> 24)][0] ^ IT[4][(byte)(x1 >> 32)][0] ^ IT[5][(byte)(x1 >> 40)][0] ^ \
            IT[6][(byte)(x1 >> 48)][0] ^ IT[7][(byte)(x1 >> 56)][0] ^ IT[8][(byte)(x2)][0] ^ IT[9][(byte)(x2 >> 8)][0] ^ IT[10][(byte)(x2 >> 16)][0] ^ IT[11][(byte)(x2 >> 24)][0] ^ \
            IT[12][(byte)(x2 >> 32)][0] ^ IT[13][(byte)(x2 >> 40)][0] ^ IT[14][(byte)(x2 >> 48)][0] ^ IT[15][(byte)(x2 >> 56)][0]; \
        t2 = IT[0][(byte)(x1)][1] ^ IT[1][(byte)(x1 >> 8)][1] ^ IT[2][(byte)(x1 >> 16)][1] ^ IT[3][(byte)(x1 >> 24)][1] ^ IT[4][(byte)(x1 >> 32)][1] ^ IT[5][(byte)(x1 >> 40)][1] ^ \
            IT[6][(byte)(x1 >> 48)][1] ^ IT[7][(byte)(x1 >> 56)][1] ^ IT[8][(byte)(x2)][1] ^ IT[9][(byte)(x2 >> 8)][1] ^ IT[10][(byte)(x2 >> 16)][1] ^ IT[11][(byte)(x2 >> 24)][1] ^ \
            IT[12][(byte)(x2 >> 32)][1] ^ IT[13][(byte)(x2 >> 40)][1] ^ IT[14][(byte)(x2 >> 48)][1] ^ IT[15][(byte)(x2 >> 56)][1]; \
    }

/\ This is the function which mixes the data block with S-boxes data in Kuznyechik cipher.

x1 and x2 contain one 64-bit word each, their nibbles are mixed with the S-boxes data and XORs are made.

But what is the order of operations ( >> and ^ )? Does the nibble is mixed with S-Boxes and XORed with the next untouched byte (no changed by mixing with S-Boxes) or is XORed with already modified next nibble?