const IV8 = [0x6a, 0xbb, 0x3c, 0xa5, 0x51, 0x9b, 0x05, 0x1f];
let A = useIV ? IV8[0] : 0;
let B = useIV ? IV8[1] : 0;
let C = useIV ? IV8[2] : 0;
...
A ^= m0;
B ^= m1;
C ^= (m0 + m1) & 0xFF;
for (let i = 0; i < 16; i++) {
A ^= IV8[(i + blockIndex) % IV8.length];
B ^= rol8(C, 2);
C ^= rol8(A, 3);
A = (A + C) & 0xFF;
A ^= B;
B ^= C;
C ^= A;
[A, B, C] = [B, C, A];
...