code: function qround(x, a, b, c, d) {
    x[a] += x[b];
    x[d] = rotl32(x[d] ^ x[a], 16);
  
    x[c] += x[d];
    x[b] = rotl32(x[b] ^ x[c], 12);
  
    x[a] += x[b];
    x[d] = rotl32(x[d] ^ x[a], 8);
  
    x[c] += x[d];
    x[b] = rotl32(x[b] ^ x[c], 7);
  }
docs: /*
  Helpers