z += shiftMix(v[1]) * K1;
    x = rotateRight(z + x, 39) * K1;
    y = rotateRight(y, 33) * K1;

    // Decrease length to the nearest multiple of 64, and operate on 64-byte chunks.
    length = (length - 1) & ~63;
    do {
      x = rotateRight(x + y + v[0] + load64(bytes, offset + 16), 37) * K1;
      y = rotateRight(y + v[1] + load64(bytes, offset + 48), 42) * K1;
      x ^= w[1];