__it_diff
case 32: diffs |= __it_diff(a, b, 64);
case 24: diffs |= __it_diff(a, b, 64);
case 16: diffs |= __it_diff(a, b, 64);
case 8: diffs |= __it_diff(a, b, 64);
case 28: diffs |= __it_diff(a, b, 64);
case 20: diffs |= __it_diff(a, b, 64);
case 12: diffs |= __it_diff(a, b, 64);
case 4: diffs |= __it_diff(a, b, 32);