XTWOT_OFFSET
k = XBIASED_EXP(x) - XTWOT_OFFSET;
if (k <= -XTWOT_OFFSET - 1)
k += XTWOT_OFFSET + 1;
k = XBIASED_EXP(x) - XTWOT_OFFSET;
if (n < -50000 || k <= -XTWOT_OFFSET - 1)
k += XTWOT_OFFSET + 1;