if (0 < v && v < (1 << desc->exponent_size) - 1) {
/* exponent can be encoded, now check the mantissa */
v = value->desc.mantissa_size + ROUNDING_BITS - sc_get_lowest_set_bit(_mant(value));
if (0 < v && v < (1 << desc->exponent_size) - 1) {
/* exponent can be encoded, now check the mantissa */
v = value->desc.mantissa_size + ROUNDING_BITS - sc_get_lowest_set_bit(_mant(value));