* this is seven bits to the left of its usual location. The shifted significand
* must be normalized or smaller than this. If it's not normalized then the exponent
* `exp_z' must be zero; in that case, the result returned is a subnormal number
* this is seven bits to the left of its usual location. The shifted significand
* must be normalized or smaller than this. If it's not normalized then the exponent
* `exp_z' must be zero; in that case, the result returned is a subnormal number