Leading one anticipator and floating point addition/subtraction apparatus

摘要

A bit-discard amount anticipator anticipates a bit-discard amount within a one-bit error. A borrow propagator propagates a borrow from a least significant bit side. A selector modifies an output of the bit-discard amount anticipator to an accurate bit shift amount required at a normalization and outputs it, using information of the borrow propagator. The bit shift amount for the normalization in case where a bit discard is caused at a mantissa subtraction of a floating point calculation is accurately obtained, thus reducing a process at the normalization.