Method and apparatus for bounding alignment shifts to enable at- speed denormalized result generation in an FMAC

摘要

Method and apparatus for bounding alignment shifts to enable at- speed denormalized result generation in an FMAC (fused multiply accumulate unit; also known as a multiply-add-fused floating-point unit, or MAF/FPU). The method and apparatus force a one into an FMAC's (leading bit anticipator) at a point which is determined to yield proper alignment of a potential denormalized result (denorm result). The precise location of the forced one is determined through a comparison of the FMAC's operand exponents. If the FMAC result is indeed a denorm, the shifter will only shift up to the position of the forced one, thereby leaving the exponent at zero and producing an FMAC result with a denormalized mantissa.