CIRCUIT AND METHOD OF PREDICTING STICKY BIT VALUE

摘要

PURPOSE: To shorten delay in the multiplication operation of a processor by executing a parallel processing system for deciding a sticky bit while finding the product of two decimal parts for the processor. CONSTITUTION: A trailing zero encoder 11 receives the decimal part of a multiplicand and a trailing zero encoder 12 receives the decimal part of a multiplier, and the number of following zero contained in the decimal parts of respectively correspondent operands is decided. The trailing zero encoders 11 and 12 are inputted to a carry preservation adder 13. Further, a constant is inputted to the carry preservation adder 13. This constant is set so as to generate the execution of a carry look ahead circuit 16 when the sticky bit is '0'. Two outputs C and S of the carry preservation adder 13 are inputted to the carry look ahead circuit 16 and the sticky bit is decided there.