| 摘要 |
PURPOSE: To speed up a calculation by dividing the calculation into two stages when the parity bit of a group forming a carry word is calculated and constituting this calculation of a first stage in which a variable depending on only a number to be added is utilized as an input variable and a high speed second stage in which a carry bit is interposed. CONSTITUTION: When a parity bit PVC is calculated by using the carry word C appearing when two binary numbers A and B are added, the am to ai , A2 , A1 and bm to bi , b2 , B1 of the group taken out from the binary numbers A and B are calculated. Namely, Pi and Gi satisfying a recurrent expression, Pi =pi .Pi-1 , Gi=gi +pi .Gi-1 (Pi =pi , Gi =gi ) are calculated. PC Y↑+Cin .X* (Cin is the lowest-order carry bit, X* is the complement of Y) is calculated.
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