公开(公告)号：DE68921663T2

公开(公告)日：1995-10-05

申请号：DE68921663

申请日：1989-04-04

Applicant: IBM

Inventor： VASSILIADIS STAMATIS ,  SCHWARZ ERIC MARK ,  FEAL BRICE JOHN ,  PUTRINO MICHAEL

IPC: G06F7/00 ,  G06F7/38 ,  G06F7/50 ,  G06F7/508 ,  G06F11/10

Abstract: An apparatus for predicting parity of a result produced by selection of the most or least significant thirty-two bits produced by a thirty-four bit adder, the parity being predicted concurrently with and independently of the result. Parity for byte Si of the selected result is derived by circuitry implementing the relationship: Pi = yP(M,n-1) V P(n,M+7) V y min P(M+8, n+7) in which Pi is the parity bit for Si, y is the positive sense of a signal indicating selection, of the most significant thirty-two result bits, y min is the complement of y and indicates selection of the least significant thirty-two result bits, P(M,n-1) is parity over the two most significant result bits in the portion of the result covering result bits m through n+7, P(m+8, n+7) is parity of the two least significant bits of the result portion, P(n, m+7) is parity over the central bits of the portion, i is an integer and 0

公开(公告)号：DE68921663D1

公开(公告)日：1995-04-20

申请号：DE68921663

申请日：1989-04-04

Applicant: IBM

Inventor： VASSILIADIS STAMATIS ,  SCHWARZ ERIC MARK ,  FEAL BRICE JOHN ,  PUTRINO MICHAEL

IPC: G06F7/00 ,  G06F7/38 ,  G06F7/50 ,  G06F7/508 ,  G06F11/10

Abstract: An apparatus for predicting parity of a result produced by selection of the most or least significant thirty-two bits produced by a thirty-four bit adder, the parity being predicted concurrently with and independently of the result. Parity for byte Si of the selected result is derived by circuitry implementing the relationship: Pi = yP(M,n-1) V P(n,M+7) V y min P(M+8, n+7) in which Pi is the parity bit for Si, y is the positive sense of a signal indicating selection, of the most significant thirty-two result bits, y min is the complement of y and indicates selection of the least significant thirty-two result bits, P(M,n-1) is parity over the two most significant result bits in the portion of the result covering result bits m through n+7, P(m+8, n+7) is parity of the two least significant bits of the result portion, P(n, m+7) is parity over the central bits of the portion, i is an integer and 0